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Dinesh

Dinesh club

Posted: 26 Nov 2023

Taken: 26 Nov 2023

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Page-77 •
Evolution •
A Triumph of an Idea •
Author •
Carl Zimmer •

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Cells build proteins in a three-step process. First, the cell copies its double standard DNA into a single-strand version called RNA. Then it ships the RNA to a protein-building factory called a ribosome. There, in the final step, the RNA acts as a template for the ribosome as it builds a string of amino acids, creating a protein

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 Dinesh
Dinesh club
. . . Cells can duplicate their DNA almost flawlessly, but every now and then a mistake creeps in. Proofreading proteins can find most of these mistakes and fix them, but a few slip through. Some of these rare changes – known as mutations – may alter a single letter in the recipe of the DNA, but others can be far more drastic. Many pieces of DNA can spontaneously cut themselves out of one position and splice themselves back in elsewhere, altering the gene where they make their new home. Sometimes when DNA is being copies as a cell divides, an entire gene an get duplicated, or even an entire set of genes.

When DNA mutates, a cell may simply malfunction and die, or it may multiply madly into a tumor. In either case, the mutation disappears when the organism that carries it dies. But the mutation happens to alter the DNA in a egg or a sperm, it gets a chance at immortality. It may get carried into the genes of an offspring, and that offspring’s offspring. . . . .

But sometimes instead of harm, a mutation does some good. It may change the structure of proteins, making them more efficient at digesting food or breaking down poisons. If a mutation’s effects allow an organism to have more offspring, on average, than the organism that lack it, it will gradually become more common in the population. As the mutant’s offspring thrive, the mutation they carry become more common, and it may do so well that it drives the older version of the gene to extinct. Natural selection Fisher and Wright showed, was largely a matter of changing fortunes of different forms of genes. ~ Page 77/78
11 months ago. Edited 11 months ago.
 Dinesh
Dinesh club
As Stringer started at fossil skulls, a geneticist at the University of California at Berkeley named Allan Wilson was trying to reconstruct human history with biochemistry. He set out to analyze the DNA in human mitochondria – those energy generating factories of the cell that carry their own DNA The chose mitochondria DNA rather than any of the genes in the nucleus because it passes from one generation to the next relatively unchanged. Unlike most genes, which are stuffed between the chromosome we inherit from both our parents, mitochondrial gene come only from our mother. Any differences between a mother’s mitochondrial DNA and her child’s can arise only when the genes spontaneously mutate. . . . . ~ 298

Evolution - THE TRIUMPH OF AN IDEA
11 months ago. Edited 8 weeks ago.

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