[Today we have a wonderful guest post from Marie-Claire Shanahan, continuing the conversation about what makes someone a good role model in science. This post first appeared at Shanahan's science education blog, Boundary Vision, and she has graciously agreed to let us share it here, too. Shanahan is an Associate Professor of Science Education and Science Communication at the University of Alberta where she researches social aspects of science such as how and why students decide to pursue science degrees. She teaches courses in science teaching methods, scientific language and sociology of science. Marie-Claire is also a former middle and high school science and math teacher and was thrilled last week when one of her past sixth grade students emailed to ask for advice on becoming a science teacher. She blogs regularly about science education at Boundary Visionand about her love of science and music at The Finch & Pea.] What does it mean to be a good role model? Am I a good role model? Playing around with kids at home or in the middle of a science classroom, adults often ask themselves these questions, especially when it come to girls and science. But despite having asked them many times myself, I don’t think they’re the right questions. Studying how role models influence students shows a process that is much more complicated than it first seems. In some studies, when female students interact with more female professors and peers in science, their own self-concepts in science can be improved . Others studies show that the number of female science teachers at their school seems to have no effect . Finding just the right type of role model is even more challenging. Do role models have to be female? Do they have to be of the same race as the students? There is often an assumption that even images and stories can change students’ minds about who can do science. If so, does it help to show very feminine women with interests in science like thescience cheerleaders? The answer in most of these studies is, almost predictably, yes and no. Diana Betz and Denise Sekaquaptewa’s recent study “My Fair Physicist: Feminine Math and Science role models demotivate young girls” seems to muddy the waters even further, suggesting that overly feminine role models might actually have a negative effect on students.  The study caught my eye when PhD studentSara Callori wrote about it and shared that it made her worry about her own efforts to be a good role model. Betz and Sekaquaptewa worked with two groups of middle school girls. With the first group (144 girls, mostly 11 and 12 years old) they first asked the girls for their three favourite school subjects and categorized any who said science or math as STEM-identified (STEM: Science, Technology, Engineering and Math). All of the girls then read articles about three role models. Some were science/math role models and some were general role models (i.e., described as generally successful students). The researchers mixed things even further so that some of the role models were purposefully feminine (e.g., shown wearing pink and saying they were interested in fashion magazines) and others were supposedly neutral (e.g., shown wearing dark colours and glasses and enjoying reading).* There were feminine and neutral examples for both STEM and non-STEM role models. After the girls read the three articles, the researchers asked them about their future plans to study math and their current perceptions of their abilities and interest in math.** For the most part, the results were as expected. The STEM-identified girls showed more interest in studying math in the future (not really a surprise since they’d already said math and science were their favourite subjects) and the role models didn’t seem to have any effect. Their minds were, for the most part, already made up. What about the non-STEM identified girls, did the role models help them? It’s hard to tell exactly because the researchers didn’t measure the girls’ desire to study math before reading about the role models. It seems though that reading about feminine science role models took away from their desire to study math both in the present and the future. Those who were non-STEM identified and read about feminine STEM role models rated their interest significantly lower than other non-STEM identified girls who read about neutral STEM role models and about non-STEM role models. A little bit surprising was the additional finding that the feminine role models also seemed to lower STEM-identified girls current interest in math (though not their future interest). The authors argue that the issue is unattainability. Other studies have shown that role models can sometimes be intimidating. They can actually turn students off if they seem too successful, such that their career or life paths seem out of reach, or if students can write them off as being much more talented or lucky than themselves. Betz and Sekaquaptewa suggest that the femininity of the role models made them seem doubly successful and therefore even more out of the students’ reach.
The second part of the study was designed to answer this question but is much weaker in design so it’s difficult to say what it adds to the discussion. They used a similar design but with only the STEM role models, feminine and non-feminine (and only 42 students, 20% of whom didn’t receive part of the questionnaire due to an error). The only difference was instead of asking about students interest in studying math they tried to look at the combination of femininity and math success by asking two questions:
“How likely do you think it is that you could be both as successful in math/science AND as feminine or girly as these students by the end of high school?” (p. 5)
“Do being good at math and being girly go together?” (p. 5)
Honestly, it’s at this point that the study loses me. The first question has serious validity issues (and nowhere in the study is the validity of the outcome measures established). First, there are different ways to interpret the question and for students to decide on a rating. A low rating could mean a student doesn’t think they’ll succeed in science even if they really want to. A low rating could also mean that a student has no interest in femininity and rejects the very idea of being successful at both. These are very different things and make the results almost impossible to interpret.
Second these “successes” are likely different in kind. Succeeding in academics is time dependent and it makes sense to ask young students if they aspire to be successful in science. Feminine identity is less future oriented and more likely to be seen as a trait rather a skill that is developed. It probably doesn’t make sense to ask students if they aspire to be more feminine, especially when femininity has been defined as liking fashion magazines and wearing pink.
Question: Dear student, do you aspire to grow up to wear more pink?
Answer (regardless of femininity): Um, that’s a weird question.
With these questions, they found that non-STEM identified girls rated themselves as unlikely to match the dual success of the feminine STEM role models. Because of the problems with the items though, it’s difficult to say what that means. The authors do raise an interesting question about unattainability, though, and I hope they’ll continue to look for ways to explore it further.
So, should graduate students like Sara Callori be worried? Like lots of researchers who care deeply about science, Sara expressed a commendable and strong desire to make a contribution to inspiring young women in physics (a field that continues to have a serious gender imbalance). She writes about her desire to encourage young students and be a good role model:
When I made the decision to go into graduate school for physics, however, my outlook changed. I wanted to be someone who bucked the stereotype: a fashionable, fun, young woman who also is a successful physicist. I thought that if I didn’t look like the stereotypical physicist, I could be someone that was a role model to younger students by demonstrating an alternative to the stereotype of who can be a scientist. …This study also unsettled me on a personal level. I’ve long desired to be a role model to younger students. I enjoy sharing the excitement of physics, especially with those who might be turned away from the subject because of stereotypes or negative perceptions. I always thought that by being outgoing, fun, and yes, feminine would enable me to reach students who see physics as the domain of old white men. These results have me questioning myself, which can only hurt my outreach efforts by making me more self conscious about them. They make me wonder if I have to be disingenuous about who I am in order to avoid being seen as “too feminine” for physics.
To everyone who has felt this way, my strong answer is: NO, please don’t let this dissuade you from outreach efforts. Despite results like this, when studies look at the impact of role models in comparison to other influences, relationships always win over symbols. The role models that make a difference are not the people that kids read about in magazines or that visit their classes for a short period of time. The role models, really mentors, that matter are people in students’ lives: teachers, parents, peers, neighbours, camp leaders, and class volunteers. And for the most part it doesn’t depend on their gender or even their educational success. What matters is how they interact with and support the students. Good role models are there for students, they believe in their abilities and help them explore their own interests.
My advice? Don’t worry about how feminine or masculine you are or if you have the right characteristics to be a role model, just get out there and get to know the kids you want to encourage. Think about what you can do to build their self-confidence in science or to help them find a topic they are passionate about. When it comes to making the most of the interactions you have with science students, there are a few tips for success (and none of them hinge on wearing or not wearing pink):
§ Be supportive and encouraging of students’ interest in science. Take their ideas and aspirations seriously and let them know that you believe in them. This turns out to be by far one of the most powerfulinfluences in people pursuing science. If you do one thing in your interactions with students, make it this.
§Share with students why you love doing science. What are the benefits of being a scientist such as contributing to improving people’s lives or in solving difficult problems? Students often desire careers that meet these characteristics of personal satisfaction but don’t always realize that being a scientist can be like that.
§Don’t hide the fact that there are gender differences in participation in some areas of science (especially physics and engineering). Talk honestly with students about it, being sure to emphasize that differences in ability are NOT the reason for the discrepancies. Talk, for example, about evidence that girls are not given as many opportunities to explore and play with mechanical objects and ask them for their ideas about why some people choose these sciences and others don’t. There are so many ways to encourage and support students in science, don’t waste time worrying about being the perfect role model. If you’re genuinely interested in taking time to connect with students, you are already the right type.
