A cross between individuals with genotypes AaBbX aabb produces the following progeny:

AaBb -  83, aaBb- 21, Aabb-   19,  aa bb -77

Which of the following statements is true?

#Question id: 2875

#Unit 2. Cellular Organization

Which of the following statements is/are CORRECT from the following?

I. The chromosome of the small monkey DNA virus SV40 is a circular, double-helical DNA molecule of 5000 bp.

II. The phage Lambda genome is a linear single-stranded molecule in the virion particle.

III. Circular DNA molecules purified from both bacteria and eukaryotes are usually negatively supercoiled, having values of sigma of approximately –0.06.

IV. Prokaryotes have a special type I topoisomerase known as “DNA gyrase” that introduces, rather than removes, negative supercoils.

V. DNA disentanglement, generally catalyzed by a type II topoisomerase, is also required for a successful round of DNA replication and cell division in eukaryotes.

#Question id: 2876

#Unit 2. Cellular Organization

From the following set of statements regarding DNA topology, state whether each of the given statement is either True or False.

A.      The two strands of cccDNA can be easily separated without any breakage of bonds.

B.      Circular DNA molecules purified from bacteria and eukaryotes are usually negatively supercoiled.

C.      Interwound writhe and spiral writhe are topologically different.

D.      The organisms that live under extreme temperature conditions have been found to have positively supercoiled DNA.

E.      Negative supercoils can be thought of as a store of free energy that aids in processes that require strand separation.

#Question id: 2877

#Unit 2. Cellular Organization

What is the superhelical density of a closed-circular DNA with a length of 4,200 bp and a linking number (Lk) of 374? What is the superhelical density of the same DNA when Lk = 412? Are these molecules negatively or positively supercoiled?

A. The molecule is getting negatively supercoiled.

B. The molecule is getting positively supercoiled.

C. The superhelical density is positive.

D. The superhelical density is negative.

Which of the combinations of the above statements are correct?

#Question id: 2878

#Unit 2. Cellular Organization

Match the following types of Transposable elements with their respective types and examples found in various organisms.

#Question id: 2879

#Unit 2. Cellular Organization

Hybridization between mature mRNA and DNA can identify introns in eukaryotic genes. When mature mRNA produced by the insulin gene is hybridized with denatured chromosomal DNA, which of the following will most likely be observed?

#Question id: 2880

#Unit 2. Cellular Organization

According to the manner in which they work, three main classes of proteins that modify chromatin are recognized. Match the following classes of proteins given in COLUMN I with their respective examples in COLUMN II.