Chapter 8

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1

1) A gene is best defined as

A) any random segment of DNA.

B) three nucleotides that code for an amino acid.

C) a sequence of nucleotides in DNA that codes for a functional product.

D) a sequence of nucleotides in RNA that codes for a functional product.

E) the RNA product of a transcribed section of DNA.

Answer: C

2

2) Which of the following pairs is mismatched?

A) DNA polymerase — makes a molecule of DNA from a DNA template

B) RNA polymerase — makes a molecule of RNA from an RNA template

C) DNA ligase — joins segments of DNA

D) transposase — insertion of DNA segments into DNA

E) DNA gyrase — coils and twists DNA

Answer: B

3

3) Which of the following statements is FALSE?

A) DNA polymerase joins nucleotides in one direction (5' to 3') only.

B) The leading strand of DNA is made continuously.

C) The lagging strand of DNA is started by an RNA primer.

D) DNA replication proceeds in only one direction around the bacterial chromosome.

E) Multiple replication forks are possible on a bacterial chromosome.

Answer: D

4

4) DNA is constructed of

A) a single strand of nucleotides with internal hydrogen bonding.

B) two complementary strands of nucleotides bonded A—C and G—T.

C) two strands of nucleotides running in an antiparallel configuration.

D) two strands of identical nucleotides in a parallel configuration with hydrogen bonds between them.

E) None of the answers is correct.

Answer: C

5

5) Which of the following is NOT a product of transcription?

A) a new strand of DNA

B) rRNA

C) tRNA

D) mRNA

E) None of the answers are correct; all of these are products of transcription.

Answer: A

6

6) Which of the following statements about bacteriocins is FALSE?

A) The genes coding for them are on plasmids.

B) They cause food-poisoning symptoms.

C) Nisin is a bacteriocin used as a food preservative.

D) They can be used to identify certain bacteria.

E) Bacteriocins kill bacteria.

Answer: B

7
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In Figure 8.1, which colonies are streptomycin-resistant and leucine-requiring?

A) 1, 2, 3, and 9

B) 3 and 9

C) 4, 6, and 8

D) 4 and 8

E) 5 and 6

Answer: D

8

Culture 1: F+, leucine+, histidine+

Culture 2: F-, leucine-, histidine-

8) In Table 8.1, what will be the result of conjugation between cultures 1 and 2 (reminder: F+ has a different meaning than Hfr)?

  1. A) 1 will remain the same;

2 will become F+, leucine-, histidine-

  1. B) 1 will become F-, leu+, his+;

2 will become F+, leu-, his-

  1. C) 1 will become F-, leu-, his-;

2 will remain the same

  1. D) 1 will remain the same;

2 will become F+, leu+, his+

  1. E) 1 will remain the same;

2 will become F+ and recombination may occur

Answer: A

9

9) In Table 8.1, if culture 1 mutates to Hfr, what will be the result of conjugation between the two cultures?

  1. A) They will both remain the same.
  2. B) 1 will become F+, leu+, his+;

2 will become F+, leu+, his+

  1. C) 1 will remain the same;

recombination will occur in 2

  1. D) 1 will become F-, leu+, his+;

2 will become Hfr, leu+, his+

  1. E) The answer cannot be determined based on the information provided.

Answer: C

10

10) An enzyme produced in response to the presence of a substrate is called a(n)

  1. A) inducible enzyme.
  2. B) repressible enzyme.
  3. C) restriction enzyme.
  4. D) operator.
  5. E) promoter.

Answer: A

11

11) Transformation is the transfer of DNA from a donor to a recipient cell

A) by a bacteriophage.

B) as naked DNA in solution.

C) by cell-to-cell contact.

D) by crossing over.

E) by sexual reproduction.

Answer: B

12

12) Genetic change in bacteria can be brought about by

A) mutation.

B) conjugation.

C) transduction.

D) transformation.

E) All of the answers are correct.

Answer: E

13

13) Which of the following statements regarding a bacterium that is R+ is FALSE?

A) It possesses a plasmid.

B) R+can be transferred to a cell of the same species.

C) It is resistant to certain drugs and heavy metals.

D) It is F+.

E) R+can be transferred to a different species.

Answer: D

14

14) The initial effect of ionizing radiation on a cell is that it causes

A) DNA to break.

B) bonding between adjacent thymines.

C) base substitutions.

D) the formation of highly reactive ions.

E) the cells to get hot.

Answer: D

15

15) According to the operon model, for the synthesis of an inducible enzyme to occur, the

A) end-product must not be in excess.

B) substrate must bind to the enzyme.

C) substrate must bind to the repressor.

D) repressor must bind to the operator.

