Ch. 15 Study Questions

In the accompanying figure, which is the template strand?

A

For a science fair project, two students decided to repeat the Hershey and Chase experiment, with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why won't this experiment work?

Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.

In the accompanying figure, which structure causes the two strands of DNA to separate?

B

Identify the lagging strand during duplication of DNA starting from a double helix in the accompanying figure.

C

Refer to the figure associated with this question. Which structure is responsible for stabilizing DNA in its single-stranded form?

C

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?

DNA contains phosphorus, whereas protein does not.

DNA contains the template needed to copy itself, but it has no catalytic activity in cells. What catalyzes the formation of phosphodiester bonds between adjacent nucleotides in the DNA polymer being formed?

DNA polymerase

In the figure associated with this question, which of the three types of viruses shown would you expect to include a capsid(s)?

I, II, and III

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication?

It joins Okazaki fragments together.

Who performed classic experiments that supported the semiconservative model of DNA replication?

Meselson and Stahl

What is a major difference between eukaryotic DNA replication and prokaryotic DNA replication?

Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have multiple origins of replication.

A bacterium is infected with an experimentally constructed bacteriophage composed of the T2 phage protein coat and T4 phage DNA. The new phages produced would have ________.

T4 protein and T4 DNA

What appears to be a dark side to telomerase activity with regard to human health?

Telomerase is active in most cancer cells.

The DNA of telomeres has been highly conserved throughout the evolution of eukaryotes. This most likely reflects ________.

a critical function of telomeres

Which of the following characteristics, structures, or processes is common to bacteria and viruses?

genetic material composed of nucleic acid

DNA replication is highly accurate. It results in about one mistake per billion nucleotides. For the human genome, how often would errors occur?

on average, six times each time the entire genome of a cell is replicated

Semiconservative replication involves a template. What is the template?

one strand of the DNA molecule

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement ________.

permits complementary base pairing

Which of the following help(s) to hold the DNA strands apart while they are being replicated?

single-strand DNA binding proteins

In the polymerization of DNA, a phosphodiester bond is formed between a phosphate group of the nucleotide being added and ________ of the last nucleotide in the polymer.

the 3' OH

What is a telomere?

the ends of linear chromosomes

The leading and the lagging strands differ in that ________.

the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

Viruses ________.

use the host cell to copy themselves and make viral proteins