* There are of course immediate questions about how well supported these are as feminine characteristics but I’m willing to allow the researchers that they could probably only choose a few characteristics and had to try to find things that would seem immediately feminine to 11-12 year olds. I still think it’s a shallow treatment of femininity, one that disregards differences in cultural and class definitions of femininity. (And I may or may not still be trying to sort out my feelings about being their gender neutral stereotype, says she wearing grey with large frame glasses and a stack of books beside her).
**The researchers unfortunately did not distinguish between science and math, using them interchangeably despite large differences in gender representation and connections to femininity between biological sciences, physical sciences, math and various branches of engineering.
 Stout, J. G., Dasgupta, N., Hunsinger, M., & McManus, M. A. (2011). STEMing the tide: Using ingroup experts to inoculate women’s self-concept in science, technology, engineering, and mathematics (STEM).Journal of Personality and Social Psychology, 100, 255-270.
 Gilmartin, S., Denson, N., Li, E., Bryant, A., & Aschbacher, P. (2007). Gender ratios in high school science departments: The effect of percent female faculty on multiple dimensions of students’ science identities.Journal of Research in Science Teaching, 44, 980–1009.
 Betz, D., & Sekaquaptewa, D. (2012). My Fair Physicist? Feminine Math and Science Role Models Demotivate Young Girls Social Psychological and Personality Science DOI: 10.1177/1948550612440735
Buck, G. A., Leslie-Pelecky, D., & Kirby, S. K. (2002). Bringing female scientists into the elementary classroom: Confronting the strength of elementary students’ stereotypical images of scientists. Journal of Elementary Science Education, 14(2), 1-9.
Buck, G. A., Plano Clark, V. L., Leslie-Pelecky, D., Lu, Y., & Cerda-Lizarraga, P. (2008). Examining the cognitive processes used by adolescent girls and women scientists in identifying science role models: A feminist approach. Science Education, 92, 2–20.
Cleaves, A. (2005). The formation of science choices in secondary school.International Journal of Science Education, 27, 471–486.
Ratelle, C.F., Larose, S., Guay, F., & Senecal, C. (2005). Perceptions of parental involvement and support as predictors of college students’ persistence in a science curriculum. Journal of Family Psychology, 19, 286–293.
Simpkins, S. D., Davis-Kean, P. E., & Eccles, J. S. (2006). Math and science motivation: A longitudinal examination of the links between choices and beliefs. Developmental Psychology, 42, 70–83.
Stout, J. G., Dasgupta, N., Hunsinger, M., & McManus, M. (2011). STEMing the tide: Using ingroup experts to inoculate women’s self-concept and professional goals in science, technology, engineering, and mathematics (STEM). Journal of Personality and Social Psychology, 100,255–270.
When I take a look around my office I see a lot of men, mostly older White men. There are also women, mostly administrative assistants, accountants, and marketing personnel, but few like me. I am an engineer, and I am young, female, Ivy League educated, and Hispanic. I took the same science and mathematics classes all my male peers took. I was given the same tests, the same homework assignments, and the same projects. Yet, every day I have to battle stereotypes of what some think women should be.
Courtesy of Indiana University.
Engineering, and most science fields, have long been male-dominated professions. Yet, in spite of traditional gender roles pigeonholing women to domestic duties, women haven’t necessarily settled into domesticity without first making many great advances in the science fields. We cannot forget Merit-Ptah, an ancient Egyptian physician, and also the first woman to be known by name in the history of the field of Medicine. Or the ancient Greek philosopher Hypatia, also the first historically noted woman in Mathematics. These women were not given positions in Science to fill a status quo, they earned it, just like women today.
Stereotypes are part of my daily life. In high school I was discouraged by a school teacher to apply to Engineering school, because she claimed it was “harder than I was imagining it to be.” She told me that I wanted to pursue a degree in Engineering because of the money I would earn, but it was clear to her that I did not have a passion for it. Never mind that I outperformed all my classmates, including all my male peers, and that I was about to graduate at the top of my class. As a professional adult, I still face these misconceptions about women in science fields. I get my bosses’ mail delivered to me every day because the delivery man, after four years, still thinks that I am a secretary. I politely remind him every day that I am in fact, also an engineer, like my boss, but it seems to fall on deaf ears. So I find myself not only doing my work, but also delivering mail. A week ago I was asked by a new employee which department I belonged in, and the conversation went like this:
Me: “Hi, are you new to our office?”
New Employee: “Yes, I work in the Marketing department. Do you work with Corporate?”
Me: “No, I work in the Transportation and Infrastructure department.”
New Employee: “Are you an administrative assistant?”
Me: “No, an Engineer.”
New Employee: “Oh, you’re an Accountant.”
Me: “Noooo, an Engineer, a Civil Engineer!”
New Employee: “Oh, wow! I would have never guessed…you don’t look like one.”
While I admit to becoming irritated, it was more disconcerting that this co-worker was also a young woman like myself. She reacted in a way that was natural and all too common, because there really aren’t enough women being positively represented in the fields of Science, Technology, Engineering, and Mathematics (STEM). I quite enjoy shaking up perceived ideas of what society assumes I should be, as a woman, a woman of color, and a woman in a male-dominated field, but when will all this shock and awe over women in science fields end? Nonetheless, I love the work I do and the feeling of accomplishment I get when I finish a project. And contrary to 18th century views of the female brain, we have shown that when given the same curriculum as men, we can equally excel.
According to a research study done by the University of Washington, the main culprit for girls not becoming enthusiastic about careers in mathematics and science is gender-stereotyping. The study speaks of the widespread cultural belief in the “girls don’t do math” stereotype. In the study, 247 school-age children (126 girls and 121 boys) were asked to sort four kinds of words: boy names, girl names, math words and reading words, into categories, with the use of an adapted keyboard on a laptop. The lead author of the study, Dario Cvencek, concluded that: “Not only do girls identify the stereotype that math is for boys, but they apply that to themselves. That’s the concerning part. Girls are translating that to mean, ‘Math is not for me.’”
While the study found that both genders equate mathematics with boys, it is unclear why this stereotype is so pronounced at such a young age, though there seems to be a connection with the way in which we speak to young children about mathematics. Dario Cvencek explains: “When a girl does poorly on a math test, often she’s told, ‘That’s fine. You did your best.’ When a boy does poorly, he is more likely to be told, ‘You can do better. Try harder next time.’”
Stereotypes are hurtful, and I believe that stereotype threat, the notion that we experience anxiety in a situation where we have the potential to confirm a negative stereotype, is all too real. We cannot expect young girls to be interested in pursuing careers in science, technology, engineering, and mathematics, if we continue to associate them with one gender. Stereotyping career choices is not in our best interest as we cannot achieve success if we believe that half of our population is not capable of contributing to the betterment of our society. I challenge every educator and parent to reevaluate the way they educate their children. Think about the toys we give them. Building blocks and other shape-sorting toys are equally entertaining for girls as they are for boys, and they help develop cognitive skills, something Barbie and Easy-Bake Ovens will never achieve. Teaching is powerful, and encouraging children to challenge themselves should not depend on the child’s gender.
I am passionate about increasing the number of women represented in STEM fields, not merely because I believe we should be equally represented in all career fields, but because I know we can positively contribute to the advancement of our society. Having both sexes equally represented opens the door for a more diverse range of ideas, which in turn can result in a more robust range of services and products. Additionally, having more women in STEM fields ensures that women’s health and well-being become common practice, and not women’s issues.
Careers in STEM fields require high-level skills and earn higher wages, they are also always in high demand, and experts predicts an even stronger demand for professionals in STEM fields in the future. Our economy is in crisis and 60% of women are the breadwinners or co-breadwinners in their families. If we continue to believe that these high paying careers are only for men, we are not cashing in on the earning power of women. Ultimately, it is not about filling a status quo, it is about using our population, men and women, to the best of their abilities.
