Re: Does Evolution "Knock Out" Genes?


"g" <gillawton@xxxxxxxxxxxxx> wrote
What exactly are you meaning to say here? That biologists have taken an
existing adult animal and removed from every cell a certain coding
sequence?
Or, are you meaning that biologists have removed a given sequence from a
sperm and an egg and then fertilized the altered egg with the altered
sperm?
Or what? Your message is too vague to attach any meaning to.

A "knock-out" is basically the second.
You have to fuse the altered cell with another embryo to create a chimera,
and then inbreed to finally knock out the gene of interest. You can buy
"knock-out" mice with any gene deleted. Some never get past the embryo
stage, but most are viable, and most, as the OP said, don't seem very much
the worse for wear.

The question is, if the genes are not essential, why aren't they lost in
evolution? Some genes are lost, for instance most mammals can synthesise
vitamin C, but primates can't.

The answer is probaby that the cost of keeping a gene is quite low, and even
a very slight selective pressure can maintain it in the population, if the
mutation rate is also low.

III. If you want to know what really is going on in science, the best
source of information is from the people who honestly and dedicatedly are
doing the work at the cutting edge. You might have to burn a little
midnight oil to get your science fundamentals up to where you can grasp a
little of it; and that takes work.

The best source of information is first-year undergraduate textbooks. In
biology they are usually easy enough to read, and they are written by
responsible and serious people. They are also up to date within a few
months.
The problem is they tend to be rather expensive.



.

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