June 22, 2010

Chromosomes

Chromosome!  Does that word scare you?  Let's tone it down a bit.  From now on, instead of saying chromosome, I shall say chromie-somie.  It's more fun to say, it is more fun to type, and it involves a hyphen.  These are all excellent qualities.
A chromie-somie look like a mildly overweight X.
Chromie-somies are the way DNA is packaged in the cell when it's not being used.  It's like a clothes dresser.  When you are not using your clothes,  you fold them and place them ever so gingerly in a drawer (theoretically, that is).  By folding and storing them so, you are keeping them safe from damage and unnecessary wear.
You open the drawer and select a specific article only when you need it.  You wear it, and then when you're done, it goes back in the drawer (after washing it, if you are really on top of things).  If you just leave your clothes anywhere and everywhere, your clothes will get wrinkled, dirty, and frayed.

The many possible fates of clothes left to fend for themselves on the floor:


In this analogy, the bureau is the genome, the drawer is a chromosome--I mean, chromie-somie, and the articles of clothing are individual genes.  The act of selecting a shirt from the drawer is the way a cell unwinds the DNA to get to a specific gene, and then puts the DNA away again.
Now for structure: chromie-somies are DNA that is wrapped around proteins called histones, which are then stacked on top of each other like balls of yarn.  Again, it's all about protecting the DNA from damage.  You want to store is neatly and compactly.
We human beings (for I assume no walruses read this blog), have 23 pairs of chromosomes, for a grand whopping total of 46.  You have pairs of chromosomes because you get a set of 23 chromosomes from each parent.
For every single gene in the human genome, you have 2 copies.  It's a great system because if you get a "broken" gene from 1 parent, you still have a chance of getting a "working" gene from the other parent.  Nature hedges her bets.  She's so smart.

June 15, 2010

DNA, Genes, Genomes... and Hamsters

Just kidding about the hamsters.

Every living thing on earth has DNA (though I make no such promises about aliens).
Think of a DNA as a manual with instructions for building and maintaining an organism.  
The whole manual, then, is the genome: all the DNA for a particular organism. 

If the genome is a book, then each page is a gene, which has instructions for making a specific protein.  
These proteins are what make you who you are and every other living thing what he/she/it is.  It's all about the proteins.  They are the pigments that determine your hair, skin, and eye color (which I hear is a big part of our identities).  They are the hormones that make you a man or woman.  They are the neurochemicals in your brain that allow you to think.  Proteins in certain concentrations in certain areas during development proclaim "arm goes here" and "head goes here."
I'm not entirely kidding.  Proteins look a lot like this.
Every cell has the full set of instructions, but not every cell reads the whole manual.  It's split into chapters.  The cells in your liver just read the "liver cell" chapter, while those in your heart just read the "cardiac muscle chapter."  

As cells consult the manual every time they need to build a new protein, you'll get some wear and tear.  Sticking with this book metaphor we have going here--you can tell the difference between a brand new book from Barnes&Noble and a book that has been read 100 times at the beach, at a diner, and in the bath tub.
*Both are Mary Roach books.*   
*Also, I swear I don't treat my books this way.*
This wear and tear on the genome is what causes aging and sometimes cancer.  If you spill some ketchup on the page that describes how to make the protein melanin, you'll start to get grey hairs because your hair follicle cells can't read the exact instructions any more.

Our human manual is not entirely unique: 98% of the pages in our manual are also in chimpanzees' manual.  The more similar two creatures are, the more pages they have in common.  We share many of our pages with other vertebrates, like lions, tigers, and bears, but we also share half our pages with bananas, so don't get too cocky.




