BIOC51H3 Lecture Notes - Lecture 8: Zygosity, Mutation Rate

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BGYB51H3 Lecture 8-9 Notes
-natural selection reduces variation in populations because it removes unfavourable variance
-mutation is essential for evolution to proceed and increase variation
-two or more alleles for a gene causes a polymorphic gene
-changes in the base sequence of DNA are called mutations
-selection varies across a latitudinal gradient and indicates variation
-variation can be measured through polymorphism and mean heterozygosity
-point mutations generate new alleles through substituting bases
-the fate of a new allele depends on its fitness effect
-neutral alleles may be maintained, lost, or fixed by chance
-mutations in non-coding regions of DNA cause neutral fitness
-replacement substitutions may result in an amino acid with similar properties as the expected
amino acid, therefore not affecting phenotype
-accumulation of mutations tends to decrease fitness causing less survival to sexual maturity
-mutations decrease fitness because the probability of reducing functions is higher
-most mutations arise in a heterozygous form
-mutation rate is the % of A alleles that mutate into a alleles per generation
-observing genetic change and phenotypic effect are used in determining mutation rates
-multicellular generations such as humans have higher mutation rates
-mutation rate per cell division may be similar across all taxa (both unicellular and multicellular)
-gametes are important in causing mutation in offspring ~}u]oo]vv}v[µ
mutation in offspring)
-fathers are more likely than mothers to transmit point mutations
-the rate of mutation is underestimated due to only observing detectable phenotypic changes
-similar phenotypic effects can be due to a variety of different mutational changes
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Document Summary

Natural selection reduces variation in populations because it removes unfavourable variance. Mutation is essential for evolution to proceed and increase variation. Two or more alleles for a gene causes a polymorphic gene. Changes in the base sequence of dna are called mutations. Selection varies across a latitudinal gradient and indicates variation. Variation can be measured through polymorphism and mean heterozygosity. Point mutations generate new alleles through substituting bases. The fate of a new allele depends on its fitness effect. Neutral alleles may be maintained, lost, or fixed by chance. Mutations in non-coding regions of dna cause neutral fitness. Replacement substitutions may result in an amino acid with similar properties as the expected amino acid, therefore not affecting phenotype. Accumulation of mutations tends to decrease fitness causing less survival to sexual maturity. Mutations decrease fitness because the probability of reducing functions is higher. Mutation rate is the % of a alleles that mutate into a alleles per generation.

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