E) repressor must not be synthesized.

Answer: C

16

16) Synthesis of a repressible enzyme is stopped by the

A) allosteric transition.

B) substrate binding to the repressor.

C) corepressor binding to the operator.

D) corepressor-repressor complex binding to the operator.

E) end product binding to the promoter.

Answer: D

17
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17) In Figure 8.2, if base 4 is thymine, what is base 4'?

A) adenine

B) thymine

C) cytosine

D) guanine

E) uracil

Answer: A

18
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18) In Figure 8.2, if base 4 is thymine, what is base 11' (remember the complimentary configuration of bases in DNA)?

A) adenine

B) thymine

C) cytosine

D) guanine

E) uracil

Answer: B

19
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19) In Figure 8.2, base 2 (and ONLY the base) is covalently bound/attached to

A) ribose.

B) phosphate.

C) deoxyribose.

D) thymine.

E) The answer cannot be determined based on the information provided.

Answer: C

20

20) The damage caused by ultraviolet radiation is

A) never repaired.

B) repaired during transcription.

C) repaired during translation.

D) cut out and replaced.

E) repaired by DNA replication.

Answer: D

21
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21) Refer to Table 8.2. If the sequence of amino acids encoded by a strand of DNA is

serine-alanine-lysine-leucine, what is the order of bases in the sense strand of DNA?

A) 3' UGUGCAAAGUUA

B) 3' AGACGTTTCAAT

C) 3' TCTCGTTTGTTA

D) 5' TGTGCTTTCTTA

E) 5' AGAGCTTTGAAT

Answer: B

22
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22) Refer to Table 8.2. If the sequence of amino acids encoded by a strand of DNA is

serine-alanine-lysine-leucine, the coding for the antisense strand of DNA is

A) 5' ACAGTTTCAAT.

B) 5' TCTGCAAAGTTA.

C) 3' UGUGCAAAGUUA.

D) 3' UCUCGAAAGUUA.

E) 3' TCACGUUUCAAU.

Answer: B

23
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23) Refer to Table 8.2 The anticodon for valine is

A) GUU.

B) CUU.

C) CTT.

D) CAA.

E) GTA.

Answer: D

24
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24) Refer to Table 8.2. What is the sequence of amino acids encoded by the following sequence of bases in a strand of DNA (pay attention to the polarity of the DNA here)?

3' ATTACGCTTTGC

A) leucine-arginine-lysine-alanine

B) asparagine-arginine-lysine-alanine

C) asparagine-cysteine-valine-serine

D) Translation would stop at the first codon.

E) The answer cannot be determined based on the information provided.

Answer: D

25
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25) Refer to Table 8.2. If an indeterminate frameshift mutation occurred in the sequence of bases shown below, what would be the sequence of amino acids coded for?

3' ATTACGCTTTGC

A) leucine-arginine-lysine-alanine

B) asparagine-arginine-lysine-alanine

C) asparagine-cysteine-valine-serine

D) Translation would stop at the first codon.

E) The answer cannot be determined based on the information provided.

Answer: E

26
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26) In Figure 8.3, if compound C reacts with the allosteric site of enzyme A, this would exemplify

A) a mutation.

B) repression.

C) feedback inhibition.

D) competitive inhibition.

E) transcription.

Answer: C

27

27) In Figure 8.3, if enzyme A is a repressible enzyme, compound C would

A) always be in excess.

B) bind to Enzyme A.

C) bind to the corepressor for Gene a.

D) bind to RNA polymerase.

E) bind directly to gene a.

Answer: C

28

28) In Figure 8.3, if enzyme A is an inducible enzyme,

A) compound C would bind to the repressor for Gene a.

B) compound A would bind to the repressor for Gene a.

C) compound B would bind to enzyme A directly.

D) compound A would react with enzyme B directly.

E) compound C would react with gene a

Answer: B

29

29) Conjugation differs from reproduction because conjugation

A) replicates DNA.

B) transfers DNA vertically, to new cells.

C) transfers DNA horizontally, to nearby cells without those cells undergoing replication.

D) transcribes DNA to RNA.

E) copies RNA to make DNA.

Answer: C

30

30) The necessary ingredients for DNA synthesis can be mixed together in a test tube. The DNA polymerase is from Thermus aquaticus, and the template is from a human cell. The DNA synthesized would be most similar to

A) human DNA.

B) aquaticus DNA.

C) a mixture of human and aquaticus DNA.

D) human RNA.

E) aquaticus RNA.

Answer: A

31
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Based on the information in Table 8.3, prostate cancer is probably the result of which kind of mutation?