June 11, 2010

Interconnectedness

On my drive to work today, NPR told me (just me--no one else) that Japan is in serious financial trouble.  I believe they compared themselves to Greece.
I thought about how all the financial troubles in the international community underscore the interconnectedness and smallness of the world.
For the record, I do realize that I should probably wait until I park to think about things like this.
And being the biology nerd that I am, I thought about how this theme applies to the natural world as well.
Life is connected through time and space.  By time, I mean that you only exist in this moment because in the last 3.8 billion years, no ancestor of yours died before reproducing.
Every twist and turn in life's history has lead to this moment.  Every success, every tragedy, every story played its part.  For instance, if a giant asteroid hadn't hit earth and caused a worldwide mass extinction 65 million years ago, dinosaurs would probably still rule the earth, and we wouldn't exist.  I like the story of the time traveler who steps on a dragon fly millions of years ago and disturbs the whole space-time continuum.  What was that?  A twilight zone episode?  Google says it's Stargate, but surely that's a retelling of the old story.  Have some fun asking Google about time traveling mistakes.  Here, I'll do it for you.
Life's interconnectedness in space is the study of ecology--organisms' interactions on various scales.  A grasshopper eating grass is an interaction, and a lizard eating the grasshopper is another interaction.  It's not just about who eats who, though.  Earthworms' processing of dirt and making it suitable for plants to take root is another interaction.
So this brings me back to Japan's economic crisis: ecology and economics have a lot in common.  An ecosystem is only stable, and therefore successful, if it has a high degree of diversity.  Everything functions better with variety.  Ecosystems build stability from the bottom up, and they can't be too top heavy: you don't want to have more predators than prey because you can't have all the energy trapped in the highest level of the ecosystem.  It has to be spread around for the ecosystem to flourish--the same way the economy can't function if 99% of the country's money is in one man's savings account.
Ecosystems and economies function best when energy and money is exchanged freely and often in a variety of ways.  Also, no part of the chain can consider itself separate from the others.  An eagle may be at the top of the food chain, but being at the top just means you are dependent on everything below you, so you have some serious incentive to keep the food chain functioning.

I could go on and on about how variety is better for everything (diet, wardrobe, genetics, throw pillows, race) and how much evidence there is for the interconnectedness of all things (religion, weather, overfishing, movie remakes, non-native species, pollution, language), but I won't do this to you.  This post is already too long.

Interconnectedness means our mistakes have ripple effects, yes, but it also means that we are all in this together.  "This" being existence and prosperity.  The togetherness spans all barriers--race, religion, nationality, species.  Our planet is a global community of countries, peoples, and ecosystems.  The more we realize this, the more we will help each other, and in turn help ourselves.  Group hug!
(Did I just make you vomit?)

June 08, 2010

Earth is Old

The video below is just an experiment.  I'd like to start doing some flash animations, but flash and I are still getting acquainted (we're on our second date).  In the meantime, I wanted to see what I could do with a pencil, a scanner, and imovie.  Again, just a test.  Keep the expectations low, please.  I'm fragile.





June 03, 2010

Non-Native Species

We humans have this nasty habit of thinking we know everything.  (In my case it's true, though. I do know everything.)  Sometimes we can only learn the truth--that we really don't have a clue--the hard way.  We know especially little about how large ecosystems function, and nothing makes this more obvious than introducing non-native species.

People seem to think that toying with an ecosystem is like cooking.



I'm not entirely making this up.  This stuff happens.

This can and mostly likely will spiral further out of control...

Okay, I did make this part up.  But still... the point is that messing around with ecosystems can quickly become dangerous and, as you can see, really ridiculous.

When I think of non-native species I usually think of animals, but the problems are just as severe with plants, if not worse.  A fantastic example is Kudzu (sounds like the plant's rapper name, no?).


This ambitious vine was introduced into the southern areas of the United States in the 1800s because of claims that its strong roots were good for controlling erosion.  Kudzu, which is originally from Asia, turns out to absolutely adore the climate in the South.  It can grow up to 1 foot per day while it chokes the area's native plants.  And because it's from out of town, it has no natural pests or predators that can keep it in check.  It just grows... and grows... and grows.
There's no way to get rid of it, save for detonating an atomic bomb in the area.  Seriously, what are you going to do?  Trim it? It can grow a foot per day.  Are you going to spread 7 million acres (that's how much it monopolizes) with caustic chemicals?  I don't think so.

Part of what makes us human is testing our limits and exploring our surroundings.  That's great. But we really have to quit thinking that ecosystems are made of play-doh.  They're not toys; you can't play with them.  You can't shape them into something else.  Ecosystems are more like porcelain. Don't touch! You'll break it, and they don't make super glue that works on the ecosystem level yet.

If you want to continue to nerd out (and I know you want to), you can check out the U.S. list of non-native species: invasivespeciesinfo.gov  You're welcome!