Patricia Valoy is a Civil Engineer and an Assistant Project Manager at STV, an architectural, engineering, planning, environmental and construction management firm based in New York City. She is a graduate of the Columbia University School of Engineering in Applied Science, where she majored in Civil Engineering with a concentration in Construction Management. Patricia also is a co-host of a weekly radio show called, “Let Your Voice Be Heard.” The show’s mission is to spread awareness of social and political issues. In addition, she writes a blog about feminist issues and mentors high school and college students interested in pursuing careers in STEM fields. You can follow Patricia on Twitter at @besito86 and read her blog at www.patriciavaloy.blogspot.com.
Deborah is the first Mexican woman to graduate with a physics PhD from Stanford University. She is a physicist, author, and media personality whose initiatives to popularize science have impacted thousands of people around the world. Her passion is to popularize science and motivate young minds to think analytically about the world. This has led her to pioneer learning initiatives in schools and universities in Mexico, Africa, the US and Israel. She is a frequent public speaker and has been recognized by numerous media outlets such as Oprah, CNN, WSJ, TED, DLD, WIRED, Martha Stewart, City of Ideas, Dr. Oz Show, Celebrity Scientist and others. She regularly appears as a science expert on different international TV networks; currently she is the TV host of National Geographic’s “Humanly Impossible” show. And she will appear on the Discovery Channel’s upcoming show ‘You’ve Been Warned.’ You can find Deborah on Twitter, or on her blog, Science With Debbie. You can also find Deborah telling her story for The Story Collider.
DXS: First, can you give me a quick overview of what your scientific background is and your current connection to science?
I grew up in Mexico City in a fairly conservative community, and as a child, I was discouraged from doing and studying science. My parents, family, and peers would all ask, “oh, why don’t you study a more feminine career?” Although I was pretty good in school, I wasn’t exactly a math wizard. I used to say that I loved philosophy and physics – because philosophy was a deep discipline of asking questions about the world. And physics studied the world itself.
It was clear when I was born that my personality waswas quite different to the one of my mom. When I was growing up, my mom was scared because she didn’t know what to do with this little girl that was smart and always asking questions. She is not a naturally curious person, so she kept trying to tame down my curiosity and kept telling me not to tell boys that I was interested in math and science because I would never find a husband. According to her, the life goal for a girl was to find a husband, have kids, and that’s it. Women didn’t have to have a career. (Not that there is anything wrong with not having a career.) My high school teachers and counselors were not so different and encouraged me to go into philosophy or literature, not into math or physics. And my friends in school told me I literally had to be an out of the world genius to be able to study physics.
Given the circumstances, I started studying philosophy in Mexico. There were some classes with logic, and some with a little bit more math, and those were the ones I just devoured! And, at the same time – secretly – I was reading the biographies of scientists. For some bizarre reason, I was hugely attracted to their life stories. I didn’t have any family members, or anyone else for that matter, that had pursued a career in science, so I didn’t have a mentor or a role model. I felt an extreme kinship with Tycho Brahe, who in the late 1500’s was locked in a tower, doing all of these calculations for years, hated by everyone in the town. Go figure! I felt some kinship with these scientists. But I didn’t have the courage nor the means to switch majors. I did confess that I wanted to study another area (physics), but in Mexico one cannot study two majors. So, I studied philosophy for two years.
In the middle of it, I felt way too curious about science and I decided to apply to schools in the US. It was hard at the time because college in Mexico was a lot cheaper than in the states. At the private school where I was attending, my tuition was about $5,000 per year. If I were to come to the US, I would be looking at costs exceeding $35,000 per year. I couldn’t really ask my dad to help me with that price tag so I started to apply everywhere and anywhere that had scholarship opportunities.
I ended up getting a letter from Brandeis
University saying that they would let me take this advanced placement test and write an essay, which, if I did well, would give me a full scholarship. I received a full Wien Scholarship and was to continue studying philosophy in the US. This was probably the nicest thing that has ever happened to me because it opened the path of opportunity.
Brandeis transformed me as a person – I saw females doing science! But, the bravado moment that changed my life was a very general course called Astronomy 101. The teaching assistant, Roopesh, was a very sweet man from India and he saw that my eyes would just light up when I was in that class – I was much more curious than the random student that was just taking it to fulfill some requirement.
At the end of that year, Roopesh and I
were walking around Harvard Square and stopped to sit under a tree. I started to tell him, with tears in my eyes, that I just don’t want to die without trying. What I meant by that is I don’t want to die without trying to do physics. Everyone’s questioning of my decision made me question my actual ability. Everyone telling me ‘no’ hampered my development. I mean, I was good at math, but I definitely didn’t have the same background as all the kids coming in with advanced math and physics courses.
I told Roopesh that I don’t even remember how to solve the equation (a+b)2 – even my algebra was rusty! But, he believed in me and went back to his professor and told him my story. This professor decided to meet with me and ends up telling me about someone who had done this sort of thing in the past. His name was Ed Witten and he went on to become the father of string theory.
He said “Witten had switched from history to physics, and I will let you try too.” With that, he handed me a book on vector calculus called ‘Div, Grad and Curl’ and told me that If I could master it in three months by the end of the summer, they would let me switch my major to physics and also let me bypass the first two years of course work. This would allow me to graduate by the time my scholarship ran out.
I have never in my life experienced the level of scientific passion condensed into such a short amount of time and I am jealous of the person I was that summer. I had so much perseverance and focus. I don’t think I can ever reproduce that intensity again. From the moment I woke up to the moment I went to sleep, and even in my dreams, I only thought about physics. Roopesh, who became my mentor for the summer, taught me.
I always wanted to pay Roopesh for his tutoring, but he would never accept any money. He told me that when he was growing up in the mountains of Darjeeling in India, there was this old man who would climb up to his home and teach him and his sisters English, the musical instrument Tabla, and math. Roopesh’s father always wanted to pay the old man for his tutoring, but the man always declined. The man said that the only way he could ever pay him back was if Roopesh did the same thing with someone else in the world. And by mentoring me, Roopesh fulfilled his payment to the old man.
Out of that, that became a seed for my physics journey and purpose. It is now my life’s mission to do the same for other people in the world – especially women – who feel attracted to science but feel trapped. They for some reason, whether it is social, financial, etc., just can’t find the way toward science. That is the motivation that dictates my actions.
I was able to pull it off and graduated Brandeis Summa Cum Laude with highest honors in physics and philosophy. I went back to Mexico afterwards to figure out what to do next and to spend some time with my family. At the same time, I did a master’s degree in physics at the largest university in Mexico UNAM. My curiosity for physics didn’t diminish and in 1998, I randomly applied to two physics PhD programs in the US. I applied very, very late, but, fortunately, I won a merit-based full scholarship from the Mexican government who provided me with funding, which made it easier for me.
Because I loved biophysics, I did a search on who was doing this line of research. I came across Steven Chu, who is currently the secretary of energy. At the time I was applying, he was at Stanford and was one of the first to manipulate a single strand of DNA with his ‘optical tweezers.’ To me, his story was fascinating! Without really knowing who he was other than what I found on the web, I wrote him an email asking him if I could work in his lab. Had I known who he was – that he had just won the Nobel prize in 1997 – I would have been too intimidated.
I was admitted to Stanford and was invited to work with Dr. Chu, but after two years I decided to switch labs. As expected, it was a very challenging environment and having only studied two years of physics at Brandeis, I wasn’t as prepared as most of the other students. I struggled for the first two years. Everyone worked so extremely hard at Stanford and there I was, struggling to be the best, but, in the beginning, I couldn’t even be average.
Fast forward four years. I had worked my butt off and ended up becoming the first Mexican woman to graduate with a PhD in physics from Stanford. It was the best day of my life – I kept thinking that I was so blessed to have my parents live to see this! It was so moving, I was crying so much and I couldn’t believe what had happened. My friends had flown in from all over the world to be with me. It was amazing.
When people hear what I do, they – especially teenage girls – feel intimidated. But, when they hear the whole story, their tune changes. I tell them that I know what it is like to not understand something. I was not the kind of person where comprehension of my science came naturally. But I did it. And if I can do it, anyone can do it! My story can be inspirational to someone who comes from a background completely lacking in science because they, like me, can reach their goal.
DXS: What ways do you express yourself creatively that may not have a single thing to do with science?
