Monday, April 29, 2013

The actual reasons behind sickle-cell anemia

It's week 8 of my MIT Biology course delivered online via, with the lectures by the highly-esteemed Eric S. Lander, director of the Broad Institute, a man largely involved in the recent Human Genome Project.

During weeks 6 and 7, there was a bunch of really cool things.

We had a long discussion (a few lectures) about hemoglobin, the protein that carries oxygen from the lungs and throughout the body. Well, the only protien worth mentioning under normal circumstances.
Most everyone knows that sickle-cell anemia is caused by defetive hemoglobin, which is sickle-shaped rather than the normal cell shape. But why is it defective? How? And what makes the sickle shape and why?

It turns out the answer is in the molecular biology of the human genome. The lecture explains what particular error makes the gene (that makes hemoglobin) defective, and how that error might occur. It then explains the molecular results of the error, which are simply a misalignment of negative charges. Those negative charges result in a string of hemoglobin proteins, which crystallizes into a rod which then shapes the sickle cell. Thus the visible shape of the diseased cells is a consequence, not a cause, of the disease.

Anyone with anemia should really get to watch these lectures. I really hate that the videos might not be readiy available online.

Another really cool thing I learned was why some viruses are especially awful and hard to get rid of, like HIV. These are called retroviruses, and as I understand it insert their destructive genetic material into the genetic code of the host, becoming an integral part of the cell and pretty much impossible to excise.

And then the lectures go on to explain things I had not learned in high school, but thought I had. I thought it was impossible to have a offspring have a phenotype unknown in their ancestry. Right after high school, I went so far as to explain to a Chinese friend that first generation Chinese children could never have blue eyes because there were no blue eyed genes in the Chinese parents (or even in a marriage between a Chinese and a blue-eyed Caucasian).

Turns out, its not as simple as I had been taught. Yes, what I had been taught was a good foundation, but it didn't address all sorts of genetic hanky-panky that can go on, such as recombinant DND and transposons.

After all this, there was yet more. I was especially intrigued by the "computer logic" of DNA and proteins. Many genetic sequences are like "switches" that turn on or off a specific gene under specific circumstances.

I gotta go watch another lecture.
Jolan tru.

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