A disrupted Alu SINE element has recently inserted in heterochromatin near the c

Question

A disrupted Alu SINE element has recently inserted in heterochromatin near the centromere of chromosome 16 in humans. It does not disrupt any gene regions and appears to be selectively neutral. However, upon insertion it received a deletion spanning one terminal repeat and a basepair substitution mutation in the other terminal repeat that has immobilized the element. Worldwide this Alu insert is found in only 36% of people (as either a heterozygote (technically hemizygote) or homozygote). Over many generations, is this specific Alu insert more likely to ultimately fix or be lost from the human population? What is the exact probability this specific Alu insert will ultimately be lost from the human genome due to genetic drift?

Explanation / Answer

A) Over many generations, this specific Alu insert ismore likely to be lost from the population because due to genetic drift every finite set of genes converge to a single ancestor. And here the Alu insert is present only in 36% ofpopulation worldwide and remaining 64% constitutes the normal alleles.

B) Here there is no role of natural selection, the probability of a genetic variant in a population to lost is its frequency. Here the frequency of Alu is 36% only so probability of its fixation is only 36% as compared to remaining 64% frequency of other allele.So, 36% will get lost and 64% will get fixed after many generations.

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