I was always a very curious girl growing up. I had a lot of interests, one of which being theatre. I wanted to be an actress when I was young, but my father didn’t let me pursue that as a career, which was probably a good idea. But, during high school, I went to an after school drama program. I wrote my own plays – three of them – and performed one of them. I was in heaven when I was on stage.
In NY, I have tried to do a little bit of that. Of course, I’ve never done any big roles, but I will be an extra in a film, or if there is a small production being made in Spanish, I will play a part. It doesn’t matter how big the role is – I just love doing something creative and getting into a character.
DXS: What types of productions and/or films have you done?
I don’t think I would come up in the credits as an extra, but I did a movie with Simon Pegg, Kirsten Dunst and Megan Fox in the movie “How to lose Friends and Alienate People.” It was a very, very fun film! In theatre, Jean Genet, who is a French playwright, has a play called The Maids, and I was the madame.
DXS: Do you find that your scientific background informs your creativity, even though what you do may not specifically be scientific?
Debbie talking to the TEDYouth audience about waves.
I have a concept that I call “physics glasses.” And what I mean by that is, for me, physics is not a subject that you just teach in a complex way in a classroom. Rather, physics is something that is related to everyday life. From the moment you wake up, you can just put on your physics glasses. It is a mode of thinking – it is a way where although reality can be very rich and diverse, physics goes very deep and it abstracts commonalities, general principles that apply to many things. To give you an example, I asked the kids in the audience of my TEDYouth talk, “what do the sun, the ocean, and a symphony orchestra have in common?” When just looking at them on the surface, there isn’t much in common. I mean, they are all beautiful things but they are not obviously related. But, to a physicist, they are all waves. You have sound waves, light waves, and water waves and you can interchange many of the concepts in physics to explain all three.
Where most of us see the world with our eyes through light waves, other might see the world differently. Take, for example, my friend Juan, who is blind. He “sees” the world with sound waves – he senses sound as it bounces off the objects around him. Through this, he can bike, play basketball, and do a load of activities using sound as a guide. This is one of my favorite analogies because, really, physics “infects” the way I see the world.
Deborah the Physicist model
To give you a more specific example in the creativity realm, when I got to NY, I felt really un-feminine. When I was studying physics, I felt that if I was even slightly feminine, I wouldn’t be respected. It didn’t help that some of the other women in the physics program at Stanford were more of a “guys girl,” always wearing a baseball cap and t-shirts. Now, since I am Latin, I first showed up wearing a skirt to class, but I quickly learned to dress down. Looking feminine would assure that no one would talk to me in class.
So, when I got to NY, I had an explosion. I wanted to know what it was like to express myself as a woman and my friend suggested that I do some modeling. So I did. It was a brief, lasting about a year. But during that time, my friend, who was a designer from Mexico, asked me to work with her and I wrote and did some videos about the physics of fashion, which also included the physics of high heels video.
Some people could consider fashion to be superficial, but not me. I love fashion and color. But, other scientists generally looked down upon you for liking this sort of thing. This fueled my desire to prove to everyone that there actually is science everywhere, including fashion, and that they shouldn’t be snobs about it. There is complex science in how different materials work, how they interact with the environment and you can prove to the women, like my mother and friends back home who think that science has nothing to do with their everyday lives, that it has EVERYTHING to do with it. So I talked about a Newtonian theory for color – how to pick the right color for you based on how much light the color would reflect on that day, etc.
DXS: Like a more sophisticated version of colors based on your “season?”
I also did pieces on the materials, including some of the newest engineering accomplishments with fabric. For example, I hooked up with a woman and helped her to design a fashionable and very scientific coat. It ended up costing $11,000, but it was made up of nano fibers and it had a patch in it that could detect the temperature and the probability of rain. Based on this probability, it could change permeability of the fabric. It was a very light coat that was comfortable in nice weather, but when it would rain, it would become impermeable to water once it detected a high probability of rain, transforming into a raincoat.
DXS: That’s incredible! I wish it wasn’t $11,000!
DB: Yeah, that’s usually the problems with these technologies. They are often so novel, but one day I’m sure we can figure out how to make things like this scalable.
Science is very much what guides my thinking when I am being creative and I wish I had more time to do creative things while being influenced by a scientific mindset.
DXS: It is so cool that physics has such an incredible overlap with everyday living. Like, when we take a shower, I want to know “how is the water getting pumped from the ground or through pipes and make its way out of the showerhead?” But, as a biochemist, I often find it hard to relate everyday things to biochemistry, but I would like to!
DB: Its funny that you say that. When I try to teach girls that the worst thing they can do is memorize. Critical thinking is so important and they shouldn’t take anything at face value, and they should even question teachers and authoritative figures in their lives. Always ask: what goes into making this? Why is this here? Why is it this way and not another? Constantly ask questions. That s the gift that physics will give you.
DXS: Have you encountered situations in which your expression of yourself outside the bounds of science has led to people viewing you differently–either more positively or more negatively?
Without saying I am a scientist, I can tell you that people have come up to me and told me that before they even hear me speak, they think I am dumb. They are usually surprised that I am smart! I think it is because I am bubbly and friendly and that often makes an impression as being unintelligent. For them it seems that if a woman is intelligent, she is very cold and distant and serious.
I’ve met a lot of physicists, and yes, some of them do tend to be that way, often as a reaction to how others treat them. Or, people would say to me that, because I am Latin, my cultural identity comes across as being warm and the last thing they’d expect me to be into was something as cold as physics. So yeah, I have definitely been judged so many times!
It even happens in my current job on Wall Street, especially with my male peers. When there are off site client meetings, I’m often accompanied by my male sales colleague. Sales people are generally required to know less about the complexities behind our risk models compared to someone on a more research-oriented role, like me and he will bring me along to these sales meetings in case the potential client has more sophisticated questions that go beyond what he can comfortably answer. Many times upon meeting the clients for the first time they think that I am the sales person, there to be the smiling face to sell them something, and that he is the risk modeler. They always direct their mathematical questions to him.
It came to a point where I became so annoyed that I decided to stop caring. Now, my sales colleague goes out for drinks with the clients and I know that I am going to be invisible. So I don’t go anymore. I know that I am always going to struggle to get the full intellectual respect in that industry – it will always be a challenge.
DXS: Have you found that your non-science expression of creativity/activity/etc. has in any way informed your understanding of science or how you may talk about it or present it to others?
Yes, absolutely. For example in Mexico, unlike the US, you absolutely have to do an honors thesis project as an undergradin science. Because I had already studied philosophy for four years, I wanted to do a thesis project in philosophy. But I also wanted to do one in physics. I recall that back in 1997, when you presented a dissertation in front of the physics community, if you had any power point, forget it. You would be immediately be called dumb or not a good physicist. Because, who takes the time to do something fancy! If you had any color in your presentation, forget it!
So, literally, the smartest students in physics were people who didn’t really communicate that well, or didn’t really speak English that well, or just didn’t really make an effort. Their slides were on those overhead projector things with those rolls of plastic sheets, and most of their talks were so confusing and couldn’t be interpreted! But they were respected! It was just assumed that if the formula looked complex, they were probably right.
So what I did was completely different. I infused my talk with my spiciness and color. I did an artwork of liquid crystals, which was my research at Brandeis. Liquid crystals are little cigar-shaped molecules that actually make up the screen of your laptop. If you pass an electric field through them, they all orient themselves and that is how we can use them for displays in our laptops and TVs.
I colored these cigar-shaped molecules with purples and reds and greens, and I tried to explain it at the most basic level. This is because of one my philosophy professors in Mexico, who told me that if you cannot explain what you do to your grandmother or 6 year old niece, you don’t understand what you are doing – I loved it!
And I said to myself that I shouldn’t care what they think. I pretty much expected to not gain a lot of respect from the physics department, but it had the opposite effect! I actually had one of the professors from that department come up to me and tell me that he had never really understood what a liquid crystal looked like or what it really was! He said that “finally I understand [liquid crystals] because of your drawing. Thank you!” It was incredible!
