Chapter 16

In his transformation experiments, what did Griffith observe?

How do we describe transformation in bacteria?

After mixing a heat-killed, phosphorescent strain of bacteria with a living nonphosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait?

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

Which of the following investigators was/were responsible for the following discovery? In DNA from any species, the amount of adenine equals the amount of thymine, and the amount of guanine equals the amount of cytosine.

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?

Which of the following can be determined directly from X-ray diffraction photographs of crystallized DNA?

It became apparent to Watson and Crick after completion of their model that the DNA molecule could carry a vast amount of hereditary information in which of the following?

In an analysis of the nucleotide composition of DNA, which of the following will be found?

Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?

What is meant by the description "antiparallel" regarding the strands that make up DNA?

Suppose you are provided with an actively dividing culture of E. coli bacteria to which radioactive thymine has been added. What would happen if a cell replicates once in the presence of this radioactive base?

An Okazaki fragment has which of the following arrangements?

In E. coli, there is a mutation in a gene called dnaB that alters the helicase that normally acts at the origin. Which of the following would you expect as a result of this mutation?

Which enzyme catalyzes the elongation of a DNA strand in the 5' → 3' direction?

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following?

The enzyme telomerase solves the problem of replication at the ends of linear chromosomes by which method?

The DNA of telomeres has been found to be highly conserved throughout the evolution of eukaryotes. What does this most probably reflect?

An RNA primer is formed starting at the underlined T (T) of the template. Which of the following represents the primer sequence?

Polytene chromosomes of Drosophila salivary glands each consist of multiple identical DNA strands that are aligned in parallel arrays. How could these arise?

To repair a thymine dimer by nucleotide excision repair, in which order do the necessary enzymes act?

What is the function of DNA polymerase III?

The difference between ATP and the nucleoside triphosphates used during DNA synthesis is that

The leading and the lagging strands differ in that

) A new DNA strand elongates only in the 5' to 3' direction because

What is the function of topoisomerase?

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

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

Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight. This occurs because their cells are impaired in what way?

Which of the following would you expect of a eukaryote lacking telomerase?

Use the following list of choices for the following questions: I. helicase II. DNA polymerase III III. ligase IV. DNA polymerase I V. primase 31) Which of the enzymes removes the RNA nucleotides from the primer and adds equivalent DNA nucleotides to the 3' end of Okazaki fragments?

Which of the enzymes separates the DNA strands during replication?

Which of the enzymes covalently connects segments of DNA?

Which of the enzymes synthesizes short segments of RNA?

Which of the following sets of materials are required by both eukaryotes and prokaryotes for replication?

Studies of nucleosomes have shown that histones (except H1) exist in each nucleosome as two kinds of tetramers: one of 2 H2A molecules and 2 H2B molecules, and the other as 2 H3 and 2 H4 molecules. Which of the following is supported by this data?

In a linear eukaryotic chromatin sample, which of the following strands is looped into domains by scaffolding?

Which of the following statements describes the eukaryotic chromosome?

If a cell were unable to produce histone proteins, which of the following would be a likely effect?

Which of the following statements is true of histones?

Why do histones bind tightly to DNA?

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

Which of the following statements describes chromatin?

In the late 1950s, Meselson and Stahl grew bacteria in a medium containing "heavy" nitrogen (15N) and then transferred them to a medium containing 14N. Which of the results in the figure above would be expected after one round of DNA replication in the presence of 14N?

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 above would you expect if the DNA was replicated in a conservative manner?

Once the pattern found after one round of replication was observed, Meselson and Stahl could be confident of which of the following conclusions?

In an experiment, DNA is allowed to replicate in an environment with all necessary enzymes, dATP, dCTP, dGTP, and radioactively labeled dTTP (3H thymidine) for several minutes and then switched to nonradioactive medium. It is then viewed by electron microscopy and autoradiography. The figure above represents the results. Which of the following is the most likely interpretation?

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?

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). These two classes of DNA probably represent

In his work with pneumonia-causing bacteria and mice, Griffith found that

What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized?

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

The elongation of the leading strand during DNA synthesis

In a nucleosome, the DNA is wrapped around

E. coli cells grown on 15N medium are transferred to 14N medium and allowed to grow for two more generations (two rounds of DNA replication). DNA extracted from these cells is centrifuged. What density distribution of DNA would you expect in this experiment?

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?

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?