Dna

16) Cytosine makes up 38% of the nucleotides in a sample of DNA from an organism. Approximately, what percentage of the nucleotides in this sample will be thymine? a. 12 b. 31 c. It cannot be determined from the information provided. d. 38 e. 24

a

8) Synthesis of a new DNA strand usually begins with a. an RNA primer. b. a DNA primer. c. DNA ligase. d. a thymine dimer. e. an Okazaki fragment.

a

12) The elongation of the leading strand during DNA synthesis a. occurs in the 3' to 5' direction. b. depends on the action of DNA polymerase. c. progresses away from the replication fork. d. does not require a template strand. e. produces Okazaki fragments.

b

17) Why is the new DNA strand complementary to the 3' to 5' strands assembled in short segments? a. only short DNA sequences can extend off the RNA primers b. DNA polymerase can assemble DNA only in the 5' to 3' direction c. the replication forks block the formation of longer strands d. it is more efficient than assembling complete new stands e. DNA polymerase can assemble DNA only in the 3' to 5' direction

b

2) In a nucleotide, the nitrogenous base is attached to the sugar's ___________ carbon and the phosphate group is attached to the sugar's __________ carbon. a. 1'; 2' b. 1'; 5' c. 2'; 1' d. 1'; 3' e. 2'; 3'

b

20) Which of the following people conducted experiments that demonstrated that DNA is the genetic material of bacteriophages? a. Griffith b. Hershey and Chase c. Watson and Crick d. McCarty and MacLeod e. Franklin and Wilkins

b

7) After DNA replication is completed a. each new DNA double helix consists of two new strands. b. each new DNA double helix consists of one old DNA strand and one new DNA strand. c. one DNA double helix consists of two old strands and one DNA double helix consists of two new strands. d. each of the four DNA strands consists of some old strand parts and some new strand parts. e. there are four double helices.

b

11) What is the basis for the difference in how the leading and lagging strands of DNA molecules are synthesized? a. Polymerase can work on only one strand at a time. b. The origins of replication occur only at the 5' end. c. DNA polymerase can join new nucleotides only to the 3' end of the growing strand. d. Helicases and single-strand binding proteins (SSBPs) work at the 5' end. e. DNA ligase works only in the 3' to 5' direction.

c

19) Which of the following help to hold the DNA strands apart while they are being replicated? a. primase b. ligase c. exonuclease d. single-strand binding proteins e. DNA polymerase

d

6) Individuals with the disorder xeroderma pigmentosum are hypersensitive to sunlight because their cells have an impaired ability to a. exchange DNA with other cells. b. undergo mitosis. c. recombine homologous chromosomes during meiosis. d. repair thymine dimers. e. replicate DNA.

d

14) In analyzing the number of different bases in a DNA sample, which result would be consistent with base-pairing rules? a. G = T b. A = C c. A + T = G + T d. A = G e. A + G = C + T

e

15) 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? a. nuclease, telomerase, primase b. telomerase, helicase, single-stranded binding protein (SSBP) c. telomerase, primase, DNA polymerase d. DNA ligase, replication fork proteins, adenylyl cyclase e. nuclease, DNA polymerase, DNA ligase

e