BIOL 121 Chapter 16

In an analysis of the nucleotide composition of DNA in any organism, which of the following will be found? A. A = C B. A = G and C = T C. A + C = G + T D. G + C = T + A

C. A + C = G + T

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. A. the 5' phosphate B. C6 C. the 3' OH D. a nitrogen from the nitrogen-containing base

C. the 3' OH

How do we describe transformation of bacteria? A. the creation of a strand of DNA from an RNA molecule B. the creation of a strand of RNA from a DNA molecule C. the infection of cells by a phage DNA molecule D. assimilation of external DNA into a cell

D. assimilation of external DNA into a cell

DNA duplication during the S phase of the cell cycle occurs through the ______ mode of replication. A. conservative B. allelic C. dispersive D. genotypic E. semi-conservative

E. semi-conservative

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 _____. A. leading strands and Okazaki fragments B. lagging strands and Okazaki fragments C. Okazaki fragments and RNA primers D. leading strands and RNA primers

A. leading strands and Okazaki fragments

The leading and the lagging strands differ in that _____. A. 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 B. the leading strand is synthesized by adding nucleotides to the 3' end of the growing strand, and the lagging strand is synthesized by adding nucleotides to the 5' end C. the lagging strand is synthesized continuously, whereas the leading strand is synthesized in short fragments that are ultimately stitched together D. the leading strand is synthesized at twice the rate of the lagging strand

A. 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

In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts? A. DNA contains sulfur, whereas protein does not. B. DNA contains phosphorus, whereas protein does not. C. DNA contains nitrogen, whereas protein does not. D. DNA contains purines, whereas protein includes pyrimidines.

B. DNA contains phosphorus, whereas protein does not.

What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? A. It synthesizes the RNA primer. B. It joins Okazaki fragments together. C. It unwinds the parental double helix. D. It stabilizes the unwound parental DNA.

B. It joins Okazaki fragments together.

Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons? A. Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not. B. Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have multiple. C. The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes. D. Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not.

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

What is meant by the description "antiparallel" regarding the strands that make up DNA? A. The twisting nature of DNA creates nonparallel strands. B. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand. C. Base pairings create unequal spacing between the two DNA strands. D. One strand contains only purines and the other contains only pyrimidines.

B. The 5' to 3' direction of one strand runs counter to the 5' to 3' direction of the other strand.

Within a double-stranded DNA molecule, adenine forms hydrogen bonds with thymine and cytosine forms hydrogen bonds with guanine. This arrangement _____. A. allows variable width of the double helix B. permits complementary base pairing C. determines the tertiary structure of a DNA molecule D. determines the type of protein produced

B. permits complementary base pairing

In E. coli, which enzyme catalyzes the elongation of a new DNA strand in the 5' → 3' direction? A. primase B. DNA ligase C. DNA polymerase III D. helicase

C. DNA polymerase III

Eukaryotic telomeres replicate differently than the rest of the chromosome. This is a consequence of which of the following? A. the evolution of telomerase enzyme B. DNA polymerase that cannot replicate the leading strand template to its 5' end C. gaps left at the 5' end of the lagging strand D. gaps left at the 3' end of the lagging strand because of the need for a primer

C. gaps left at the 5' end of the lagging strand

During replication of double-stranded DNA, the strands are replicated at different rates and gives rise to the leading and lagging strands. The disparity exists because ______. A. DNA polymerase I replicates DNA slower than DNA Polymerize III B. Ligase is directionally specific C. Topoisomerase functions best at 37° C D. DNA can only be synthesized in the 5' to 3' direction E. the DNA primer can only bind to one DNA strand at a time

D. DNA can only be synthesized in the 5' to 3' direction

Which of these mechanisms ensures that the DNA sequence in the genome remains accurate? A. Complementary base pairing during DNA replication B. Proofreading during DNA replication C. Mismatch repair D. Excision repair E. All of the above

E. All of the above

True or False: Heterochromatin is transcriptionally active DNA whereas euchromatin is transcriptionally silent DNA.

False. During interphase, heterochromatin are highly condensed chromatin (centromeres and telomeres), whereas euchromatin are loosely packed chromatin.

True or False: Okazaki fragments are twice as long as leading strand fragments.

False. Okazaki fragments are half as long or shorter than leading strand fragments.

True or False: The anti-parallel structure of DNA along with the base pairing rules suggested the conservative model of DNA replication.

False. The anti-parallel structure of DNA along with the base pairing rules suggested the SEMICONSERVATIVE model of DNA replication. (Models of DNA replication: Conservative, Semiconservative, Dispersive)

True or False: A current model of DNA replication suggest that the DNA is reeled into a stationary DNA replication synthesis complex as opposed to the complex moving down the length of the DNA.

True

True or False: Watson and Crick used Chargaff's rules to devise the complementary base pairing rules and to suggest an anti-parallel orientation of the DNA double helix.

True