To see the effect on people and from then on, I bounced up in down, I made jokes, I put in creativity. It doesn’t always have a great effect on very serious audiences, but the younger generation is definitely appreciative. When it keeps going well, you gain confidence. And, for me, I even started wearing high heels to the next talk. When someone commented about my attire, I would counter, hey I have a PhD!
DXS: How comfortable are you expressing your femininity and in what ways? How does this expression influence people’s perception of you in, say, a scientifically oriented context?
This question is deep and a little bit of a struggle at the moment. This is because I still have that fear – when I arrived in NY, I did that short stint in modeling and I expressed myself and I would dress very creatively – just like my other girlfriends who were not scientists. But I did feel a little bit of a backlash. By that I mean that I would post a photo of myself on Facebook or something like that. They were pretty pictures, not at all seductive or provocative, and my high school mates, usually male, would write me saying: “I always knew you as a serious person and you have achieved so many things – I am just telling you for your own good that this can really damage your image.” That made me reply with “so you’re telling me that being smart is actually kind of a bummer?” That actually means that I have to dress very differently from what other women wear for the rest of my life?
I remember feeling very upset about all of that. I think that not being taken seriously is still a little bit of a fear of and I think my website has damaged my serious image a little bit. As a scientist, I was very secluded from the outside world. I didn’t have a lot of friends when I moved here, but I did know an amazing and powerful woman who happened to be the CEO of Blip TV. She was insisting that I do videos! So she invited me to her place and showed me how to do video. Being the quick woman that she was, she asked me to make up a name for myself on the spot. When I didn’t answer, she instantly coined “The Science Babe” for me. I was like, sure, what a cool idea!
It was kind of a cute name, but because English is not my first language, I don’t always understand some of the cultural connotations associated with some English words. A few months later, I started to get a few emails from mothers who were upset that I was using my looks. They would say things like “Are you saying that women have to be in the kitchen or wear short skirts to be scientists?” I would answer that no, that was not it at all. I would further explain that I was trying to change the definition of “babe.” If you are smart, if you are empowered, you will be a babe no matter how you look. I am trying to shift what people think of when they think “scientist.”
I don’t feel quite successful with The Science Babe. It seems like there are quite a few people, especially some from the older generation, who say that they’d love to introduce me to fancy science organizations but are worried that the name “the science babe” will make it difficult. Also, I had the BBC wanted to talk to me about doing a TV show in NY, and then they said but there’s so much bad stuff out there about you! And I was like, what do you mean? They answered “All these things with the “science babe” brand…”
It doesn’t happen all the time, but some people are really critical about the science babe theme, citing that its way too feminine. Other female scientists that haven’t gone that route have perhaps discounted my seriousness about science. They assume that what I am doing is not really that important because I do focus on the science everyday life, which is simpler, and it is too much color and too much vivaciousness for our field. I feel like my femininity has decreased over the last few years because I’ve been too nervous about not being taken seriously. It s almost like the balance tipped the other way. I feel like perhaps I’ve feminized things to a fault and now I want to appear more serious. So, I am changing my website to “Science With Debbie” because I really felt the backlash.
It is a struggle to find the balance between being able to express my femininity and presenting myself in a way that people will take me seriously. In a way, I wish I had a little more courage to not care that much about what people have to say about the science babe but, unfortunately, agents have told me that if I don’t go to the “dumbed down version of femininity” I would get better speaking engagements. Being feminine has literally affected my career, and it’s because of other people’s perceptions. I’m never going to be bland, but I will try to change things so I am more serious
DXS: Do you think that the combination of your non-science creativity and scientific-related activity shifts people’s perspectives or ideas about what a scientist or science communicator is? If you’re aware of such an influence, in what way, if any, do you use it to (for example) reach a different corner of your audience or present science in a different sort of way?
The fact that I am approachable and pretty down to earth has allowed me to reach corners of society that more distant and fancy scientists would never even consider. For instance, I am going to a small university to give a talk. Some of my friends ask why I even bother, especially considering that this insitution is not the most renowned university. But, I feel the opposite – it is these corners that need the influence the most! Similarly, when I go to Hispanic high schools, many of the mothers have never seen a scientist. And there I am, a scientist from Mexico, speaking to them and their kids. It is that powerful combination of being a smart and warm female that can be shocking, which is cool.
In line with this, there was an experiment where women were asked to draw a female scientist. Most drew a plain, relatively unattractive woman. Immediately when you break that mold, it has an incredible effect. People say, “Hey! She kind of looks like me and she dresses like me. Maybe I can do science too!” Some girls are afraid that by being smart, boys won’t talk to them. My femininity allows me to be a voice in a field that has tended to isolate themselves from the public, which is bad. Some of my colleagues have become a little snobbish. The fact that I have serious credentials (PhD and 2 postdocs) shows that I had to work like crazy – looks and personality can only go so far. It s hard work that gets you there! Serious science communication has a lot of math and problem solving in order to explain things accurately to the public. So I still feel like I am doing science!
Vocal fry: I (Emily) am a biologist. This phrase makes me think of tiny, loudmouthed fish. But it’s reallyabout a vocal tic. Do you do this when you speak? It’s all the rage among young XXers these days.
The four basic categories of molecules for building life are carbohydrates, lipids, proteins, and nucleic acids.
Carbohydrates serve many purposes, from energy to structure to chemical communication, as monomers or polymers.
Lipids, which are hydrophobic, also have different purposes, including energy storage, structure, and signaling.
Proteins, made of amino acids in up to four structural levels, are involved in just about every process of life.
The nucleic acids DNA and RNA consist of four nucleotide building blocks, and each has different purposes.
The longer version
Life is so diverse and unwieldy, it may surprise you to learn that we can break it down into four basic categories of molecules. Possibly even more implausible is the fact that two of these categories of large molecules themselves break down into a surprisingly small number of building blocks. The proteins that make up all of the living things on this planet and ensure their appropriate structure and smooth function consist of only 20 different kinds of building blocks. Nucleic acids, specifically DNA, are even more basic: only four different kinds of molecules provide the materials to build the countless different genetic codes that translate into all the different walking, swimming, crawling, oozing, and/or photosynthesizing organisms that populate the third rock from the Sun.
Big Molecules with Small Building Blocks
The functional groups, assembled into building blocks on backbones of carbon atoms, can be bonded together to yield large molecules that we classify into four basic categories. These molecules, in many different permutations, are the basis for the diversity that we see among living things. They can consist of thousands of atoms, but only a handful of different kinds of atoms form them. It’s like building apartment buildings using a small selection of different materials: bricks, mortar, iron, glass, and wood. Arranged in different ways, these few materials can yield a huge variety of structures.
We encountered functional groups and the SPHONC in Chapter 3. These components form the four categories of molecules of life. These Big Four biological molecules are carbohydrates, lipids, proteins, and nucleic acids. They can have many roles, from giving an organism structure to being involved in one of the millions of processes of living. Let’s meet each category individually and discover the basic roles of each in the structure and function of life.
You have met carbohydrates before, whether you know it or not. We refer to them casually as “sugars,” molecules made of carbon, hydrogen, and oxygen. A sugar molecule has a carbon backbone, usually five or six carbons in the ones we’ll discuss here, but it can be as few as three. Sugar molecules can link together in pairs or in chains or branching “trees,” either for structure or energy storage.
When you look on a nutrition label, you’ll see reference to “sugars.” That term includes carbohydrates that provide energy, which we get from breaking the chemical bonds in a sugar called glucose. The “sugars” on a nutrition label also include those that give structure to a plant, which we call fiber. Both are important nutrients for people.
Sugars serve many purposes. They give crunch to the cell walls of a plant or the exoskeleton of a beetle and chemical energy to the marathon runner. When attached to other molecules, like proteins or fats, they aid in communication between cells. But before we get any further into their uses, let’s talk structure.
The sugars we encounter most in basic biology have their five or six carbons linked together in a ring. There’s no need to dive deep into organic chemistry, but there are a couple of essential things to know to interpret the standard representations of these molecules.
