|
Title: Three-linked genes map Post by: JaeYang on Oct 8, 2014 An organism of the genotype AaBbCc was testcrossed to a triply recessive organism (aabbcc). The genotypes of the progeny are presented in the following table.
20 AaBbCc 5 AaBbcc 5 aabbCc 20 aabbcc 20 AabbCc 5 Aabbcc 5 aaBbCc 20 aaBbcc PART A If these three genes were all assorting independently, how many genotypic and phenotypic classes would result in the offspring, and in what proportion, assuming simple dominance and recessiveness in each gene pair? A) 6, 1:1:1:1:1:1 B) 4, 1:1:1:1 C) 2, 1:1 D) 8, 1:1:1:1:1:1:1:1 PART B Answer part (a) again, assuming the three genes are so tightly linked on a single chromosome that no crossover gametes were recovered in the sample of offspring. A) 4, 1:1:1:1 B) 8, 1:1:1:1:1:1:1:1 C) 2, 1:1 D) 6, 1:1:1:1:1:1 PART C What can you conclude from the actual data about the location of the three genes in relation to one another? A) The A and C loci are linked and locus B assorts independently from both A and C loci. B) The A and B loci are linked and locus C assorts independently from both A and B loci. C) The B and C loci are linked and locus A assorts independently from both B and C loci. PART D How far apart are the linked genes? A) 5 map units B) 10 map units C) 15 map units D) 20 map units E) 40 map units Title: Re: Three-linked genes map Post by: chuchootra1n on Oct 17, 2014 a) 2^n = 8 classes -> 1:1:1:1:1:1:1:1
b) 2 classes -> 1:1 c) C assorts independently d) 20 map units |