Chapter 14

In eukaryotic cells, DNA and RNA synthesis occur in a separate compartment from protein synthesis. In prokaryotic cells, both processes occur together. What advantages might there be to separating the processes? What advantages might there be to having them occur together?

You isolate a cell strain in which the joining of Okazaki fragments is impaired and suspect that a mutation has occurred in an enzyme found at the replication fork. Which enzyme is most likely to be mutated?

A frameshift mutation that results in the insertion of three nucleotides is often less deleterious than a mutation that results in the insertion of one nucleotide. Why?

If DNA of a particular species was analyzed and it was found that it contains 27 percent \(\mathrm{A},\) what would be the percentage of \(\mathrm{C} ?\) a. 27 percent b. 30 percent c. 23 percent d. 54 percent

The experiments by Hershey and Chase helped confirm that DNA was the hereditary material on the basis of the finding that: a. radioactive phage were found in the pellet b. radioactive cells were found in the supernatant c. radioactive sulfur was found inside the cell d. radioactive phosphorus was found in the cell

Bacterial transformation is a major concern in many medical settings. Why might health care providers be concerned? a. Pathogenic bacteria could introduce disease-causing genes in non-pathogenic bacteria. b. Antibiotic resistance genes could be introduced to new bacteria to create "superbugs." c. Bacteriophages could spread DNA encoding toxins to new bacteria. d. All of the above.

DNA double helix does not have which of the following? a. antiparallel configuration b. complementary base pairing c. major and minor grooves d. uracil

In eukaryotes, what is the DNA wrapped around? a. single-stranded binding proteins b. sliding clamp c. polymerase d. histones

Meselson and Stahl's experiments proved that DNA replicates by which mode? a. conservative b. semi-conservative c. dispersive d. none of the above

If the sequence of the \(5^{\prime}-3^{\prime}\) strand is AATGCTAC, then the complementary sequence has the following sequence: a. \(3^{\prime}\) -AATGCTAC-5' b. 3 '-CATCGTAA-5' c. 3'-TTACGATG-5' d. 3'-GTAGCATT-5'

How did Meselson and Stahl support Watson and Crick's double-helix model? a. They demonstrated that each strand serves as a template for synthesizing a new strand of DNA. b. They showed that the DNA strands break and recombine without losing genetic material. c. They proved that DNA maintains a doublehelix structure while undergoing semiconservative replication. d. They demonstrated that conservative replication maintains the complementary base pairing of each DNA helix.

Which of the following components is not involved during the formation of the replication fork? a. single-strand binding proteins b. helicase c. origin of replication d. ligase

Which of the following does the enzyme primase synthesize? a. DNA primer b. RNA primer c. Okazaki fragments d. phosphodiester linkage

In which direction does DNA replication take place? a. \(5^{\prime}-3^{\prime}\) b. \(3^{\prime}-5^{\prime}\) c. \(5^{\prime}\) d. \(3^{\prime}\)

A scientist randomly mutates the DNA of a bacterium. She then sequences the bacterium's daughter cells, and finds that the daughters have many errors in their replicated DNA. The parent bacterium likely acquired a mutation in which enzyme? a. DNA ligase b. DNA pol II c. Primase d. DNA pol I

The ends of the linear chromosomes are maintained by a. helicase b. primase c. DNA pol d. telomerase

Which of the following is not a true statement comparing prokaryotic and eukaryotic DNA replication? a. Both eukaryotic and prokaryotic DNA polymerases build off RNA primers made by primase. b. Eukaryotic DNA replication requires multiple replication forks, while prokaryotic replication uses a single origin to rapidly replicate the entire genome. c. DNA replication always occurs in the nucleus. d. Eukaryotic DNA replication involves more polymerases than prokaryotic replication.

During proofreading, which of the following enzymes reads the DNA? a. primase b. topoisomerase C. DNA pol d. helicase

The initial mechanism for repairing nucleotide errors in DNA is ______. a. mismatch repair b. DNA polymerase proofreading c. nucleotide excision repair d. thymine dimers

A scientist creates fruit fly larvae with a mutation that eliminates the exonuclease function of DNA pol III. Which prediction about the mutational load in the adult fruit flies is most likely to be correct? a. The adults with the DNA pol III mutation will have significantly more mutations than average. b. The adults with the DNA pol III mutation will have slightly more mutations than average. c. The adults with the DNA pol III mutation will have the same number of mutations as average. d. The adults with the DNA pol III mutation will have fewer mutations than average.

Explain Griffith's transformation experiments. What did he conclude from them?

Why were radioactive sulfur and phosphorous used to label bacteriophage in Hershey and Chase's experiments?

Provide a brief summary of the Sanger sequencing method.

Describe the structure and complementary base pairing of DNA.

Prokaryotes have a single circular chromosome while eukaryotes have linear chromosomes. Describe one advantage and one disadvantage to the eukaryotic genome packaging compared to the prokaryotes.

Imagine the Meselson and Stahl experiments had supported conservative replication instead of semiconservative replication. What results would you predict to observe after two rounds of replication? Be specific regarding percent distributions of DNA incorporating \({ }^{15} \mathrm{~N}\) and \({ }^{14} \mathrm{~N}\) in the gradient.

DNA replication is bidirectional and discontinuous; explain your understanding of those concepts.

What are Okazaki fragments and how they are formed?

If the rate of replication in a particular prokaryote is 900 nucleotides per second, how long would it take 1.2 million base pair genomes to make two copies?

Explain the events taking place at the replication fork. If the gene for helicase is mutated, what part of replication will be affected?

What is the role of a primer in DNA replication? What would happen if you forgot to add a primer in a tube containing the reaction mix for a DNA sequencing reaction?

Quinolone antibiotics treat bacterial infections by blocking the activity of topoisomerase. Why does this treatment work? Explain what occurs at the molecular level.

An adult with a history of tanning has his genome sequenced. The beginning of a protein-coding region of his DNA reads ATGGGGATATGGCAT. If the protein- coding region of a healthy adult reads ATGGGGATATGAGCAT, identify the site and type of mutation.