Breathing, Only Harder

Harder to understand, anyway. It's cellular respiration time!

Cellular respiration is what we do with the oxygen we breathe in and the food we eat. It happens on a level that's beyond microscopic, and it happens about a kazillion times per second. Most importantly, it's going to be on my final exam, so let's poke at it a little.

The oxygen we breathe is produced by plants through the process of photosynthesis. We know from elementary school that plants use the power of sunlight (kind of like the power of friendship, only with fewer cupcakes) to turn carbon dioxide and water into oxygen. And that's true! But it's also an incomplete equation. It doesn't account for all of the molecules in play or the actual sunlight energy that activates photosynthesis. Besides oxygen, plants also create pure glucose (sugar), which they find delicious. (I do too. I've been known to eat brown sugar right out of the bag.)

Before I go on, let me explain something real quick about atoms. Atoms are the most basic unit of everything. An atom consists of a core surrounded by electrons, which are energized particles buzzing around the core in an orbit. (Picture Saturn.) These electrons are always in motion, though their energy levels can fluctuate. When atoms link up to form bigger substances, like a molecule of sugar or your keyboard, it generally means that they're sharing or swapping electrons around somehow and linking their orbits up with one another.

What did that have to do with anything? Well, the sunlight energy that kicks off photosynthesis also gives those electrons within that reaction a bit of a boost. The oxygen is released as a convenient byproduct, and the glucose that's formed as a result is linked together with high-energy chemical bonds. This becomes important when we start harvesting those turnips or bamboo shoots or kale or whatever, because those chemical bonds are what we're really after.

Yes, we eat chemical bonds. Bear with me.

So we eat our tempura. Once that glucose hits our system, we start doing a bunch of things to it. First, we have to break it down a little in a process called glycolysis (literally, breaking down glucose). This requires a teensy bit of an energy investment on our part, which is why you can hear stuff like "celery takes more energy to digest than you get out of it." That energy is added to the chemical bonds in the glucose, exciting them and making them unstable, which makes the glucose easier to break apart. We take that complex glucose molecule and break it down into two simpler halves. We add some other stuff, and so from one molecule of glucose we get two molecules of something called pyruvic acid. We also get a little return on our energy investment, but it's not much compared with what we're in for.

All that I just described--glycolysis--will happen no matter what as long as there's glucose and energy to spend. What follows is the part we need oxygen for, and the only reason we have to breathe.

Each of our cells has a structure called the mitochondria. The mitochondria are teensy energy factories, each one housing a process called the Krebs cycle. Pyruvic acid is the raw material for our mitochondria to work with. Through a long series of chemical reactions, helped along by vitamins (take 'em!), the pyruvic acid is shuffled around and systematically dismantled. There are a lot of steps to the Krebs cycle, and I won't go into them all, but the reason for it is so that we can squeeze every last atom out of the equation to use in our bodies.

And what exactly are we squeezing out? Believe it or not, hydrogen! It's the smallest, most basic element on the whole periodic table, but we're totally screwed without it. Throughout the Krebs cycle, a couple of different vitamins snatch up hydrogen, taking with them that energy we saw infused into the sugar when it was first made by photosynthesis. At the end of the process, all that's left is the carbon and oxygen parts of the equation, and we release that as carbon dioxide, which we breathe out. But you knew that.

What happens next is a little weird and a little hard to describe, so you'll have to bear with me. All that hydrogen that the vitamins picked up is whisked away to something called the electron transport system, which is also in the mitochondria. This is a four-stage process facilitated by--guess what--more vitamins! (Seriously, take them.) The first three parts are full of things called Coenzyme Q and Cytochrome C, which doesn't sound arbitrary at all (it totally is), but at the end of the chain is oxygen. Remember from all that antioxidant talk how greedy oxygen is? That makes it an excellent magnet to stick at the end of this electron transport system. It draws that hydrogen all the way through this little system, and the hydrogen gives up a little more of that photosynthesis energy in each stage. By the time it gets to the oxygen, it's totally depleted and perfectly content to shut up and make water. All that energy goes out into the universe that is our body, and we can use it to do important things, like eating more tempura. Mmm, tempura.

