Question

Total fingerprint ridge count exemplifies a polygenic inheritance pattern. Penrose (1969) and others have suggested that a minimum of seven gene loci contribute to TRC, but a fourlocus model is hypothesized in the problems that follow. Thus, AABBCCDD represents the genotype for maximum ridge count and aabbccdd symbolizes the genotype for the minimum ridge count. Assume that each active (dominant) allele adds 12 ridges to the TRC of the male and 9 to the TRC of the female and that having the genotype aabbccdd produces a baseline TRC of 80 for males and 70 for females. (one answer is given below to clarify any issues with these instructions).

Predict the TRC for each of the following individuals.

Genotype                                         Male                                                   Female

AABBCCDD                          answer = 176                                    answer = 142

AabbCcDd                             answer = 116                                    answer = 97

AaBbCcDD                            answer = 140                                    answer = 115

aaBbCCDd                            answer = 128                                    answer = 106

9a. Write the genotypes of both parents (the parental cross) who are heterozygous for all four genes or loci (i.e. tetrahybrid cross).

b. Write the genotype of a child (from the cross above in Question 9a) who has the minimum number of active alleles possible.

c. What are the TRCs for the parents and their child above (assume that the child is a male)?

Parents:

Male Child:

d. Calculate the probability that these parents (above in 9a) would produce a child with a single active allele assuming independent assortment of the 4 loci. Show your calculations.

Please help me with all of question 9 and show your working out so I can understand, especially with 9D. Thank you

Answer 1

The questions are based on crossing of heterozygous parents and calculation of TRC under specified cases.

A reference of the tetrahybrid cross is given below: For AaBbCcDd x AaBbCcDdusing the above punnett square and the given information, we can deduce the answers to the questions-