Question

In cactus, the relationship between Gene S and Gene N is known to be epistatic. Gene S controls the sharpness of spines in a type of cactus. Cacti with the dominant allele, S, have sharp spines, whereas homozygous recessive ss cacti have dull spines. At the same time, the second gene, N, determines whether or not cacti have spines. Homozygous recessive nn cacti have no spines at all. Briefly explain why this genetic interaction is considered epistasis. Which gene is considered epistatic to the other?

Briefly describe the characteristics of eukaryotic telomeres that cause them to replicate differently than the rest of the chromosome. What will be the result of this replication challenge over a lifetime of cell duplications? How might the enzyme telomerase affect cellular aging?

Answer 1

Briefly explain why this genetic interaction is considered epistasis. Which gene is considered epistatic to the other?

This interaction is considered as epistasis because in this case one gene can suppress the expression of other gene. Here gene “N” is epistatic to gene “S” because of presence or absence of gene “N” will determine the traits expressed by the allele of “S” gene.

Briefly describe the characteristics of eukaryotic telomeres that cause them to replicate differently than the rest of the chromosome.

Eukaryotic telomeres terminate with 3′ single-stranded-DNA overhang due to this the telomere possess multiple single and double binding telomere strands.

What will be the result of this replication challenge over a lifetime of cell duplications? How might the enzyme telomerase affect cellular aging?

Telomerase enzyme restricts the shortening of telomere which is corelated with cell aging