EHJ352H1 Lecture Notes - Lecture 6: Codon Usage Bias, Intellectual Disability, Epistasis
26 Jan 2013
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Document Summary
Human chromosome 2 resulted from a fusion of two ancestral chromosomes that remained separate in the chimp lineage. Human-chimp differ by at least 9 pericentric inversions. Single nucleotide substitutions occur at a rate of 1. 23% between copies of human and chimp genome. Fixed divergence is estimated to be less than 1. 06% Within-species polymorphism where 2 different copies of the human genome (or 2 copies of the chimp genome) will not be identical. To estimate the true difference between humans and chimps, we must account for diversity within each species. There are many fewer indel differences than nucleotide differences: 10 million. Most are small (45% cover one bp, 96% < 20 bp) but the largest few contain the most sequence. Largest 1. 5% of indels contain around 73% of affected bps. These indels result in each species containing 45 mb of species-specific euchromatic sequence. This causes around 3% of difference in sequence that is much larger than the 1% nucleotide divergence.
