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


A) nucleosome, 30-nm chromatin fiber, looped domain
B) looped domain, 30-nm chromatin fiber, nucleosome
C) looped domain, nucleosome, 30-nm chromatin fiber
D) nucleosome, looped domain, 30-nm chromatin fiber
E) 30-nm chromatin fiber, nucleosome, looped domain

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  Figure 13.1 -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 Figure 13.1 would you expect after one round of DNA replication if the DNA was replicated in a conservative manner? A)  A B)  B C)  C D)  D E)  E Figure 13.1 -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 Figure 13.1 would you expect after one round of DNA replication if the DNA was replicated in a conservative manner?


A) A
B) B
C) C
D) D
E) E

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Which of the following enzymes synthesizes short segments of RNA?


A) helicase
B) DNA polymerase III
C) ligase
D) DNA polymerase I
E) primase

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Which of the following modifications is most likely to alter the rate at which a DNA fragment moves through a gel during electrophoresis?


A) altering the nucleotide sequence of the DNA fragment without adding or removing nucleotides
B) radioactively labeling the cytosine bases within the DNA fragment
C) increasing the length of the DNA fragment
D) leaving the length of the DNA fragment the same

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During DNA replication, which of the following enzymes separates the DNA strands during replication?


A) helicase
B) DNA polymerase III
C) ligase
D) DNA polymerase I
E) primase

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Which of the following statements accurately describes why Taq polymerase is used in PCR?


A) It is heat stable and can withstand the heating step of PCR.
B) Only minute amounts are needed for each cycle of PCR.
C) It binds more readily than other polymerases to the primers.
D) It has regions that are complementary to the primers.
E) It is heat stable, and it binds more readily than other polymerases to the primers.

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Given the damage caused by UV radiation, the kind of gene affected in those with xeroderma pigmentosum is one whose product is involved with


A) mending of double-strand breaks in the DNA backbone.
B) breakage of cross-strand covalent bonds.
C) the ability to excise damage to single-stranded DNA and replace it.
D) the removal of damaged areas of double-stranded DNA.
E) causing affected skin cells to undergo apoptosis.

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


A) the sequence of bases
B) phosphate-sugar backbones
C) complementary pairing of bases
D) different five-carbon sugars

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How is transformation in bacteria most accurately described?


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) the type of semiconservative replication shown by DNA
E) assimilation of external DNA into a cell

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


A) the nucleoside triphosphates have the sugar deoxyribose; ATP has the sugar ribose.
B) the nucleoside triphosphates have two phosphate groups; ATP has three phosphate groups.
C) ATP contains three high-energy bonds; the nucleoside triphosphates have two.
D) ATP is found only in human cells; the nucleoside triphosphates are found in all animal and plant cells.
E) triphosphate monomers are active in the nucleoside triphosphates, but not in ATP.

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


A) One of the daughter cells, but not the other, would have radioactive DNA.
B) Neither of the two daughter cells would be radioactive.
C) All four bases of the DNA would be radioactive.
D) Radioactive thymine would pair with nonradioactive guanine.
E) DNA in both daughter cells would be radioactive.

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


A) primase
B) ligase
C) DNA polymerase
D) single-strand binding proteins
E) nuclease

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In an analysis of the nucleotide composition of DNA, 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

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


A) the diameter of the helix
B) the rate of replication
C) the sequence of nucleotides
D) the frequency of A versus T nucleotides

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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) one high-density and one low-density band
B) one intermediate-density band
C) one high-density and one intermediate-density band
D) one low-density and one intermediate-density band

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Which of the following statements correctly describes one characteristic of histones?


A) Each nucleosome consists of two molecules of histone H1.
B) Histone H1 is not present in the nucleosome bead; instead, it draws the nucleosomes together.
C) The carboxyl end of each histone extends outward from the nucleosome and is called a "histone tail."
D) Histones are found in mammals, but not in other animals or in plants or fungi.

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


A) DNA without attached histones
B) DNA with H1 only
C) the 10-nm chromatin fiber
D) the 30-nm chromatin fiber

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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.
E) RNA includes ribose, whereas DNA includes deoxyribose sugars.

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An Okazaki fragment has which of the following arrangements?


A) primase, polymerase, ligase
B) 3' RNA nucleotides, DNA nucleotides 5'
C) 5' RNA nucleotides, DNA nucleotides 3'
D) DNA polymerase I, DNA polymerase III
E) 5' DNA to 3'

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What is the function of DNA polymerase III?


A) to unwind the DNA helix during replication
B) to seal together the broken ends of DNA strands
C) to add nucleotides to the 3' end of a growing DNA strand
D) to degrade damaged DNA molecules
E) to rejoin the two DNA strands (one new and one old) after replication

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