Quiz Unit 6 Ch 16 Inheritance

Thymine makes up 28% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be guanine?

22%

At a specific area of a chromosome, the sequence of nucleotides below is present where the chain opens to form a replication fork: 3¢ C C T A G G C T G C A A T C C 5¢ An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

5¢ A C G U U A G G 3¢

Referring to the figure, what bases will be added to the primer as DNA replication proceeds?

5¢ A, G, A, C, G, A, C 3¢

Cytosine makes up 42% of the nucleotides in a sample of DNA from an organism. Approximately what percentage of the nucleotides in this sample will be thymine?

8%

In analyzing the number of different bases in a DNA sample, which result would be consistent with the base-pairing rules?

A + G = C + T

A space probe returns with a culture of a microorganism found on a distant planet. Analysis shows that it is a carbon-based life-form that has DNA. You grow the cells in 15N medium for several generations and then transfer them to 14N medium. Which pattern in the figure would you expect if the DNA was replicated in a conservative manner?

B

Which of the following facts did Hershey and Chase make use of in trying to determine whether DNA or protein is the genetic material?

DNA contains phosphorus, whereas protein does not

A biochemist isolates, purifies, and combines in a test tube a variety of molecules needed for DNA replication. When she adds some DNA to the mixture, replication occurs, but each DNA molecule consists of a normal strand paired with numerous segments of DNA a few hundred nucleotides long. What has she probably left out of the mixture?

DNA ligase

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 during DNA replication?

DNA polymerase

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?

DNA polymerase is an enzyme that synthesizes leading and lagging strands during replication only in one direction.

In DNA replication, the resulting daughter molecules contain one strand of the original parental DNA and one new strand. What is the explanation for this phenomenon?

DNA replication is semiconservative.

Which of the following structural characteristics is most critical for the association between histones and DNA?

Histones are positively charged

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

It joins Okazaki fragments together

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine, and cytosine forms hydrogen bonds with guanine. What is the significance of the structural arrangement?

It permits complementary base pairing.

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

Meselson and Stahl

In his transformation experiments, what phenomenon did Griffith observe?

Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form

In E. coli replication 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 DNApolymerase that replicates the DNA. If a mutation occurred in the primase gene, which of the following would you expect?

Replication would not occur on either the leading or lagging strand.

Telomere shortening puts a limit on the number of times a cell can divide. Research has shown that telomerase can extend the life span of cultured human cells. How might adding telomerase affect cellular aging?

Telomerase eliminates telomere shortening and retards aging

Which of the following statements correctly describes the difference between the leading strand and the lagging strand in DNA replication?

The leading strand is synthesized continuously in the 5¢ ® 3¢ direction, while the lagging strand is synthesized discontinuously in the 5¢ ® 3¢ direction.

Hershey and Chase used a DNA-based virus for their work. How might the results have been different if they had used an RNA virus?

With an RNA virus, radioactive RNA would have been in the final pellet.

The elongation of the leading strand during DNA synthesis

depends on the action of DNA polymerase

In a nucleosome, the DNA is wrapped around

histones

You briefly expose bacteria undergoing DNA replication to radioactively labeled nucleotides. When you centrifuge the DNA isolated from the bacteria, the DNA separates into two classes. One class of labeled DNA includes very large molecules (thousands or even millions of nucleotides long), and the other includes short stretches of DNA (several hundred to a few thousand nucleotides in length). Which two classes of DNA do these different samples represent?

leading strands and Okazaki fragments

The spontaneous loss of amino groups from adenine in DNA results in hypoxanthine, an uncommon base, opposite thymine. What combination of proteins could repair such damage?

nuclease, DNA polymerase, DNA ligase

Which of the following lists represents the order of increasingly higher levels of organization of chromatin?

nucleosome, 30-nm chromatin fiber, looped domain

Semiconservative replication involves a template. What is the template?

one strand of the DNA molecule

Which of the following types of molecules help to hold the DNA strands apart while they are being replicated?

single-strand DNA binding proteins

What are telomeres?

the ends of linear chromosomes