  1. A) analog
  2. B) frameshift
  3. C) missense
  4. D) nonsense
  5. E) None of the answers is correct.

Answer: D

32
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In Figure 8.4, the antibiotic chloramphenicol binds the 50S large subunit of a ribosome as shown (the light gray area is the large subunit, while the black shape is the drug). From this information you can conclude that chloramphenicol

A) prevents transcription in eukaryotes.

B) prevents translation in eukaryotes.

C) prevents transcription in prokaryotes.

D) prevents translation in prokaryotes.

E) prevents mRNA-ribosome binding.

Answer: D

33

33) The mechanism by which the presence of glucose inhibits the lac operon is

A) catabolite repression.

B) translation.

C) DNA polymerase.

D) repression.

E) induction.

Answer: A

34

34) If you knew the sequence of nucleotides within a gene, which one of the following could you determine with the most accuracy?

A) the primary structure of the protein

B) the secondary structure of the protein

C) the tertiary structure of the protein

D) the quaternary structure of the protein

E) The answer cannot be determined based on the information provided.

Answer: A

35

35) An enzyme that makes covalent bonds between the sugar of one nucleotide and the phosphate groups in another nucleotide in DNA is

A) RNA polymerase.

B) DNA ligase

C) DNA helicase.

D) transposase.

E) DNA polymerase.

Answer: B

36

36) An enzyme that copies DNA to make a molecule of RNA is

A) RNA polymerase.

B) DNA ligase.

C) DNA helicase.

D) transposase.

E) DNA polymerase.

Answer: A

37

37) An enzyme that catalyzes the cutting and resealing of DNA, and is translated from insertion sequences, is

A) RNA polymerase.

B) DNA ligase.

C) DNA helicase.

D) transposase.

E) DNA polymerase.

Answer: D

38

38) Repair of damaged DNA, in some instances and mechanisms, might be viewed as a race between an endonuclease and

A) DNA ligase.

B) DNA polymerase.

C) helicase.

D) methylase.

E) primase.

Answer: D

39

39) The cancer gene ras produces mRNA containing an extra exon that includes a number of UAA codons. Cancer cells produce ras mRNA missing this exon. This mistake most likely is due to a mistake by

A) a chemical mutagen.

B) DNA polymerase.

C) photolyases.

D) snRNPs.

E) UV radiation.

Answer: D

40
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In Figure 8.5, which model of the lac operon correctly shows RNA polymerase, lactose, and repressor protein when the structural genes are being transcribed?

A) a

B) b

C) c

D) d

E) e

Answer: D

41

41) The miRNAs in a cell

A) are found in prokaryotic cells.

B) are a part of the prokaryotic ribosome.

C) are a part of the eukaryotic ribosome.

D) allow different cells to produce different proteins.

E) are responsible for inducing operons.

Answer: D

42

42) Assume the two E.coli strains shown below are allowed to conjugate.

Hfr: pro+, arg+, his+, lys+, met+, ampicillin-sensitive

F-: pro-, arg-, his-, lys-, met-, ampicillin-resistant

What supplements would you add to glucose minimal salts agar to select for a recombinant cell that is lys+, arg+, amp-resistant?

  1. A) ampicillin, lysine, arginine
  2. B) lysine, arginine
  3. C) ampicillin, proline, histidine, methionine
  4. D) proline, histidine, methionine
  5. E) ampicillin, proline, histidine, lysine

Answer: C

43

43) Protein synthesis in eukaryotes is similar to the process in prokaryotes in that both eukaryotes and prokaryotes

A) have exons.

B) have introns.

C) require snRNPS.

D) use methionine as the "start" amino acid.

E) use codons to determine polypeptide sequences.

Answer: E

44

1) Recombination will always alter a cell's genotype.

Answer: TRUE

45

2) Open-reading frames are segments of DNA in which both start and stop codons are found.

Answer: TRUE

46

3) Bacteria typically contain multiple chromosomes.

Answer: FALSE

47

4) Mutations that are harmful to cells occur more frequently than those that benefit cells.

Answer: TRUE

48

5) The miRNAs in a cell inhibit protein synthesis by forming complementary bonds with rRNA.

Answer: FALSE

49

6) Some cells may contain multiple genomes.

Answer: FALSE

50

7) Both base substitution and frameshift mutations can result in the formation of premature stop codons.

Answer: TRUE

51

8) In the Ames test, any colonies that form on the control should be the result of spontaneous mutations.

Answer: TRUE

52

9) Transposition (insertion of a transposon into a DNA sequence) results in the formation of base substitution mutations in a cell's DNA.

Answer: FALSE

53

10) Cell-to-cell contact is required for transduction to occur.

Answer: FALSE