Question

For problems 38 and 39 assume that in squashes the difference in fruit weight between a 3-1b type and a 6-lb type results from three independently segregating allele pairs with each capital letter contributing a half pound to the weight of the squash. 38. What is the range in fruit weight of the offspring in the following cross: Aa Bb Cc x Aa Bb Cc 39. A farmer develops a 4-lb variety of the squash that is true breeding. What can you deduce about the genotype of his variety? [write out the genotype(s) of any 4-lb variety that is true breeding] 40. Genes d and p occupy loci 10 mu apart in the same autosomal linkage group. Gene h is in a different autosomal linkage group. What types of offspring are expected, and what is the probability of each, when the individuals of the following genotypes are testcrossed? DP/d pH/h 41. Genes A and B are linked, with 20% recombination. What would be the phenotypes , and the probability of each among the progeny of the following cross? A B/a bx a b/a b 42. What base sequence would be complementary to the following DNA strand? 5' AATTCCGG 3'

Answer 1

38. Range in fruit weight: 0.5-lb to 3-Ib.

39. Genotypes of 4-lb variety of the squash:

• AaBbcc
• AabbCc
• aaBbCc
• AAbbcc
• aaBBcc
• aabbCC

41. Gametes: (AB),(ab). (ab),(ab)

Cross Progeny: AB/ab, AB/ab. ab/ab, ab/ab

Cross Ratio: 2:2 Or 1:1

Probability of each progeny: 50%

42. Complementary base sequence: 3' TTAAGGCC 5'