May 28, 2010


Without naming any names, this man I know who brews his own beer would like to see a blog post about what the deal is with yeast.

Here are the basics:
Yeasts are a type of fungus.  Most fungi are multicellular, like mushrooms, but yeasts are unicellular (or single-celled, whichever you want to say is fine).
Don't confuse yeasts with bacteria.  I know they both are single-celled, but that's pretty much all they have in common.  Yeasts have a nucleus and organelles, and bacteria don't. Also, yeasts are around 50 times bigger than bacteria.
Yeasts are known for a few things, but I'm going to focus on one in particular: their role in producing alcoholic beverages.
When yeasts have oxygen around, they behave much the way that our cells do.  They bring in sugar and break it down to get energy and release CO2.  For reasons I won't get into, this process is most efficient when oxygen is around (it has to do with oxygen accepting electrons--see? Did you really want to know that?)

BUT, when there isn't any oxygen around, the system makes a switch and the process creates ethanol (a type of alcohol) as a side product.
Here is the human equivalent:  When your muscle cells have a good supply of oxygen from your blood, they can get a lot of energy, and in turn, do great things for you when you are exercising.  But if these cells don't get enough oxygen (because you're out of shape and your lungs and heart aren't up to the task), they'll still do what they have to do, but they will switch gears and work without oxygen.  This will produce lactic acid (instead of alcohol because, well, we're not yeast) as a waste product, which is what causes muscle cramps.  
So the process of creating beer or wine (or whatever other alcoholic concoction you want) takes advantage of yeasts' abilities.  Beer brewers mix a variety of grains and spices and add a certain variety of yeast (there are hundreds), and the yeast eats all the lovely sugars in the mix and release CO2 (carbonation) and ethanol (alcohol).  This whole process is called fermentation, and beer brewers get all starry-eyed when you mention it.  They may also drool.
A big part of beer brewing involves keeping the yeast happy.  You want them to ferment at the right temperature, with the right amount of sugar, and without any unwanted guests.  It's important that the beer mixture not be infiltrated by unwanted bacteria, which can ruin the taste of the beer, and generally annoy the yeast that has a job to do.

Beer brewers go to great lengths to keep yeast happy because they so appreciate what yeast do, but sometimes I really feel like the yeast are taking advantage.  Just a feeling.

Artificial Life

Don't freak out. Don't freak out. Don't freak out.

Okay, scientists have created something.  Something artificial.  This is real, people.

Okay, no.  That wasn't real.  That was a trailer for Splice.

Here is what is really going on:

You can click that picture to see the full article, but if you're lazy or if your mouse or finger or both is/are broken, I'll just explain what is going on.
These scientists took all the DNA out of a bacterial cell, so they had a blank life slate.  Then they placed home-made DNA into the empty bacterial cell, and voila! Synthetic life.  So, the whole thing isn't artificial; it's considered "artificial life" because the DNA they added was a sequence that the scientists made up. (Scientists love doing that.)
They didn't even assemble all the DNA themselves (how lazy!).  They just injected the cell with a bunch of pieces of DNA that they had assembled in the lab, and the pieces joined together to become the bacterium's chromosome.

To put this in terms of the human body, it would be like removing someone's brain and replacing it with a brain someone made in a lab. (Wow, I'm really failing at making this sound not scary.)

This would be weird if it wasn't just an extra step in a process we've been doing for years.  Bacteria love incorporating foreign DNA into their own DNA.  They live for it.  If two bacteria are next to each other, one can "pass" some DNA to the other.  This is how bacteria can become resistant to antibiotics so fast.  If one bacterium finds a gene that makes it immune to the drug, he/she/it just says "Hey, everyone.  I've found the solution.  Come and get it!" And he can distribute the gene to everyone. Cool for them.  Not cool for us if they happen to be in our sinuses when they're doing this.

But we humans can taken advantage of bacteria's love for accepting random DNA.  For example, it's a great way to mass produce insulin for diabetics.  We took the gene that has instructions for making insulin from a human cell and just gave it to some bacteria, who said, "Hey thanks, a new gene for me to use.  I've been looking everywhere for one of these!"

So basically, bacteria are cooperative little friends that make great toys for scientists.  I'll admit that the scientists' timing isn't the best--creating "artificial life" so close to the release of Splice.  But I suppose they didn't consult imdb when they planned their research proposals.  Obvious oversight.  But if manipulating bacterial chromosomes is "playing God," we've been God for decades.  So I wouldn't really worry about scientists creating angry cross-eyed superhuman mutants.  That probably won't happen for at least 5 more years.  Sweet dreams!

May 11, 2010

Evolution of Fashion vs. Evolution of Life

Everything changes over time.  Life, fashion, and language are pretty good examples (dost thou agree, dear sir?).   Now I present to you an extended comparison of fashion and evolution:

May 07, 2010

Hairy Oil Spill

I've donated hair to Locks of Love twice--almost 3 feet of hair total.  Until today, I thought that was the highest purpose for my hair trimmings, but it turns out you can also rescue baby seals with your lovelocks.  I'm definitely making sure my salon sends their hairballs to this nonprofit, Matter of Trust.

I had no idea the protein mass spewing out of my skull had so many uses once it's detached from me.  Next they'll tell me that hair can replace cotton... and can openers... and plastic bags.  I'm waiting.

I got a haircut and found out that my hair stylist (who also owns the salon) was way ahead of me, and does indeed send hair trimmings to Matter of Trust.  Bravo, Bravo!

May 03, 2010

Giraffes and Red-Nosed Reindeer

I already got a question about the previous post:  "If giraffes don't have long necks because of generations of giraffes stretching their necks, how did they get so long?"  In other words, "If you can't give acquired traits to your children, how do species get so well suited to their environment?"

Let's stick with the giraffes:
(By the way, doesn't it sound like the plural of giraffe should be giravves? Like half and halves? Hm.)

Giraffes evolved from a deer-looking ancestor with an average neck length.
A few random mutations in a group of them brought about a few individuals with longer necks.  These long-neckies could reach leaves on trees that no one else could reach, so they never went hungry.  They had long-necked children, and so on and so on until we get very long-necked giraffes (or giravves, if you're with me on this one).

I'd like to imagine that the first of the really tall giraffes was mocked much like Rudolph--perhaps they never let him play in any giraffe games.
But then when all the other giraffes saw that his long neck made him able to reach all the yummiest of the leaves up high on trees, they shut up about it--the same way that Rudolph's red nose mutation turned out to have a great purpose as well.
In fact, that's really how evolution works.  It's not that species come up with traits that would serve them well, it's that species find uses for the bizarre traits they have.

So when I say that a species can't pass on inherited traits, it's another way of saying that a species can't choose to change or not change.  It's not deliberate.  You can't control it.  Evolution doesn't care about what giraffes want.
But giraffes can certainly make the best of it.