Deck 6: DNA, RNA, and Protein Synthesis

Question 1

In a particular bacterial operon, there are two genes that are transcribed into one mRNA transcript.In order, how many promoter regions, how many ribosomal binding sites, how many AUG initiation codons, and how many stop codons do you expect to find in the operon or its mRNA?

A)2, 2, 2, 2.
B)2, 1, 1, 1.
C)2, 2, 2, 1.
D)1, 1, 1, 1.
E)1, 2, 2, 2.

Answer 1

1, 2, 2, 2.

Question 2

In Figure 6.5, the strand labeled B is the:

A)Leading strand.
B)Lagging strand.
C)Okazaki fragment.
D)Template strand.
E)RNA primer.

Answer 2

Leading strand.

Question 3

Figure 6.5 is a diagram of DNA replication at a replication fork. The black boxes labeled D and E are:

A)DNA template strands.
B)Okazaki fragments.
C)DNA polymerase.
D)RNA primers.
E)Newly synthesized DNA strands.

Answer 3

RNA primers.

Question 4

The following mutation occurred near the 5' end of the coding sequence.The sequence shown is the coding strand of the gene.It includes the start codon and the mutation.G A T T C A T G T T C G G A C T G G T G T A T
G A T T C A T G T T C G G A C T G T A T
What is the consequence of this mutation?

A)The amino end of the encoded protein is normal, but the sequence between the site of the mutation and the C terminus is completely abnormal.
B)A single amino acid is missing in the sequence.
C)A single amino acid is replaced by another amino acid.
D)This is a nonsense mutation that results in premature chain termination.
E)Splicing of the transcript is abnormal.

Question 5

Inhibitors of DNA replication are most likely to find medical use as:

A)Antifungal agents.
B)Treatments for immunodeficiency diseases.
C)Antibiotics.
D)Anticancer drugs.
E)Treatments for psychiatric conditions such as schizophrenia.

Question 6

Many antibiotics inhibit the growth of bacteria by blocking their protein synthesis.The broad-spectrum antibiotic tetracycline inhibits:

A)Translocation.
B)Reading of mRNA.
C)Peptide bond formation.
D)Transcription.
E)Aminoacyl-tRNA binding.

Question 7

Mutations are hazardous to the health of E.coli (and Homo sapiens as well).To reduce this health hazard, E.coli employs:

A)The 3' --> 5' endonuclease activity of DNA polymerase I.
B)The 5' --> 3' exonuclease activity of DNA polymerase III.
C)The 3' --> 5' exonuclease activity of DNA polymerase III.
D)The 3'--> 5' exonuclease activity of DNA polymerase II.
E)The 5' --> 3' endonuclease activity of DNA polymerase I.

Question 8

Which of the following is a true statement about repressor proteins?

A)In most cases, they bind the DNA in a dimeric or oligomeric form.
B)They do not have allosteric properties.
C)They bind to a regulatory gene.
D)They are produced by the operator site.
E)They bind to a site near the promoter that does not overlap with the binding site for RNA polymerase.

Question 9

During DNA replication, the many RNA primers found in the lagging strand must be removed.Which enzyme performs this task in E.coli?

A)RNAse A.
B)Helicase.
C)RNA polymerase II.
D)DNA polymerase I.
E)DNA polymerase III.

Question 10

Translation is terminated by a release factor (RF) and:

A)Rho.
B)A stem-loop structure.
C)UGA, UAG, or UAA codons.
D)AUG codons.
E)Consecutive trp codons.

Question 11

Where is the regulation of gene expression most likely to occur?

A)At initiation of translation.
B)Post-translationally.
C)At initiation of DNA replication.
D)At termination of transcription.
E)At initiation of transcription.

Question 12

Which of the following components is a cytoplasmic protein that transiently associates with the ribosome?

A)Shine-Dalgarno sequence.
B)The catabolite activator protein (CAP).
C)Elongation factor G.
D)Peptidyl transferase.
E)Aminoacyl-tRNA synthetase.

Question 13

Unlike DNA polymerases, RNA polymerases:

A)Can elongate a primer oligonucleotide.
B)Can initiate synthesis of their polynucleotide product.
C)Generate inorganic pyrophosphate.
D)Have 3'-exonuclease activity.
E)Require a separate helicase enzyme for strand separation before they can start synthesizing their product.

