Jennifer Canale is a Senior Microbiologist for the United States Food and Drug Administration (FDA) in Queens, NY, as well as an adjunct microbiology lecturer for City University of NY (York College and College of Staten Island). Jennifer is also passionate about promoting women in science and leads an annual women in science event at the FDA as a means to promote awareness about gender discrimination in the workplace. [DXS] First, can you give me a quick overview of what your scientific background is and your current connection to science?
[JC] I have always been interested in science, and since most of my family worked in Bellvue Hospital, I was very comfortable around people in lab coats. In the early seventies, at the age of 5, I announced to my grandfather, the X-ray technician, and his brothers (my great uncles) that I wanted to become a doctor, specifically a doctor that delivers babies.
My grandfather was proud and my uncles were dismayed. My uncle Joe said to me, “Jennifer, you mean a nurse like your cousin Joanie, right?” My cousin Joan applied to Medical School in the sixties and the same group of uncles convinced her that her fiancé, Warren, wouldn’t wait 4 years to get married and it was more lady-like to be a nurse. Today she is a retired left-handed OR nurse that specializes in cracking open chests for cardiac surgery, not so lady-like after all. So in an attempt to not have a repeat of Joanie, my grandfather jumped to my defense against his brothers and said that ‘she can be a doctor if she wanted to be’, and, furthermore, his niece Joanie was smarter and more capable than most of the doctors he worked with and shouldn’t have had to take orders from them.
My uncles agreed that there was no question of the intellectual prowess possessed by both Joanie and myself, and their reluctance came out of concern for me. They worked in the hospital, too, and saw how male doctors would abuse the female ones and make their lives more difficult because they didn’t want to allow girls in the all-boys club. “Do you want our baby – our most precious blood – to have to fight her whole life for this? What about the family – how will she find a husband and bring us more children if she sticks her nose in a book the rest of her life?” These arguments sounded a lot better when they were stated in Sicilian. Back then, the concept of ‘women can have it all’ – work and family – was not the norm like it is today.
My grandfather came back with his final answers to them. I was his granddaughter, I looked just like him, I was a fighter just like him, and this is America and she will be what she wants to be, ‘End of Story’. My uncles agreed that I was his granddaughter, I looked just like him, and I was a stubborn mule just like him, so he was probably right and they would pray for me and secretly hope I would change my mind.
Now this all transpired in front of me in a combination of English and Sicilian while I stood there in my denim overalls with a Tweety Bird patch. I was listening, and since I was only beginning to learn Sicilian, I only caught a couple of words: blood, children, book, change, and I misunderstood the word for fighter as “afraid.” I added to my grandfather’s “end of story” remark that I was not afraid of blood, I can learn how to deliver children from a book, and questioned why they wanted me to change- those overalls were my favorite!
My family was supportive to a point, but when I asked for an erector set for Christmas, I got a Barbie town house. When I wanted to go camping with the Girl Scouts, I was sent to dance school (but, much to my amazement, I enjoyed that until I was 17). My parents started giving in around 3rdgrade, and I got the panda bear-shaped calculator I wanted, as well as the robot toy 2XL featuring the 8-track tape. My mom would beg me to watch Little House On the Prairie, but I preferred Star Trek (the original Kirk version), Lost in Space (Danger Will Robinson), and Land of the Lost. Of course this was all my dad’s fault according to mom – he was the sci-fi guy, but he always said, “Jen was born this way!”
My parents eventually gave up, and my uncles kept praying for that change of mind, but I spent the late seventies and early eighties winning science fairs with experiments my Uncle Ben, the electrician, rigged for me. They thought there was hope for me to be more “lady-like” in 1984 when I started high school and wanted to try out for the cheerleading squad, but the teachers advised me that “the cheer squad” was no place for an “honor student” like me. So it was off to advanced placement Biology and Chemistry, and by graduation in 1988, I was accepted to the pre-med program at NYU.
I graduated from NYU with honors, and my parents got me two presents: my name in diamonds and a stethoscope. My grandfather bought me a set of crisp white lab coats and gloated to his brothers with a cigar in his mouth. Apparently a bet was made amongst them and from hence forward they had to call me “doctoressa,” the hybrid feminized version of doctor in Italian.
