roosevelt.blackboard.com 9. Suppose heterozygous Nn lizards express a condition

Question

roosevelt.blackboard.com 9. Suppose heterozygous Nn lizards express a condition called "lanky", in which the leg bones are longer than normal (normal is nn). The dominant N allele is lethal when homozygous. Two alleles of an independently segregating gene determine green (GG or Gg) versus orange (gg) skin color. What are the non-viable genotypes? From a mating between lizards heterozygous for both genes, what phenotypic classes will be represented among viable progeny, and what are the expected relative frequencies of the viable phenotypes (3.0 pts)? Phenotype classes and relative frequencies of VIABLE offspring: 10. Crossing over occurs during which phase of meiosis (0.5pts)?

Explanation / Answer

9. Since the dominant allele N is lethal when homozygous hence all genotypes contacting the dominant allele in homozygous condition will be non-viable

hence the below genotypes will be non-viable

NNGG, NNGg and NNgg

Mating between lizards heterozygous for both genes, please refer to the below table:

Therefor phenotypes that will be represented in the viable progenies are:

NnGG - Lanky & Green

NnGg - Lanky & Green

Nngg - Lanky & Orange

nnGG - Normal & Green

nnGg - Normal & Green

nngg - Normal & Orange

From the above table Considering the total number of inidviduals to be 16 - expected relative frequency for the following frequencies are as below:

lanky & green = 6/16

Lanky & Orange = 2/16

Normal & green = 3/16

Normal & Orange = 1/16

10. Crossing over occurs during the Prophase I of Meiosis

NG Ng nG ng NG NNGG NNGg NnGG NnGg Ng NNGg NNgg NnGg Nngg nG NnGG NnGg nnGG nnGg ng NnGg Nngg nnGg nngg

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