Question 14

The purpose of the gene products of the lac operon is to ___________.The purpose of the gene products of the trp operon is to ___________.

A)Produce lactose when glucose is low; produce tryptophan when tryptophan is low.
B)Produce lactose when lactose is low; produce tryptophan when glucose is low.
C)Produce lactose when glucose is low; metabolize tryptophan for energy.
D)Metabolize lactose when glucose is low; metabolize tryptophan for energy.
E)Metabolize lactose when glucose is low; produce tryptophan when tryptophan is low.

Question 15

With what messenger RNA (mRNA) codon would the transfer RNA (tRNA) in the diagram be able to form a codon-anticodon base pairing interaction?

A)5'-AUG-3'.
B)5'-GUA-3'.
C)5'-UAC-3'.
D)5'-CAU-3'.
E)5'-GAU-3'.

Question 16

Which of the radiolabeled oligonucleotide probes below would best hybridize with the DNA sequence 5'-AAAAGGTTCC-3'?

A)32P-5'-CCTTGGAAAA-3'.
B)32P-5'-AAAAGGTTCC-3'.
C)32P-5'-TTTTCCAAGG-3'.
D)32P-5'-GGAACCTTTT-3'.
E)32P-5'-UUUUCCAAGG-3'.

Question 17

The lac operon is induced by the presence of lactose, but it is transcribed at a high rate only when:

A)The cyclic adenosine monophosphate (cAMP) level in the cell is high.
B)A ribosome binds to the Shine-Dalgarno sequence.
C)A ribosome binds to the 5' cap of the mRNA.
D)Tryptophan is present in high concentration.
E)Glucose is present

Question 18

A promoter region of a gene is best described as:

A)A purine-rich sequence downstream from the start site of transcription.
B)A ribosome-binding site on the mRNA.
C)A site where RNA polymerases bind to DNA to initiate transcription.
D)A site where repressors bind to RNA polymerase to terminate transcription.
E)The first transcribed segment of the gene.

Question 19

Which of the following bases, when it occurs in the wobble position in tRNA, can bind to three different bases (adenine [A], uracil [U], and cytosine [C])?

A)Cytosine.
B)Hypoxanthine.
C)Adenine.
D)Guanine.
E)Uracil.

Question 20

Figure 6.3 is a diagram of DNA replication at a replication fork. The strand labeled C is:

A)The template strand.
B)The leading strand.
C)The RNA primer.
D)The lagging strand.
E)The Holliday intermediate.

Question 21

Which of the following does not have an ATP or GTP requirement?

A)Attachment of an amino acid to its tRNA.
B)Placement of a new aminoacyl-tRNA on the ribosome during elongation.
C)Movement of the ribosome along the mRNA.
D)Formation of the peptide bond during protein synthesis.
E)Assembly of the translational initiation complex.

Question 22

Under conditions in which methionine must be the first amino acid, what protein would be coded for by the following mRNA? 5'-CCUCAUAUGCGCCAUUAUAAGUGACACACA-3'

A)Pro-His-Met-Arg-His-Tyr-Lys-Cys-His-Thr.
B)Met-Arg-His-Tyr-Lys-Cys-His-Thr.
C)Met-Arg-His-Tyr-Lys.
D)Met-Pro-His-Met-Arg-His-Tyr-Lys-Cys-His-Thr.
E)Arg-His-Ser-Glu-Tyr-Tyr-Arg-Leu-Tyr-Ser.

Question 23

Which of the following correctly describes the structure of the DNA double helix?

A)The bases are in the center of the double helix and do not contact the surrounding water.
B)2-Deoxyribose forms O-glycosidic bonds.
C)All hydroxyl groups of 2-deoxyribose are tied up in covalent bonds.
D)The purine and pyrimidine bases carry positive charges at a pH of 7.
E)The double helix can interact with proteins mainly through hydrophobic interactions.

Question 24

The consensus sequences of prokaryotic promoters are recognized by:

A)RNA polymerase core enzyme.
B)The TATA-binding protein.
C)The β´ subunit of RNA polymerase.
D)The σ subunit of RNA polymerase.
E)Small nuclear ribonucleoprotein particles.

Question 25

During DNA replication, which type of enzyme separates double-stranded DNA into the single-stranded DNA that is needed as a template for the DNA polymerases?

A)DNase.
B)Topoisomerase.
C)Helicase.
D)Primase.
E)Single-stranded DNA binding (SSB) protein.