The hardest chapter up till now has been this one. The other two are a simple introduction to the huge and difficult world of genetics. There are many important terms mentioned for the first time in chapter three and it is very important to define them. There is also a more complete definition for the word gene that I think is very important to write down.
Dawkins changes the metaphor he has been using. Pages no longer fulfills to represent the gene because it starts to break down. Therefore he uses a ticker tape.
The immortal coil is the DNA. "It consists of a pair of nucleotide chains twisted twisted together in an elegant spiral" (page 22). There are four types of nucleotides and every living thing has them in a different sequence. Human beings have 46 chromosomes divided into 23 pairs. One of the mother and one of the father.
A gene can be recessive when it is ignored and dominant. Two genes that are rivals are known as alleles.
Mitosis takes place when a cell divides into two. Meiosis is different because it only occurs in the sex cells and it only contains 23 chromosomes.
A cistron encodes the information of when to start and when to stop.
Genetic unit is "a length of chromosome"(page 29). The smaller it is, the more probable it is that you share it with someone else.
"A point mutation is an error corresponding to a single misprinted letter in a book" (page 31).
Inversion is another form of mutation that occurs when a piece of chromosome detaches rotates and reattaches.
Therefore Dawkins states that the gene is the basic unit because it has longevity, fecundity, copying fidelity,and it is almost indivisible. He the goes back to his original topic of selfishness and altruism and says that altruism is a bad characteristic and that genes are the first to be selfish.
Sexual reproduction vs. non-sexual reproduction....Evolution.
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