The NYU pre-med was highly competitive – a constant process of elimination from 500 students (1:3, female:male) down to only 109 of us actually completing the program. The men thought it was strategic to flirt with the girls and convince us that we shouldn’t become doctors but instead should marry them. The guy that told me that got a punch in the stomach – in the name of the other women that worked. It was also apparent that many were planting the seeds of doubt in the pre-med females, stating that if we became doctors, then we wouldn’t be able to have a family. In essence, we were being told that we would be giving up the chance to have children. You had to go against your “true female nature” to breed and nurture and (instead) become a selfish and testosterone-like human to make it in this field. That was the nail in the coffin for a lot of the women in my program. The most brutal tactic and final blow to confidence was when I heard someone say that “only the ugly girls become doctors because no man would want them.”
In the nineties – halfway through college – I did change my mind, and my uncles were dancing in the streets. They thought I met a nice boy in college and I was going to settle down, give them more kids, and make sauce and meatballs on a Sunday like the good Paesana I was supposed to be. I announced I didn’t want to be an MD anymore, I wanted to be a PhD, instead. I wanted to be a SCIENTIST, do research, and maybe teach in a university. A “Scientista”-“Professoressa” “Aiuta Dio” (which means help us god)! Back to church and the rosary beads. When I got my master’s degree in microbiology, the family was just convinced I liked to collect graduation hats.
There was a feeling among my family members that science was a “boy thing,” and my cousins teased me as a result. They considered me a nerd and less feminine than my other girl cousins. I was told that I would never get married and have kids because I am a bookworm. Even in the mid-’90s, I had friends that told me not to tell guys that I was a scientist because they wouldn’t ask me out. I was kind of cute and only told a guy the truth about my profession if we got serious. As an experiment, I told one guy I met that I was a scientist and he said I looked too sexy to be that smart – and then he walked away.
I met discrimination on both sides of the stereotypical coin, in academia and in the work force. I was told when I was interviewing for graduate schools (and then for science jobs) that I had several strikes against me. First, strike one, my thick Staten Island/ Brooklyn accent supposedly made me sound less intelligent. My mentor in graduate school, Dr. Mark Albano, said to tell people to kiss your “you know what” because as long as I could discuss topics like “molecular genetics” who cares how it sounds. Besides he found my accent endearing, especially because it made boring topics sound more interesting.
Strike two was my long hair. I was told that my long hair was not practical in a scientific environment, and if I looked too glamorous on interviews I would not be taken seriously. I put my hair in a bun and toned down my make-up, but I didn’t cut it. Apparently, I looked too feminine, especially given my major curves, and even my power suits could not hide that. Women at the time were dressing very masculine (think early Miranda on Sex in the City) to compete with men for jobs. When I got the interview for my first job with Dr. Moretti in the Reproductive Immunology Lab at St. Vincent’s Medical Center in Staten Island, I remember wearing a black and white houndstooth print sheath dress with a matching short suit jacket, accessorized with pearls. Dr. Moretti said I was like Rosalind Franklin and Jackie Kennedy all rolled up into one, with a side order of cannoli.
The early 2000s arrived, and attitudes toward science changed. Shows like CSI became wildly popular. Science fiction movies about transforming robots became blockbusters. People began to use technology in their everyday lives, such as smart phones, tablets, and car navigation systems, and it suddenly became “cool.” I met my husband in 1999, and since I really was into him, I told him the truth about being a “microbiologist” from the start. He said, and I quote, “Wow, your smart, sexy, and Sicilian – it’s like I hit the Lotto!”
My wedding was the most joyful event in our family’s history because most of them thought that would never happen. I still get teased by my family when I give a long, drawn out scientific explanation of something or when I bake and make exact measurements of ingredients with my Pyrex bakeware with both the ounces and metric conversions. My husband responds for me and says “he learns something new everyday and hopes that our son becomes a nerd just like his mommy.”
So now I have it all: I am a female scientist, a wife, and a mother, even though others didn’t think that would be possible. But I always knew it would happen. I understood and forgave my uncles because I knew that they wanted to protect me, not hinder me. As for all my doubters I regularly take Dr. Albano’s advise and tell them to kiss my “you know what!”
Even my current supervisor, Maureen Coakley, recently told me in an interview that I am an “anomaly,” meaning that I am a flamboyant scientist. That was one of the best compliments I ever received. I am who I am, and that is why my playlist on my iPhone has the “Big Bang Theory Theme Song” followed by “I’m sexy and I know it!”
