In mice engineered to overexpress the syndecan-1 gene in the hypothalamic region of the brain and other tissues, normal control of feeding by antisatiety peptides is disrupted, and the animals overeat and become obese. Other studies have shown that syndecan-3 may also be involved in the regulation of feeding behavior. Given the following information, which of these outcomes might you expect in experimentally manipulated mice?

I. Hypothalmic expression of syndecan-3 is increased by fasting.

II. Syndecan-3 knockout mice are resistant to diet-induced obesity.

III. Heparinase can cleave syndecan-3 to release heparin sulfate GAG chains that may suppress the activity of antisatiety peptides and feeding behavior.

Following statements are:

A. Overexpression of heparinase in mice with normal levels of syndecan-3 would result in resistance to diet-induced obesity.

B.  In mice with normal levels of syndecan-3, fasting followed by free access to a high-fat diet would lead to resistance to diet-induced obesity.

C. Lack of heparinase in mice with normal levels of syndecan-3 would result in animals that overeat and become obese.

D. Overexpression of heparinase in syndecan-3 knockout mice would reverse the resistance to diet-induced obesity.

Which of the following combination is correct?

#Question id: 3843

#Unit 3. Fundamental Processes

In DNA replication in E. coli, the enzyme primase is used to attach a 5 to 10 base ribonucleotide strand complementary to the parental DNA strand. The RNA strand serves as a starting point for the DNA polymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following results would you expect?

#Question id: 3844

#Unit 3. Fundamental Processes

The lagging strand is characterized by a series of short segments of DNA (Okazaki fragments) that will be joined together to form a finished lagging strand. The experiments that led to the discovery of Okazaki fragments gave evidence for which of the following ideas?

#Question id: 3845

#Unit 3. Fundamental Processes

The replisome, which synthesizes DNA on both leading and lagging strands, always moves toward the replication fork. This must mean that:

#Question id: 3846

#Unit 3. Fundamental Processes

A heat-sensitive DNA ligase (25°C permissive, 37°C nonpermissive) has been used to show that DNA synthesis is discontinuous. Examination of DNA replication in the presence of [3H]-thymidine in the mutant would demonstrate which of following?

#Question id: 3848

#Unit 3. Fundamental Processes

are small molecules that function as adapters between amino acids and codons.

#Question id: 3849

#Unit 3. Fundamental Processes

Which of the following is short 20 to 22-nucleotide single-stranded RNAs that block the expression of complementary or partially complementary mRNAs.