Mutations

Genetics as it applies to evolution, molecular biology, and medical aspects.

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Casey
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Mutations

Post by Casey » Thu Sep 11, 2008 10:39 pm

If a mutation were to affect a population over time would that become and evolutionary change?

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canalon
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Post by canalon » Fri Sep 12, 2008 2:49 am

the quesion is not clear. If a mutation become fixed in a population, it is an evolutionary change indeed. Affect seems inapropriate in this sentence.
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Casey
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Post by Casey » Fri Sep 12, 2008 3:20 am

Then how would a mutation affect a population over time?

wbla3335
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Re: Mutations

Post by wbla3335 » Fri Sep 12, 2008 7:15 am

If a new mutation is neutral, that is, if it doesn't cause a change in amino acid or it causes a substitution that has no effect on the function of the protein, then the population will not be immediately affected (but a subsequent mutation could, in combination with the first mutation, be of significance). If the mutation reduces fitness, then negative selection should remove it fairly quickly from the population, so the population remains unaffected. If the mutation increases fitness, then positive selection will increase its frequency in the population, to the benefit of the population over time. Sometimes, though, mutations that by themselves can reduce fitness occur in a gene that lies close to another gene that has an allele that increases fitness, so the "bad" mutation can hitch a ride with the "good" allele of the other gene and increase in frequency in the population, even though it is bad.

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