Times have changed. Perceptions have altered in a good way, but not entirely. Lesson learned from both academia and the school of life is that some people will get you and some people won’t. If they don’t, don’t take it personally because it is their loss and their ignorance. Some people see the person, and some see the stereotype. All you can do is try to educate them in an attempt to bust the stereotype. The only perception that matters is how you perceive yourself and use that perception as a means to become the woman that you were meant to be.
[DXS] What ways do you express yourself creatively that may not have a single thing to do with science?
[JC]Ever since planning my wedding in 2004, I have been interested in event planning. I have a knack at coordinating events, which I do as part of my collateral duties at FDA, where I have served as the Women’s Program Coordinator for the past 9 years. People call me the “Fun Fairy” because I can be very creative and take any topic, put a different and interesting spin on it, and present it to a group in very entertaining ways. My creativity is driven by my intellectualism, and I incorporate that into something fun and memorable. I always make little inexpensive favors – buy them to give out to my audience – that are”theme oriented,” and they keep them as a reminder of the event.
The people I work with have whole collections of these favors, and they remember what each one stands for. For instance, the Women’s History Month theme for one year was “Our History is Our Strength.” Before planning this event, I had attended at NYU the Satellite Summit of National Women’s Conference hosted by Maria Shriver (then 1st Lady of California) and the First Lady, Michelle Obama. So I thought I would highlight the contributions of the First Ladies to US history. I found an educational video on the history of the First Ladies, did a presentation on the Satellite Summit, and even had a fashion show featuring of reproductions of Jacqueline Kennedy jewelry collection (my favorite first lady). I used the symbol of a “Cameo” to represent the first ladies, and so I made a huge paper one with beads on tulle on my bulletin board with pictures of the first ladies around it and gave out cameo bracelets that I made from gluing plastic cameo buttons on ribbon. Everyone still has a cameo on their desk at work, occasionally conjuring up memories of my First Ladies event.
[DXS] Do you find that your scientific background informs your creativity, even though what you do may not specifically be scientific?
[JC]My entire life is influenced by, or even revolves around, “Science.” I love science fiction movies, books, comic books, etc. Any inspiration I get for any of my creative projects always has some root in something “science-related.” I also think that my background in science helps make my visions come to life. Even the smallest details like the stemware I chose for my wedding was a Mikasa pattern that resembled a DNA double helix, or a hexagonal candleholder that looked like a benzene ring (at least it did to me!). Another example comes from my Women’s Program, when the theme was “Writing Women Back Into History.” So I found a book called The Women of Apollo, which gave the untold story of the women engineers who had critical contributions to the Apollo Space programs. For me, all roads lead back to science.
[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?
[JC]I have experienced both negative and positive views by others when I am expressing my self creatively. On one hand, there were people that associate planning events with a negative stereotype of being a “party-girl” or “bimbo” type that cares more about the “girly fun” stuff than the serious business of science. On the other hand, there have been people who constantly praise me for presenting science-related topics in entertaining ways. The latter view me as a “flamboyant scientist” who shares her knowledge in an interesting manner. In this life you will never please everyone; only seek to please yourself and your loved ones because those are the only opinions that matter.
[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?
[JC]In planning these events, I have come up with a formula of sorts to create a successful soirée. Of course, this formula is an entire science in itself. I have to consider things like timing, lighting, printed materials (programs, table cards, menus, etc.) and a gamut of other things that involve an understanding of science. I am a biologist with a minor in chemistry, but the more I do these events, the more I get into things like astronomy (for a celestial-themed wedding, for instance). I mention lighting, which seems so simple, because it is actually quite complicated – getting the right reflections and materials to use (i.e.- LEDs, wax candles vs. battery operated, the limitations of pyrotechnics in party venues) is critical. Even in doing crafts for favors and printed materials, like event programs, I’ve learned different scientific techniques, such the right kind of bonding agent to use to attach ribbons, charms, or vinyl decorations, or even the use of edible ink in printers to make fondant or wafer decorations to put on cupcakes or cakes. It is a continuous learning experience.
[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?