Honestly, this was a tough concept for me to grasp, because it's totally invisible and a little metaphysical and full of concepts that aren't in my area of expertise. I'm hoping that by the time I'm a big, grown-up scientist, I'll be better able to grasp the concept of energy being a tangible product that we can consume, manipulate and produce. Maybe that's more of a physics thing. I was never very good at physics.

Anyway, be good to your body. It does a lot of really cool stuff without even thinking about it. (If I had to think about cellular respiration a persquillion times a day, my brain would explode.) And take your vitamins. Just not too many. That's bad.

Squooshy ...

I promise there'll be a proper blog post when it's actually daytime and I have energy, but for now I'm still coming down from my well-wasn't-that-neat post-lab high. The experiment we did today was about osmosis, which I'll get to at some point, and it involved plain old chicken eggs.

If you've never done this, try soaking a regular egg in vinegar for a few nights. The hard outer shell slowly dissolves, leaving that clear membrane that you usually have to tear off when you're peeling a hard-boiled egg. It's tougher than you'd think, and you're left with a transparent goo-ball of an egg! You can see the yolk bobbling around in there and everything.

Yeah, not very sciencey compared to my usual fare, but it's something to do if you're really bored. Or with your kid or something. I bet kids would love this (or at least be entertained by it for a few minutes).

From Asteroids to Organelles

Cells. We have a heck of a lot of them. A quick Google search indicates that there's some discrepancy as to exactly how many we have, but the consensus is up in the high trillions. And a trillion is an awfully big number, you know.

But what goes on inside them? To ponder that, we have to think on a much tinier scale than what we're used to. One of my favourite authors, Madeleine L'Engle, is excellent at doing just that. If you haven't already, I highly recommend reading A Wrinkle in Time and its sequel, A Wind in the Door. Not only are they both excellent books, they also force you to really think about our position in the universe and our composition as human beings. A Wrinkle in Time sets humans up as microscopic yet integral fibres in the grand tapestry of all existence, human and otherwise. And, as if you needed your worldview (universe-view?) broadened any further (and of course you do!), A Wind in the Door then proceeds to demonstrate that we're not complete units of existence ourselves. The climatic events of the story take place inside one mitochondrion, which is a tiny functional unit within one cell. Nothing has made me feel simultaneously so small and so enormously powerful like these two books, and I can't wait to finish the whole series.

So. What does Madeleine L'Engle have to do with biology at the cellular level? Well, she beautifully illustrates the fact that the state of being human is actually an amalgamation of trillions upon trillions of highly complex functions going on all the time in our body. These functions are extremely specialized. If just one minute process is not carried out exactly as it's supposed to be, we're screwed. Ignoring the universe for a second, let's think of the human body itself as a tapestry. If just one thread goes awry, suddenly our heraldic lion loses its fangs and isn't so tough anymore. And that's just embarrassing.

To keep our body running, we rely on a complex system of organs. We've all (hopefully) got our hearts, brains, lungs and livers. Each of our organs performs a very specific function essential to life. Just like the human body as a whole, each of our cells has organs too. We call those organelles--adorable mini-organs that are specialized in a similar way. Thanks to incredible advances in microscopy, we're able to see organelles up close and personal, which tends to really skew my thinking if I'm not careful. More than once (yes, I'm a nerd) I've caught myself looking at an electron microscope image of, say, a Golgi apparatus and thinking it must be some kind of folded-up tissue. Nope! The Golgi apparatus is an organelle, completely invisible to the naked eye. 

I promise I'll explain what the Golgi apparatus actually does in a later blog post. It's just one of my favourite organelles to bring up because it makes me feel so smart every time I say it. Golgi apparatus. Golgi apparatus. Golgi apparatus. Try it at home (the second 'g' is soft).

While cells may look like they should be able to function on their own--after all, they've got their own organ(elle)s and everything--they can't. Not our cells, at least. If you don't weave the tapestry together, you've just got a tangled pile of thread. Your cat might like it, but it sure doesn't do us much good. Cells rely on each other to keep doing what they're doing, whatever that happens to be. Everything a cell does relies on specific chemical reactions, and the chemicals that they use have to come from the cells that produce them. Intercellular communication and cooperation is the key to life. Get enough cells together and in the right cooperative formation, and you've got an organ. A bone. A body.

