Biology 1002B Lecture Notes - Lecture 22: Neurotransmission, Olfaction, Hoatzin
28 Nov 2015
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Sequence conservation high homology nucleotides are conserved in both strands. Synonymous vs. non-synonymous mutations (substitutions: synonymous changed the nucleotide sequence but haven"t changed amino acid no advantage or disadvantage, non-synonymous change the nucleotide sequence and changed the amino acid. Natural selection is not the only game in town. In selection theory, all mutations would affect fitness (sometimes it is advantageous, most of the time it is harmful) Lots of them are neutral though, many mutations have no affect on phenotype because they don"t affect protein. Number of neutral mutations is proportional to the time that the two species diverged. You can go back in time just by looking at differences of sequences. Silent substitution (red) and replacement substitution (blue) If a nonsynonymous substitution would to occur, they are more likely to be detrimental, and they won"t be fixed. Proteins have such different rates because cytochrome c is an enzyme you can"t really change it.