[JC]I am comfortable with expressing my femininity in the way I dress and conduct myself in any setting. Although, many years ago, I was advised to dress in suits and tailored shirts similar to a man and wear neutral make-up or none at all if I wanted to be taken seriously in the scientific world, I went against the grain. I am a curvy girl, and there is no hiding my femininity. So I embrace it. I wore suits, but nothing drab – always something like a red or purple skirt suit with heels. I adhere to work environment rules like no open toe shoes in the lab, which is a safety concern, but I do not downplay my female attributes to fit in, or to present a more palatable image to my scientific peers. I do not concern myself with people’s perceptions of me based on my looks because once I “speak” and “communicate” scientific concepts, there is no question of my prowess. I am what I am, and that is a female scientist, and I pride myself in being a “stereotype buster.”
[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?
[JC]I think that being the “flamboyant scientist” works in my favor, and as a science communicator, it is effective all aspects of my life. As an adjunct professor, my students often thank me for making science fun and understandable. As a scientist, my colleagues and interns find my training methods to be memorable and actually increase their understanding of the job. As the Women’s Program Coordinator at the FDA, I create unforgettable events that people look forward to and learn a lot from. As a wife, mother, daughter, aunt, cousin, and friend, I am the “Fun Fairy” (pictured with wings and a lab coat), and their lovable nerdy girl.
I feel my true gift is being able to communicate science. My mentor in graduate school always told me I had the talent of taking complicated scientific ideas and expressing them in a way that anyone could understand. I have some ideas brewing involving science books for children and teens, and I would like to explore these avenues in order to share this gift with others. I would also like to get involved in maybe writing for popular science publications, if given the opportunity.
[DXS] If you had something you could say to the younger you about the role of expression and creativity in your chosen career path, what would you say?
[JC]I would say be true to yourself. Whatever path you take career-wise, always remember that is could be something you will be doing the rest of your life. Yes, there are financial considerations to make, but if you do not have that creative outlet incorporated into your career, then you will be miserable. I am the happiest at work when I am planning a Women’s Program alongside doing experiments or going to my second job as a professor at York College. You need the creativity to keep the blood flowing. Where would science be without creativity? Find what your talent is and what makes you happy, and then apply it to your career. That is the secret to success.
It’s not easy being green. First, you have decide which green to be. (Source)
[We at Double X Science had been considering a “toxins” post but then found the following post by Jennifer Mo, a happily childfree vegetarian who lives in California with a cat named Brie but variously nicknamed Walnut “for her brain capacity” or Toxokitty for her history of toxoplasmosis–which, as it turns out, turns up in Jennifer’s guest post, below. This post first appeared at Jennifer’s blog, It’s Not Easy to Be Green, where she writes about environmental issues as a “rationalist and a pragmatist.” You can also follow Jennifer on Twitter @noteasy2begreen. We appreciated the pragmatics of this particular post quite a bit and thank Jennifer for allowing us to host it at Double X Science. We are particularly taken with the fact that she asks if we’d ever wanted to call our own brain a troglodyte.]
It’s a common demand from the public to scientists: prove to us something is safe before unleashing your monster on the world. And on one hand, it’s a totally fair, reasonable request to not be treated as lab rats. I get that. I hate the idea of having big chemical corporations profiting off their creations that create long term problems for ordinary people and the environment. On the other, whether you’re talking about GMOs or synthetic chemicals, it’s a problematic request for a couple of key reasons:
It assumes a binary between safe and unsafe without regard to exposure level or other circumstances. Just about everything can be harmful under the right (or perhaps I should say wrong?) conditions. Take water, for example.TonsContinue reading →
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.
So, let’s take cancer out of the picture and discuss hysterectomy for non-cancerous (benign) reasons.
First of all. A hysterectomy (removing the uterus) can be done via one of these four methods:
Vaginal, a small incision at the top of the vagina and the uterus is removed entirely through the vagina without any incision on the abdomen.
Laparoscopic surgery, where incisions are made in the belly and an operating telescope is inserted. The uterus is then removed either through a small incision in the belly wall or through the vagina.
A robotic surgery, which is laparoscopic surgery (see #2) performed with specialized equipment. The surgeon actually sits at a consult and operates the equipment remotely. An assistant is scrubbed in during the case to help with the equipment.
An abdominal hysterectomy. This requires an incision in the belly and has much longer recovery times than the other 3 options. This is what most people visualize when they think of surgery.
