Nonsynonymous mutations, on the other hand, alter the amino acid sequence of the protein and in many cases are detrimental to the fitness of the organism, so most of these mutations are eliminated by natural selection.

TLS Online TPP Program

#Id: 8951

#Section 3: Genetics, Cellular and Molecular Biology

TLS Online TPP Program

#Id: 2229

#Section 3: Genetics, Cellular and Molecular Biology

The Birth of a Gene - Duplication is the most common way that new genes arise in eukaryotes. 

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#Id: 8952

#Section 3: Genetics, Cellular and Molecular Biology

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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#Id: 8953

#Section 3: Genetics, Cellular and Molecular Biology

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.

TLS Online TPP Program

#Id: 8954

#Section 3: Genetics, Cellular and Molecular Biology

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.

TLS Online TPP Program

#Id: 8955

#Section 3: Genetics, Cellular and Molecular Biology