Gene conversion can be observed in fungi by identifying aberrant ratios in the ascus. Which of the following represent possible aberrant ratios caused when there is no mismatch repair of base-pair mistakes in the heteroduplex region?

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Quizplus · Accepted Answer

Aberrant ratios in the ascus can result from gene conversion events in which one allele converts the other, leading to a heterozygous region. In the absence of mismatch repair, the heteroduplex region may contain base-pair mistakes, which can result in unequal crossing over or gene conversion. The aberrant ratios resulting from gene conversion without mismatch repair can result in imbalanced segregation of alleles, leading to non-parental ditype (NPD) tetrads with a 3:1:1:3 ratio. Thus, option B (3:1:1:3) is the best choice for aberrant ratios resulting from gene conversion without mismatch repair. The other options do not fit the expected ratios resulting from gene conversion without mismatch repair.

Gene Conversion Can Be Observed in Fungi by Identifying Aberrant