I am going to explore organelles in greater detail later, but for now I just want to impress upon you, my dear reader, how incredibly awesome it is that we are so small in the face of the universe while essentially being a universe to the smallest known unit of life. How many components can the human existence be broken down to? Where does the body end and our environment begin? How far can we go in defining the human body before we are met by things we can't define? For me, these are questions not only of biology but of spirituality as well, and the more I learn, the more I believe that the two are inextricably linked in the story of our bodies, our universe, and beyond.

Radical!

For years I saw the term 'free radical' bandied about in all sorts of magazines and newspaper articles without having the faintest clue what it actually meant. All I gathered was that they're bad. And they are! (Sometimes.) Here's a quick primer on what they do.

Free radicals are invariably oxygen compounds. The most important thing to understand is that oxygen is a bit of a drama queen. Oxygen is especially attractive to other atoms, and it will do its darnedest to hook itself onto just about anything to form a chemical bond. Why? Well, that's just how it rolls. In fact, unpaired oxygen is so hungry for chemical companionship that it will go so far as to rip away atoms from other molecules. It's the pretty, popular girl who stole your prom date away for half the night, leaving your teenage heart devastated.

Except emotional anguish is nothing compared to what ripping apart a molecule can do to the body. When a free radical attacks a cell, it takes what it wants and leaves the rest of it wondering what the hell happened. Among other things, it destroys the DNA within the nucleus of that cell, meaning it can't just fix itself. The cell is screwed. There's not much it can do now besides keel over and die.

This has its practical applications. Hydrogen peroxide works as an antibacterial agent because of its greedy oxygen component. It's essentially water with an extra oxygen atom, so that extra atom is more than happy to latch on to bacterial cells, ripping them apart and destroying them. It's awfully handy. Free radicals are also present in many of our own biological processes, responsible for breaking down things that actually need breaking down, like waste materials and foreign invaders. We need a decent amount of them to live.

But the bad, evil, scary kind of free radicals that all the magazines talk about are the ones responsible for aging. Over a lifetime of exposure to free radicals, the cells in our body break gradually break down with no hope of repair or replenishment. Fashion mags hate free radicals because they're what makes our skin wrinkle and sag as we get older: they break down skin cells, leaving gaps in our once taut and radiant faces and making the skin more elastic. Health mags hate free radicals because their interaction with cellular DNA can create malignant tumours and other nasty problems. 

Like everything else in our body, balance is key when it comes to free radicals. Too few, and essential tasks don't get done; too many, and we get horrible, horrible diseases. So how do we regulate something that sounds so sketchy? The answer is in antioxidants, another thing we read about all the time without necessarily understanding what it means. To get a rough idea of what they're actually doing, let's go back to the prom metaphor. If a free radical is the mean popular girl determined to ruin the most important night of your life, then an antioxidant is like an intercepting popular dude who sweeps her off her feet before she can sink her talons into your date. (Or another popular girl. God forbid the queer science geek turn heterocentric on her own blog.) Antioxidants are nothing more than molecules willing to be free-radicated themselves, protecting cells in the process. 

Okay, so the correct term is oxidized, not free-radicated. But I like mine better.

(As a mildly interesting side note, and because I know my dad is reading this, I feel compelled to mention that one of my first science fair experiments as a kid was about oxidization. My dad and I put all kinds of crap on sliced apples to see what kept them from browning. And why do apples brown? Because oxygen atoms in the air act as free radicals and destroy the apple cells from the outside in, killing it slowly and painfully. I didn't quite get that far in my thinking in Grade 5, despite Dad's best efforts, but now I think I get it.)

Humans don't naturally produce all the antioxidants we need, so we have to add them to our diets. And that's where vitamins come in. Vitamins C and E are especially good antioxidants, and they're found mostly in fresh fruits and vegetables (or candy-flavoured tablets, if you really can't stand spinach). There are also great chemical compounds in things like tea, coffee, soy, red wine and chocolate that act as antioxidants, which is why you have all these smug bastards gloating about how their doctors told them to drink a glass of wine every day and eat more (dark!) chocolate. You might want to focus more on the vegetable side of things, though, unless you've been really dying to break in your copy of Wii Fit.

So, free radicals: good, bad, and totally destructive, like a sexy prom queen on a monster truck. And you'd better believe that's what I'm writing on my midterm.

Evolution: it works!

