Match the following.

Column I	Column II	Column III
A. G Protein–Coupled Receptors That Activate PDE	i. cAMP	a. Increase in conversion of glycogen to glucose
B. G Protein–Coupled Receptors That Activate Adenylyl Cyclase	ii. cGMP	b. Hyperpolarization or depolarization of photoreceptor membrane
C. G Protein–Coupled Receptors That inhibit Adenylyl Cyclase	iii. DAG	c. activates genes necessary for cell division
D. G Protein–Coupled Receptors That Trigger Elevations in Cytosolic and Mitochondrial Calcium		d. increase in K+ permeability hyperpolarizes the membrane

Which one of the following is correct?

#Question id: 2871

#Unit 2. Cellular Organization

With respect to X-chromosome inactivation in females, which, if any, of the following statements is incorrect?

#Question id: 2872

#Unit 2. Cellular Organization

Concerning disorders resulting from unstable expansion of tandem oligonucleotide repeats, which, if any of the following statements is false.

A) The expansions can occur in coding DNA in some cases, and in noncoding DNA in other cases.

B) The repeats are of a variable number of nucleotides (from three to six) in both coding DNA and noncoding DNA.

C) The expansions in noncoding DNA are generally much larger in size than those in coding DNA.

D) The expanded arrays in noncoding DNA always result in loss of function of the host gene or of a neighboring gene.

#Question id: 2873

#Unit 2. Cellular Organization

With reference to aberrant methylation of bases which of the following statements, if any, is false?

#Question id: 2874

#Unit 2. Cellular Organization

Match one item from numbered group A with a lettered item from group B.

#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.