Check out the sugars depicted in the figure. The top-left molecule, glucose, has six carbons, which have been numbered. The sugar to its right is the same glucose, with all but one “C” removed. The other five carbons are still there but are inferred using the conventions of organic chemistry: Anywhere there is a corner, there’s a carbon unless otherwise indicated. It might be a good exercise for you to add in a “C” over each corner so that you gain a good understanding of this convention. You should end up adding in five carbon symbols; the sixth is already given because that is conventionally included when it occurs outside of the ring.
On the left is a glucose with all of its carbons indicated. They’re also numbered, which is important to understand now for information that comes later. On the right is the same molecule, glucose, without the carbons indicated (except for the sixth one). Wherever there is a corner, there is a carbon, unless otherwise indicated (as with the oxygen). On the bottom left is ribose, the sugar found in RNA. The sugar on the bottom right is deoxyribose. Note that at carbon 2 (*), the ribose and deoxyribose differ by a single oxygen.
The lower left sugar in the figure is a ribose. In this depiction, the carbons, except the one outside of the ring, have not been drawn in, and they are not numbered. This is the standard way sugars are presented in texts. Can you tell how many carbons there are in this sugar? Count the corners and don’t forget the one that’s already indicated!
If you said “five,” you are right. Ribose is a pentose (pent = five) and happens to be the sugar present in ribonucleic acid, or RNA. Think to yourself what the sugar might be in deoxyribonucleic acid, or DNA. If you thought, deoxyribose, you’d be right.
The fourth sugar given in the figure is a deoxyribose. In organic chemistry, it’s not enough to know that corners indicate carbons. Each carbon also has a specific number, which becomes important in discussions of nucleic acids. Luckily, we get to keep our carbon counting pretty simple in basic biology. To count carbons, you start with the carbon to the right of the non-carbon corner of the molecule. The deoxyribose or ribose always looks to me like a little cupcake with a cherry on top. The “cherry” is an oxygen. To the right of that oxygen, we start counting carbons, so that corner to the right of the “cherry” is the first carbon. Now, keep counting. Here’s a little test: What is hanging down from carbon 2 of the deoxyribose?
If you said a hydrogen (H), you are right! Now, compare the deoxyribose to the ribose. Do you see the difference in what hangs off of the carbon 2 of each sugar? You’ll see that the carbon 2 of ribose has an –OH, rather than an H. The reason the deoxyribose is called that is because the O on the second carbon of the ribose has been removed, leaving a “deoxyed” ribose. This tiny distinction between the sugars used in DNA and RNA is significant enough in biology that we use it to distinguish the two nucleic acids.
In fact, these subtle differences in sugars mean big differences for many biological molecules. Below, you’ll find a couple of ways that apparently small changes in a sugar molecule can mean big changes in what it does. These little changes make the difference between a delicious sugar cookie and the crunchy exoskeleton of a dung beetle.
Sugar and Fuel
A marathon runner keeps fuel on hand in the form of “carbs,” or sugars. These fuels provide the marathoner’s straining body with the energy it needs to keep the muscles pumping. When we take in sugar like this, it often comes in the form of glucose molecules attached together in a polymer called starch. We are especially equipped to start breaking off individual glucose molecules the minute we start chewing on a starch.
Double X Extra: A monomer is a building block (mono = one) and a polymer is a chain of monomers. With a few dozen monomers or building blocks, we get millions of different polymers. That may sound nutty until you think of the infinity of values that can be built using only the numbers 0 through 9 as building blocks or the intricate programming that is done using only a binary code of zeros and ones in different combinations.
Our bodies then can rapidly take the single molecules, or monomers, into cells and crack open the chemical bonds to transform the energy for use. The bonds of a sugar are packed with chemical energy that we capture to build a different kind of energy-containing molecule that our muscles access easily. Most species rely on this process of capturing energy from sugars and transforming it for specific purposes.
Polysaccharides: Fuel and Form
Plants use the Sun’s energy to make their own glucose, and starch is actually a plant’s way of storing up that sugar. Potatoes, for example, are quite good at packing away tons of glucose molecules and are known to dieticians as a “starchy” vegetable. The glucose molecules in starch are packed fairly closely together. A string of sugar molecules bonded together through dehydration synthesis, as they are in starch, is a polymer called a polysaccharide (poly = many; saccharide = sugar). When the monomers of the polysaccharide are released, as when our bodies break them up, the reaction that releases them is called hydrolysis.
Double X Extra: The specific reaction that hooks one monomer to another in a covalent bond is called dehydration synthesis because in making the bond–synthesizing the larger molecule–a molecule of water is removed (dehydration). The reverse is hydrolysis (hydro = water; lysis = breaking), which breaks the covalent bond by the addition of a molecule of water.
Although plants make their own glucose and animals acquire it by eating the plants, animals can also package away the glucose they eat for later use. Animals, including humans, store glucose in a polysaccharide called glycogen, which is more branched than starch. In us, we build this energy reserve primarily in the liver and access it when our glucose levels drop.
Whether starch or glycogen, the glucose molecules that are stored are bonded together so that all of the molecules are oriented the same way. If you view the sixth carbon of the glucose to be a “carbon flag,” you’ll see in the figure that all of the glucose molecules in starch are oriented with their carbon flags on the upper left.
The orientation of monomers of glucose in polysaccharides can make a big difference in the use of the polymer. The glucoses in the molecule on the top are all oriented “up” and form starch. The glucoses in the molecule on the bottom alternate orientation to form cellulose, which is quite different in its function from starch.
Storing up sugars for fuel and using them as fuel isn’t the end of the uses of sugar. In fact, sugars serve as structural molecules in a huge variety of organisms, including fungi, bacteria, plants, and insects.
The primary structural role of a sugar is as a component of the cell wall, giving the organism support against gravity. In plants, the familiar old glucose molecule serves as one building block of the plant cell wall, but with a catch: The molecules are oriented in an alternating up-down fashion. The resulting structural sugar is called cellulose.
That simple difference in orientation means the difference between a polysaccharide as fuel for us and a polysaccharide as structure. Insects take it step further with the polysaccharide that makes up their exoskeleton, or outer shell. Once again, the building block is glucose, arranged as it is in cellulose, in an alternating conformation. But in insects, each glucose has a little extra added on, a chemical group called an N-acetyl group. This addition of a single functional group alters the use of cellulose and turns it into a structural molecule that gives bugs that special crunchy sound when you accidentally…ahem…step on them.
These variations on the simple theme of a basic carbon-ring-as-building-block occur again and again in biological systems. In addition to serving roles in structure and as fuel, sugars also play a role in function. The attachment of subtly different sugar molecules to a protein or a lipid is one way cells communicate chemically with one another in refined, regulated interactions. It’s as though the cells talk with each other using a specialized, sugar-based vocabulary. Typically, cells display these sugary messages to the outside world, making them available to other cells that can recognize the molecular language.
Lipids: The Fatty Trifecta
Starch makes for good, accessible fuel, something that we immediately attack chemically and break up for quick energy. But fats are energy that we are supposed to bank away for a good long time and break out in times of deprivation. Like sugars, fats serve several purposes, including as a dense source of energy and as a universal structural component of cell membranes everywhere.
Fats: the Good, the Bad, the Neutral
Turn again to a nutrition label, and you’ll see a few references to fats, also known as lipids. (Fats are slightly less confusing that sugars in that they have only two names.) The label may break down fats into categories, including trans fats, saturated fats, unsaturated fats, and cholesterol. You may have learned that trans fats are “bad” and that there is good cholesterol and bad cholesterol, but what does it all mean?
Let’s start with what we mean when we say saturated fat. The question is, saturated with what? There is a specific kind of dietary fat call the triglyceride. As its name implies, it has a structural motif in which something is repeated three times. That something is a chain of carbons and hydrogens, hanging off in triplicate from a head made of glycerol, as the figure shows. Those three carbon-hydrogen chains, or fatty acids, are the “tri” in a triglyceride. Chains like this can be many carbons long.
Double X Extra: We call a fatty acid a fatty acid because it’s got a carboxylic acid attached to a fatty tail. A triglyceride consists of three of these fatty acids attached to a molecule called glycerol. Our dietary fat primarily consists of these triglycerides.