So evolution is really important. Whether you want to believe it or not, all living things are evolving all the time. If they didn't, they wouldn't be here today. When most people think about evolution, they think about apes turning into humans or, if they're really nerdy, dinosaurs turning into birds. And while that's cool and all, there are examples of evolution all around us that happen in short enough spurts that we can see them (and their consequences) within our measly human lifespan. 

The first thing to get past, though is this idea of nature vs. nurture. I see this idea come up a lot when people talk about evolution and biodiversity and whatnot. The truth is, the influences of nature and nurture are split pretty evenly. For example, you can have two tall parents, but if your environment restricts your access to proper nutrients, you probably won't end up looking like an NBA player. Nature (your genes) and nurture (your environment) need to work together in order for any genetic predisposition to come out. 

Where you really should be thinking about nature and nurture is when it comes to natural selection. Evolution happens within a population of living things when that population's environment changes. As long as the change isn't something totally devastating, like--oh, I don't know, an asteroid or something--then the population as a whole will adapt genetically to it. If an area gets, say, colder, then organisms with traits that protect them from cold will be more likely to survive and thus pass those genes on to future generations. After some time, you'll have a shiny new population of tulips or caribou or whatever that has evolved to better withstand cold.

But it's important to remember that evolution is not predictive. It can only work with what's already there. A great example that my professor brought up in one of our first classes is the human spine. Our backs kind of suck. That's why there's a thriving industry dedicated to alleviating back pain. We have chiropractors, we have special painkillers, we have those pathetic commercials with the miserable-looking wooden puppets. And why do our backs suck? Because they're meant for quadrupeds, not bipeds. Throughout the course of human evolution, it became advantageous for us to walk on two legs instead of four. It's awfully convenient, isn't it? But our backs have no way to catch up. We have a mutated quadruped spine, and that's the best our genes can do unless we go out and mate with--I don't know, T-rexes? No magic bipedal gene has or ever will pop up in our species that will give us a better spine design, and people with especially crappy backs can still reproduce and pass on their crappy-back genes. Chiropractors, rejoice. 

So that's a long-term example. But what about that short-term, within-our-measly-human-lifespan business? Well, for a great example of that, let's look to Australia. Australia has a bunny problem. (Not a terrible problem to have, but then again, I'm not a farmer. I just really like bunnies.) Scientists have tried again and again to introduce a variety of specialized bunny plagues in the hopes of reducing the population. And it works--sort of. But in the long run, it causes more problems than it solves. Why is that? Well, inevitably, you'll have some bunnies that just so happen to be naturally resistant to the plague of the week. While the other bunnies are busy dying painfully, the plague-resistant bunnies continue to mate and reproduce as usual. Before you know it, you've got a fully restocked continent of bunnies that are immune to your fancy plague, because now that's a genetic trait advantageous to survival. 

That's an awful lot of words I just typed up there. In a nutshell, evolution is the change over time in a population of living things as helpful genetic traits are passed on. Without it, life on Earth would not be able to cope with our ever-changing environment. And then we'd all be dead. And that would suck. For those of a religious persuasion who are hesitant to accept the theory of evolution, why not think of it this way: isn't your God smart enough to come up with something like this? It's efficient and (mostly--pandas, I'm looking at you!) effective.

Evolution: the ultimate time-saver!

Just what do I think I'm doing?

After all, I have no credentials, no expertise, not even a lab coat to my name. (Which is a damn shame. I love lab coats.) I'm a first-year college student taking the most basic, remedial biology class I could find. I didn't do all that well in high school, and my academic and professional focus to date has been purely on the arts.

So, what do I have?

Passion. I think biology is one of the most incredible disciplines out there. It is the cornerstone of our existence. It is what helps us understand not only the world at large but also the invisible, everyday processes that determine each millisecond whether we live or die. It takes us from the ocean floor to the highest mountain peaks and beyond. It is, in a word, fascinating.

Through this blog, I hope to document my experiences as I learn absolutely everything I can about the living world. Stay awhile and learn with me. If I've got something wrong and you really feel the need to correct me, please feel free to do so in a kind and respectful manner--after all, I'm only a first-year! No matter your level of experience, knowledge or interest, keep just one thing in mind: in the immortal words of Bill Nye, "Science rules!"