The American Congress of OB/GYN (ACOG) recommends vaginal hysterectomy as the least invasive method (least invasive is almost always the best option) with the best outcomes. Sometimes a vaginal hysterectomy isn’t feasible for technical reasons and then a laparoscopic approach is favored. There is no study that suggests a robotic hysterectomy offers any medical advantage over a vaginal or a laparoscopic hysterectomy when cancer isn’t the reason for the surgery.
So if there is no advantage to robotic hysterectomies, why are gynecologists pushing them? And make no mistake, they are pushing them as 3 years ago 0.5% of hysterectomies were robotic and now that number has soared exponentially to 10% (JAMA, 2013)
Why this exponential increase? I can think of four reasons:
They need the practice. The gynecologists want to learn the new technique (see the marketing angle below), but it takes quite a few cases to get good.
A marketing tool. Hey, robots are cool, they’re new, they must be better! People will want robots.
Hospitals are pushing GYNs to use the surgical robot, the robot that cost about $1.7 million to buy in addition to $125,000 in annual maintenance. Hospitals need to keep the robot in use to cover these expenses. That money can only come from your insurance company, your tax dollars (Medicaid and Medicare), or directly from you.
They don’t know the literature and believe the hype from the reps who sell the robots.
Robotic surgery is not the only or the best minimally invasive approach for hysterectomy. Nor is it the most cost-efficient. It is important to separate the marketing hype from the reality when considering the best surgical approach for hysterectomies
…there is no good data proving that robotic hysterectomy is even as good as—let alone better—than existing, and far less costly, minimally invasive alternatives.
A robot adds $2000 to a hysterectomy.If every non-cancer (benign) hysterectomy in the United States were performed with a robot, ACOG estimates that $960 million to $1.9 billion will be added to the health care system each year.
If your GYN is recommending robotic surgery over a vaginal or a traditional laparoscopic hysterectomy and you don’t have cancer, you need to ask, “Why?” (and take a look to see if robotic surgery is featured prominently on the web page and the practice’s marketing).
New technology isn’t always better. While a robot can lead to improved outcomes for complex cancer cases (they allow the surgeon to do the case with a laparoscopically rather than with a big incision), using a robot for a benign hysterectomy is like driving a Ferrari with the speedometer set so the car can’t exceed 15 miles an hour. It might look cooler, but it’s going to cost you a lot more up front and in maintenance and it’s not going to get you around the city any faster or safer than a Honda.
We are all stewards of the health care system. Wasting $2000 per patient on the costs to run a robot for a benign hysterectomy is simply funding the salaries of the people who sell surgical robots and increasing the cost of health care for everyone else, because we all pay when care becomes more expensive with higher premiums and co-payments.
Dr. Jennifer Gunter is an OB/GYN and a pain medicine physician who has authored the book, The Preemie Primer, a guide for parents of premature babies. In addition to her academic publications, her writing has appeared inUSA Today, the A Cup of Comfort series, KevinMD.com, EmpowHer.com, Exceptional Parent, Parents Press, Sacramento Parent, and the Marin Independent Journal.
Don’t start making plans to ignore those extra pounds just yet.
by Jennifer Gunter, MD, FRCS(C), FACOG, DABPM
This post first appeared at Dr. Gunter’s blog, where she wields the lasso of truth.
A new study published in the Journal of the American Medical Association (JAMA) indicates that a body mass index or BMI of 25-29.9 (overweight) is associated with the lowest risk of death and that class 1 obesity (BMI 30-34.9) is not associated with an increased risk of mortality. As this study hit the presses January 2nd (and I’m sure no editorial thought was given by JAMA to such a study coming out at the first of the year) when many people are thinking about weight loss resolutions, it was covered widely in the press and I read several op-eds claiming vindication for obesity. One op-ed on a major news site was indignant that CT scanners couldn’t accommodate a friend (some CT scanners have difficulty accommodating patients over 300 lbs). The author’s solution? Build bigger CT scanners because obesity isn’t bad at all. This new study proves it.
