Question

Experiment Interpretation Sheet 1. What is the chromosome number (2N) that you have observed in Ae, aegypti mitotic chromosome preparations? 2. To what type of the chromosomes based on the centromere position do Ae, aegypti chromosomes belong? (circle one): metacentric submetacentric acrocentric telocentric 3. Which stage of mitosis do you think is more suitable for mapping? Why? 4. What is the chromosome number and the karyotype of An, gambiae and An. stephens? 5. What is the number of chromosome arms in polytene chromosomes of An. stephensi? 6. Why polytene chromosomes are much bigger than mitotic chromosomes? 7. Why polytene chromosomes form loops in case of the inversion? 8. What are the differences between the chromosomes in genus Anopheles and Aedes?

I need help answering questions #2-8.

Answer 1

ANSWER 6-

Polytene chromosomes are formed when the products of multiple rounds of S- phase remain tightly associated to form one supersized chromosome.In particular polytene chromosomes are found in a specific subset of endopolyploid cells,which have undergone a varient cell cycle known as the endocycle.During endocycle,cells undergo successive genome replications without any intervening nuclear envelope breakdown.Because the number of endocycles can vary between tissues and organisms,polytene chromosomes cover an impressive range of ploidy from those that are only reduplicated a single time to chromosomes made of many thousands or even millions of genome copies.Polytene chromosomes can form in cells that undergo transient nuclear envelope breakdown without subsequent chromosome seperation.