“Linkage” refers to a situation where ___ 1 __ genes are present on the same ___
ID: 82563 • Letter: #
Question
“Linkage” refers to a situation where ___1__ genes are present on the same ___2__, and hence leads to a deviation from the classic Mendelian ratio of ___3__.
When working with linkage, we don’t use the traditional F1 x F1 cross – instead, we use a ___4__. Under these circumstances, genes on separate chromosomes will appear in the progeny in a ___5__ ratio, indicative of the Mendelian principle of ___6__. Another way to describe the behavior of genes on separate chromosomes is with reference to “parental” and “___7__” progeny classes, with each occurring ___8__% of the time.
The most useful representation of the linkage ratio is the ratio of R/total (x100), giving you a value called a ___9__.
It is worth noting that the ratio of R/total never exceeds 50%. The reason for this is ___10__. For this reason, genes far part on a chromosome cannot be distinguished from genes on separate chromosomes using linkage analysis; that is, genes very far apart on a chromosome will appear to exhibit the Mendelian principle of ___11__.
Explanation / Answer
When working with linkage, we don’t use the traditional F1 x F1 cross – instead, we use a three-point testcross. Under these circumstances, genes on separate chromosomes will appear in the progeny in a 1 : 1 : 1 : 1 ratio, indicative of the Mendelian principle of Mendel's law of segregation. Another way to describe the behavior of genes on separate chromosomes is with reference to “parental” and “F1” progeny classes, with each occurring _____% of the time.
The most useful representation of the linkage ratio is the ratio of R/total (x100), giving you a value called a map units (mu).
It is worth noting that the ratio of R/total never exceeds 50%. The reason for this is crossovers between genes that results in chromosomal exchange. For this reason, genes far part on a chromosome cannot be distinguished from genes on separate chromosomes using linkage analysis; that is, genes very far apart on a chromosome will appear to exhibit the Mendelian principle of Independent assortment.
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