Use the information in the pedigree below and the information in the southern bl

Question

Use the information in the pedigree below and the information in the southern blot of the RFLPs of the gene associated with the disease to answer the following questions. Individuals affected by the disease are coded black. Assume penetrance for the disease genotype is 90%.

A. Based on the information in the pedigree and blot what is the most likely mode of inheritance of the disease. Provide two points of evidence that support your answer. (2)

B. Which band in the gel is associated with the disease? In other words, which band represents the allele that causes the disease? (long band or short band) (1)

C. What is the probability that II-4 is affected? (1)

D. What is the probability that III-3 will be affected? (2)

E. If II-4 and II-5 had 4 children total. What is the probability that 2 would be affected and 2 would be unaffected? (leave as an unreduced equation) (2)

Explanation / Answer

ANSWER: (A)

Based on the given pedigree graph the mode of inheritance of disease would be heterogygous recessive. Since, in heterogygous recessive inheritance the affected alleles show their effect if they present on both the different alleles of male (due to x and y chromosome) but females not affected by this type of inheritance (due to presence of two x chromosomes). The inheritance that disease is possible when both the parents are carrier for that disease. Hence, in the given pedigree graph only one male is diseased in second generation but second male is not affected because his mother would be not a carrier of that disease.

ANSWER: (B)

In southern bloting of RFLPs of associated genes shows two type of bands in the gel medium. The long band of genes is placed far away with affected alleles in the second row bloting pattern.

ANSWER: (C)

The probability of disease in the ll-4 is 50%. Since, his father (ll-4) is carrier or has diseased allele and his mother would be a carrier that one or not. Hence, the probability of inheritance is depend on his mother. There is a 50% chances whether a carrier than ll-4 would be affected.

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