Triglycerides come in several forms. You may recall that carbon can form several different kinds of bonds, including single bonds, as with hydrogen, and double bonds, as with itself. A chain of carbon and hydrogens can have every single available carbon bond taken by a hydrogen in single covalent bond. This scenario of hydrogen saturation yields a saturated fat. The fat is saturated to its fullest with every covalent bond taken by hydrogens single bonded to the carbons.
Saturated fats have predictable characteristics. They lie flat easily and stick to each other, meaning that at room temperature, they form a dense solid. You will realize this if you find a little bit of fat on you to pinch. Does it feel pretty solid? That’s because animal fat is saturated fat. The fat on a steak is also solid at room temperature, and in fact, it takes a pretty high heat to loosen it up enough to become liquid. Animals are not the only organisms that produce saturated fat–avocados and coconuts also are known for their saturated fat content.
The top graphic above depicts a triglyceride with the glycerol, acid, and three hydrocarbon tails. The tails of this saturated fat, with every possible hydrogen space occupied, lie comparatively flat on one another, and this kind of fat is solid at room temperature. The fat on the bottom, however, is unsaturated, with bends or kinks wherever two carbons have double bonded, booting a couple of hydrogens and making this fat unsaturated, or lacking some hydrogens. Because of the space between the bumps, this fat is probably not solid at room temperature, but liquid.
You can probably now guess what an unsaturated fat is–one that has one or more hydrogens missing. Instead of single bonding with hydrogens at every available space, two or more carbons in an unsaturated fat chain will form a double bond with carbon, leaving no space for a hydrogen. Because some carbons in the chain share two pairs of electrons, they physically draw closer to one another than they do in a single bond. This tighter bonding result in a “kink” in the fatty acid chain.
In a fat with these kinks, the three fatty acids don’t lie as densely packed with each other as they do in a saturated fat. The kinks leave spaces between them. Thus, unsaturated fats are less dense than saturated fats and often will be liquid at room temperature. A good example of a liquid unsaturated fat at room temperature is canola oil.
A few decades ago, food scientists discovered that unsaturated fats could be resaturated or hydrogenated to behave more like saturated fats and have a longer shelf life. The process of hydrogenation–adding in hydrogens–yields trans fat. This kind of processed fat is now frowned upon and is being removed from many foods because of its associations with adverse health effects. If you check a food label and it lists among the ingredients “partially hydrogenated” oils, that can mean that the food contains trans fat.
Double X Extra: A triglyceride can have up to three different fatty acids attached to it. Canola oil, for example, consists primarily of oleic acid, linoleic acid, and linolenic acid, all of which are unsaturated fatty acids with 18 carbons in their chains.
Why do we take in fat anyway? Fat is a necessary nutrient for everything from our nervous systems to our circulatory health. It also, under appropriate conditions, is an excellent way to store up densely packaged energy for the times when stores are running low. We really can’t live very well without it.
Phospholipids: An Abundant Fat
You may have heard that oil and water don’t mix, and indeed, it is something you can observe for yourself. Drop a pat of butter–pure saturated fat–into a bowl of water and watch it just sit there. Even if you try mixing it with a spoon, it will just sit there. Now, drop a spoon of salt into the water and stir it a bit. The salt seems to vanish. You’ve just illustrated the difference between a water-fearing (hydrophobic) and a water-loving (hydrophilic) substance.
Generally speaking, compounds that have an unequal sharing of electrons (like ions or anything with a covalent bond between oxygen and hydrogen or nitrogen and hydrogen) will be hydrophilic. The reason is that a charge or an unequal electron sharing gives the molecule polarity that allows it to interact with water through hydrogen bonds. A fat, however, consists largely of hydrogen and carbon in those long chains. Carbon and hydrogen have roughly equivalent electronegativities, and their electron-sharing relationship is relatively nonpolar. Fat, lacking in polarity, doesn’t interact with water. As the butter demonstrated, it just sits there.
There is one exception to that little maxim about fat and water, and that exception is the phospholipid. This lipid has a special structure that makes it just right for the job it does: forming the membranes of cells. A phospholipid consists of a polar phosphate head–P and O don’t share equally–and a couple of nonpolar hydrocarbon tails, as the figure shows. If you look at the figure, you’ll see that one of the two tails has a little kick in it, thanks to a double bond between the two carbons there.
Phospholipids form a double layer and are the major structural components of cell membranes. Their bend, or kick, in one of the hydrocarbon tails helps ensure fluidity of the cell membrane. The molecules are bipolar, with hydrophilic heads for interacting with the internal and external watery environments of the cell and hydrophobic tails that help cell membranes behave as general security guards.
The kick and the bipolar (hydrophobic and hydrophilic) nature of the phospholipid make it the perfect molecule for building a cell membrane. A cell needs a watery outside to survive. It also needs a watery inside to survive. Thus, it must face the inside and outside worlds with something that interacts well with water. But it also must protect itself against unwanted intruders, providing a barrier that keeps unwanted things out and keeps necessary molecules in.
Phospholipids achieve it all. They assemble into a double layer around a cell but orient to allow interaction with the watery external and internal environments. On the layer facing the inside of the cell, the phospholipids orient their polar, hydrophilic heads to the watery inner environment and their tails away from it. On the layer to the outside of the cell, they do the same.
As the figure shows, the result is a double layer of phospholipids with each layer facing a polar, hydrophilic head to the watery environments. The tails of each layer face one another. They form a hydrophobic, fatty moat around a cell that serves as a general gatekeeper, much in the way that your skin does for you. Charged particles cannot simply slip across this fatty moat because they can’t interact with it. And to keep the fat fluid, one tail of each phospholipid has that little kick, giving the cell membrane a fluid, liquidy flow and keeping it from being solid and unforgiving at temperatures in which cells thrive.
Steroids: Here to Pump You Up?
Our final molecule in the lipid fatty trifecta is cholesterol. As you may have heard, there are a few different kinds of cholesterol, some of which we consider to be “good” and some of which is “bad.” The good cholesterol, high-density lipoprotein, or HDL, in part helps us out because it removes the bad cholesterol, low-density lipoprotein or LDL, from our blood. The presence of LDL is associated with inflammation of the lining of the blood vessels, which can lead to a variety of health problems.
But cholesterol has some other reasons for existing. One of its roles is in the maintenance of cell membrane fluidity. Cholesterol is inserted throughout the lipid bilayer and serves as a block to the fatty tails that might otherwise stick together and become a bit too solid.
Cholesterol’s other starring role as a lipid is as the starting molecule for a class of hormones we called steroids or steroid hormones. With a few snips here and additions there, cholesterol can be changed into the steroid hormones progesterone, testosterone, or estrogen. These molecules look quite similar, but they play very different roles in organisms. Testosterone, for example, generally masculinizes vertebrates (animals with backbones), while progesterone and estrogen play a role in regulating the ovulatory cycle.
Double X Extra: A hormone is a blood-borne signaling molecule. It can be lipid based, like testosterone, or short protein, like insulin.
As you progress through learning biology, one thing will become more and more clear: Most cells function primarily as protein factories. It may surprise you to learn that proteins, which we often talk about in terms of food intake, are the fundamental molecule of many of life’s processes. Enzymes, for example, form a single broad category of proteins, but there are millions of them, each one governing a small step in the molecular pathways that are required for living.
Levels of Structure
Amino acids are the building blocks of proteins. A few amino acids strung together is called a peptide, while many many peptides linked together form a polypeptide. When many amino acids strung together interact with each other to form a properly folded molecule, we call that molecule a protein.
For a string of amino acids to ultimately fold up into an active protein, they must first be assembled in the correct order. The code for their assembly lies in the DNA, but once that code has been read and the amino acid chain built, we call that simple, unfolded chain the primary structure of the protein.
This chain can consist of hundreds of amino acids that interact all along the sequence. Some amino acids are hydrophobic and some are hydrophilic. In this context, like interacts best with like, so the hydrophobic amino acids will interact with one another, and the hydrophilic amino acids will interact together. As these contacts occur along the string of molecules, different conformations will arise in different parts of the chain. We call these different conformations along the amino acid chain the protein’s secondary structure.