First of all the study doesn’t say that being overweight is good for you and that being an ideal weight is bad. What the study does tell us is that people who have a BMI of 35 or greater are more likely to die. This is not new information. A BMI of 35 is a lot of extra weight, depending on your height it could easily mean 70 extra pounds or more.15% of Americans have a BMI of 35 or greater.Only people with a BMI over 35, way over 35, need bigger CT scanners. I’m not saying that severely obese people shouldn’t have access to imaging studies, but the answer to the epidemic of severe obesity is not to claim vindication based on the inaccurate interpretation of one study and simply build bigger equipment.
What about the lower risk of death in the overweight and class 1 obesity groups compared with the normal BMI group? Well, this can be explained by a variety of factors:
The wrong control group. Many researchers question whether the control group should really be a BMI of 22-24.9, not the wider range of 18.5-24.9 used in this study. The reason, many people at the thinner end of the scale are thin because of illness and this obviously skews mortality statistics.
BMI is an imperfect tool with which to predict mortality when the result isn’t one extreme (< 18.5) or the other (>34.9). This is not a new finding. BMI just looks at weight, not the proportion of weight that is muscle mass vs. fatty tissue. Many people with a normal BMI have very little muscle mass and thus are carrying around excess fat and are less healthy than their BMI suggests. There are better metrics to look at mortality risk for people who have a BMI in the 18.5-34.9 range, such as waist circumference, resting heart rate, fasting glucose, leptin levels, and even DXA scans (just to name a few). The problem is that not all these measurement tools are practical on a large-scale.
A small amount of fat may provide an extra energy reserve for someone who becomes chronically ill, thus skewing the survival stats. For example, consider the dramatic weight loss associated with chemo…if you can’t eat due to extreme nausea and you have a little extra fat then you burn fat, but if you have no fat and can’t eat then you start breaking down muscle. This is a phenomenon has popped up in a few studies and definitely requires more research, because obesity is definitely associated with worse outcomes in many cancers.
Not all fat is created equal. Belly fat, the metabolically active muffin top, is what contributes to diabetes and other inflammatory conditions. Having a few extra pounds around the middle is far worse than having a few extra pounds on the hips. Again, not new information. BMI doesn’t distinguish between belly fat and thigh fat.
What is very important is that we don’t take erroneous messages from this study (hello, health reporters for major news outlets looking for attention-grabbing headlines). This study says nothing more than we need better tools than BMI to assess mortality risk for people who have a body mass index between 18.5 and 34.9 and that BMI doesn’t predict “ideal weight,” it only tells us that extremes are bad. This study also confirms that the 15% of Americans with a BMI of 35 are at increased risk of dying prematurely, a point sadly missed by many.
Body mass index simply doesn’t convey enough information to assess mortality risk for 85% of the population, but that fact (which isn’t new) shouldn’t stop each and every one of us from striving everyday to be the healthiest that we can be.
The name is irresistible: Cocktail Party Physics. What Jennifer Ouellette writes is also irresistible, especially if you have a love of physics with or without a deep grasp of it. What’s not to love about this intersection of popular culture, physics, and “the world at large” from someone who writes popular science books and describes herself as a “recovering English major”? That intersection has led Ouellette to expound on the scientific overlaps between a Stradivarius violin and CT scans. She’s written a wonderful long read on “science meets ghosts” that will make you a believer in one over the other. Whether it’s ghosts or more earthbound topics such as the relationship between Woody Woodpecker and football, Ouellette weaves the promised tapestry of the pop culture and physical science worlds. This year, Ouellette also bravely helmed the upcoming Open Lab 2011 book, serving as editor and managing a pile of hundreds of worthy entries into a sharp presentation of 51 of the best in science blogging for the year. A huge task, but the outcome is an overview of some of the best science writing on the web. Ouellette’s books include The Calculus Diaries: How Math Can Help You Lose Weight, Win in Vegas, and Survive a Zombie Outbreak (phew) and The Physics of the Buffyverse. Also, you had better conduct yourself well around her because she’s got a black belt in jujitsu, which I imagine she’s unafraid to use, and she’s married to a Time Lord. Or THE Time Lord, Caltech physicist and writer, Sean M. Carroll. Ouellette tweets under the nom d’Twitter JenLucPiquant, whom she describes as a “faux-French avatar with a penchant for gourmet cuisine, high fashion, existential angst, and dabbling in amateur scientific research of questionable import.” Nothing about her blog or other writing is questionable, and we urge a visit. Prepare to stay awhile.