How do the three key biological ideas of cells, genes and natural selection link together?
Sir Paul Nurse: I want to relate the idea of natural selection to the two previous ideas of the cell and the gene. Because, in fact, what he know about cells and what we know about genes means that they must automatically undergo evolution by natural selection.
What we see [in the picture] is a cell undergoing division from one to two. There is a single chromosome, and that is the blue sort of wiggly line up there. And that chromosome determines the properties of the cell. When the cell divides, it copies the chromosome. The new chromosome seen in the two newly divided cells determines the properties of the two newly formed cells. Now, because some variability occurs when the DNA molecule that makes up the chromosome is copied, and you can also get some genetic damage, what that means is that cells that have produced will have variability in their hereditary material. So these cells reproduce. They have genes as a hereditary system on chromosomes. And when copied, you can mistakes, or get variability, which provides the material upon which natural selection can work.
The two ideas encapsulated in this figure are the ideas of the cell, and the ideas of the gene, and from that you can conclude that evolution by natural selection can occur. These three ideas are very closely linked as important ideas in biology.