Once those interactions have occurred, the protein can fold into its final, or tertiary structure and be ready to serve as an active participant in cellular processes. To achieve the tertiary structure, the amino acid chain’s secondary interactions must usually be ongoing, and the pH, temperature, and salt balance must be just right to facilitate the folding. This tertiary folding takes place through interactions of the secondary structures along the different parts of the amino acid chain.
The final product is a properly folded protein. If we could see it with the naked eye, it might look a lot like a wadded up string of pearls, but that “wadded up” look is misleading. Protein folding is a carefully regulated process that is determined at its core by the amino acids in the chain: their hydrophobicity and hydrophilicity and how they interact together.
In many instances, however, a complete protein consists of more than one amino acid chain, and the complete protein has two or more interacting strings of amino acids. A good example is hemoglobin in red blood cells. Its job is to grab oxygen and deliver it to the body’s tissues. A complete hemoglobin protein consists of four separate amino acid chains all properly folded into their tertiary structures and interacting as a single unit. In cases like this involving two or more interacting amino acid chains, we say that the final protein has a quaternary structure. Some proteins can consist of as many as a dozen interacting chains, behaving as a single protein unit.
A Plethora of Purposes
What does a protein do? Let us count the ways. Really, that’s almost impossible because proteins do just about everything. Some of them tag things. Some of them destroy things. Some of them protect. Some mark cells as “self.” Some serve as structural materials, while others are highways or motors. They aid in communication, they operate as signaling molecules, they transfer molecules and cut them up, they interact with each other in complex, interrelated pathways to build things up and break things down. They regulate genes and package DNA, and they regulate and package each other.
As described above, proteins are the final folded arrangement of a string of amino acids. One way we obtain these building blocks for the millions of proteins our bodies make is through our diet. You may hear about foods that are high in protein or people eating high-protein diets to build muscle. When we take in those proteins, we can break them apart and use the amino acids that make them up to build proteins of our own.
How does a cell know which proteins to make? It has a code for building them, one that is especially guarded in a cellular vault in our cells called the nucleus. This code is deoxyribonucleic acid, or DNA. The cell makes a copy of this code and send it out to specialized structures that read it and build proteins based on what they read. As with any code, a typo–a mutation–can result in a message that doesn’t make as much sense. When the code gets changed, sometimes, the protein that the cell builds using that code will be changed, too.
Biohazard!The names associated with nucleic acids can be confusing because they all start with nucle-. It may seem obvious or easy now, but a brain freeze on a test could mix you up. You need to fix in your mind that the shorter term (10 letters, four syllables), nucleotide, refers to the smaller molecule, the three-part building block. The longer term (12 characters, including the space, and five syllables), nucleic acid, which is inherent in the names DNA and RNA, designates the big, long molecule.
DNA vs. RNA: A Matter of Structure
DNA and its nucleic acid cousin, ribonucleic acid, or RNA, are both made of the same kinds of building blocks. These building blocks are called nucleotides. Each nucleotide consists of three parts: a sugar (ribose for RNA and deoxyribose for DNA), a phosphate, and a nitrogenous base. In DNA, every nucleotide has identical sugars and phosphates, and in RNA, the sugar and phosphate are also the same for every nucleotide.
So what’s different? The nitrogenous bases. DNA has a set of four to use as its coding alphabet. These are the purines, adenine and guanine, and the pyrimidines, thymine and cytosine. The nucleotides are abbreviated by their initial letters as A, G, T, and C. From variations in the arrangement and number of these four molecules, all of the diversity of life arises. Just four different types of the nucleotide building blocks, and we have you, bacteria, wombats, and blue whales.
RNA is also basic at its core, consisting of only four different nucleotides. In fact, it uses three of the same nitrogenous bases as DNA–A, G, and C–but it substitutes a base called uracil (U) where DNA uses thymine. Uracil is a pyrimidine.
DNA vs. RNA: Function Wars
An interesting thing about the nitrogenous bases of the nucleotides is that they pair with each other, using hydrogen bonds, in a predictable way. An adenine will almost always bond with a thymine in DNA or a uracil in RNA, and cytosine and guanine will almost always bond with each other. This pairing capacity allows the cell to use a sequence of DNA and build either a new DNA sequence, using the old one as a template, or build an RNA sequence to make a copy of the DNA.
These two different uses of A-T/U and C-G base pairing serve two different purposes. DNA is copied into DNA usually when a cell is preparing to divide and needs two complete sets of DNA for the new cells. DNA is copied into RNA when the cell needs to send the code out of the vault so proteins can be built. The DNA stays safely where it belongs.
RNA is really a nucleic acid jack-of-all-trades. It not only serves as the copy of the DNA but also is the main component of the two types of cellular workers that read that copy and build proteins from it. At one point in this process, the three types of RNA come together in protein assembly to make sure the job is done right.
Post-Thanksgiving links: All about food…or sorta food
You made it through Thanksgiving even though you ran out of vanilla extract? Let science help you out the next time you fall short of that one important ingredient. Scientists have compiled a list of suitable substitutes for cooks everywhere.
Did you wake up this morning with fingers twice their normal size? Find out where the salt was in that Thanksgiving meal.
Asking, “Are you improbable or inevitable?”, Robert Krulwich tells us that the math determines that we are improbable. But we’re here, so aren’t we…inevitable?
Have you read about “the gene” for ADHD or the “drinking gene”? Stop reading that bad writing! There’s a difference between a trait that a gene confers and the many, many ways someone can manifest that trait. Read more from David Dobbs over at Neuron Culture in “Enough with the ‘slut gene’ already: Behaviors ain’t traits.”
Speaking of how scientists might spend their days, how about spending them watching 400 YouTube videos of dogs chasing their tails? Via DiscoBlog at Discover Science.
Use this app to follow live cameras trained on the wild places animals live in Sri Lanka, Kenya, the UK, and other places. When you spot an animal, identify it for science. Via GeekDad at Wired, Citizen science from Instant Wild! The featured Webcam as we posted these links had captured a porcupine in action.
Maybe you’ve never been in a lab in your life and wouldn’t know PCR from a VCR. That doesn’t matter when you watch this video of stop-motion animation using thousands and thousands of the tiny tubes scientists use when they conduct PCR (polymerase chain reaction). The video is actually a promotional video from vendors of equipment for this kind of lab test.
Conditions in Antarctica are almost unimaginable inhospitable for humans, yet scientists visit there yearly to conduct valuable research. Valuable, dangerous research, but the scenery? Stunning. Via BoingBoing.
The brain is encased in a skull for protection, with a nice fluid surrounding it for extra cushioning. But the human brain was never meant to endure years of the Newtonian physical pounding that comes with playing football. Now, researchers are beginning a brain study to test the brains of 100 former National Football League players to see what harm has been done and how to identify it early. Watch the video below. Imagine the brains inside those skulls. Recall that for every action, there is an equal and opposite reaction. Yikes.
You’ve done it. We’ve done it. You walk from one room to another on a mission and when you get into the other room…you forget why you’re there. Now, instead of blaming age, you can blame the door.
Look around: Do you a see a lot of stuff you just can’t bring yourself to throw away? Read this.
When it comes to sex–studies of it, studies of how it develops–males get a lot of the attention, and the female sex has even (gasp) been referred to as the “default” sex, as in, if there aren’t signals to become male, then females develop by default. That ain’t true, and as it turns out, females have a pathway dedicated to developing and maintaining them just as males do. So there, scientists.
Is it hard for women to self promote? This one is about academe, but it applies across many work places.
You may have read about this person’s efforts to perform a butt injection on a woman using “Fix a Flat.” It’s probably best to just love your butt for what it is, which isn’t Fix a Flat.
In smarter news, NASA is rolling out Aspire 2 Inspire, targeting girls interested in science. Know a girl who’s interested in science? You can start with the Aspire 2 Inspire video below about women in science:
“Yet more must be done to address the projected shortfall of 280,000 math and science teachers that our nation will face by 2015. We need public and private investments in math and science education and we need a commitment to making a difference on a national scale.”