Mutations that remove the 2’-OH of the A residue at the 30 end of the P-site tRNA result in a 106-fold reduction in catalysis rates. This “substrate-assisted catalysis”

2’-OH of the P-site tRNA may act as part of a “proton shuttle”

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#Unit 11. Evolution and Behavior

One is unequal crossing over, in which recombination happens between different positions on chromosomes that are misaligned during meiosis. 

Another is replication slippage, in which the DNA polymerase loses its place and copies a segment of chromosome twice.

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#Unit 11. Evolution and Behavior

A third way that gene duplicates arise is by retrotransposition.

Here the messenger RNA from a gene is reverse-transcribed to DNA, which is then integrated into the genome.

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#Unit 11. Evolution and Behavior

As a chromosome with a new gene duplicate spreads through a population, there is polymorphism in the number of copies of the gene that individuals carry. This situation, called copy number variation.

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#Unit 11. Evolution and Behavior

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#Unit 11. Evolution and Behavior

Mixtures of exons duplicated from genes with different functions can generate new genes with new functions, a process that is called exon shuffling.

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#Unit 11. Evolution and Behavior

Gene duplication happens on a massive scale when whole genome duplication occur. whole genome duplication are two type, 

1.Autopolyploid

2.Allopolyploid