Deck 21: Gene Expression: I the Genetic Code and Transcription

Question 1

An agent that would work well as an antibiotic against prokaryotic infection would target the

A)DNA polymerase.
B)mitochondria.
C)50S large ribosomal subunit.
D)RNA polymerase II.
E)40S small ribosomal subunit.

Answer 1

C

Question 2

In the process of isolating DNA for transcription and translation, you digest the DNA with BamHI and ligate the gene into a plasmid vector. However, even though all of the controls work, no transcription is obtained using your fragment. Working backward, you note that restriction digestion has removed approximately 250 base pairs from the 5' end of the gene. It is possible that during restriction digestion

A)the promoter was removed.
B)the RNA polymerase became inactivated.
C)the termination signal was removed.
D)primase could not bind.
E)none of the above

Answer 2

A

Question 3

In eukaryotic cells, we sometimes find reverse transcriptase activity, even though the cells are not infected with virus. This activity can be attributed to

A)infection with small bacteria known as mycoplasmas.
B)a novel prion infection.
C)the presence of viroids.
D)the presence of transposons integrating into polymerase genes.
E)the presence of retrotransposons.

Answer 3

E

Question 4

You expect that a mutation in E. coli that was recently isolated results in loss of enzyme R activity. In looking for the gene you find comparable sequences. Using an in vitro transcription translation system, you use the gene obtained from the mutant as well as a wild type E. coli as a control. Following protein isolation and gel electrophoresis, you observe that the wild type E. coli produces a protein that is 35K in size, corresponding to enzyme R. However, the mutant strain produces a protein that is 25K in size. What does this information suggest?

A)A missense mutation has occurred, resulting in a truncated, nonfunctional product in the mutant.
B)A nonsense mutation has occurred, resulting in a truncated, nonfunctional product in the mutant.
C)A large addition has occurred in the wild type strain, such that approximately 35 tandem repeats of this gene are present and are biologically active.
D)all of the above
E)Not enough information is given.

Question 5

Answer the questions below based on this diagram: 5'- AUGAUGAUGAUG- 3'
This RNA transcript was generated using a synthetic DNA template. The letters B, D, E, F, G, and H have been selected to represent different amino acids. Assume that each different group of codons is a different amino acid.
If the genetic code were read in groups of four nonoverlapping nucleotides, using this nucleotide sequence, then the resulting amino acid sequence would be

A)B- D- B.
B)B- B- B.
C)D- D- D.
D)B- D- E.
E)none of the above

Question 6

Of the following, which is associated with the production of multiple mRNAs from a single gene?

A)alternative splicing
B)gene rearrangement
C)polycistronic organization
D)splicesome mutations
E)both B and C

Question 7

The action of a new drug is unknown, so you test various aspects of eukaryotic cell processes looking for an effect. You notice that the survival of cells exposed to this drug is very low. Further analysis shows that some proteins and mRNAs are much longer than they should be. One hypothesis is that the drug interferes with

A)transcription termination signals.
B)spliceosome activity.
C)ribosomes.
D)nucleoli.
E)both A and B

Question 8

A change in a single nucleotide that results in no change in the amino acid sequence of the polypeptide produced is known as a

A)nonsense mutation.
B)frameshift mutation.
C)missense mutation.
D)silent mutation.
E)none of the above

Question 9

An individual has been infected with a particular retrovirus. In order for the latent virus DNA to be inherited by subsequent generations stemming from this individual, it must be found

A)in somatic cells.
B)in all cells simultaneously.
C)in germ line cells.
D)in stem cells.
E)at a point early in childhood.

Question 10

With respect to RNA processing, which of the following is false?

A)Some introns are self- splicing.
B)Some introns are removed by spliceosomes.
C)It leads to the production of alternative gene products.
D)Chemical modification occurs with tRNA transcripts.
E)Prokaryotic mRNAs are polyadenylated at the 3' end.

Question 11

Which of the following is NOT a reason for the importance of mRNA processing in eukaryotes?

A)coupling of transcription and translation
B)removal of introns
C)longevity in the cytoplasm
D)turnover in the cytoplasm
E)presence of a nuclear membrane

Question 12

A change in a nucleotide sequence that results in addition or deletion of a single nucleotide and largely changes the amino acid sequence of the resulting peptide is known as a

A)silent mutation.
B)nonsense mutation.
C)frameshift mutation.
D)missense mutation.
E)none of the above

Question 13

Answer the questions below based on this diagram: 5'- AUGAUGAUGAUG- 3'
This RNA transcript was generated using a synthetic DNA template. The letters B, D, E, F, G, and H have been selected to represent different amino acids. Assume that each different group of codons is a different amino acid.
If the genetic code required only two nucleotides for incorporation of amino acids, the amino acid sequence using this transcript would be

A)B- B- B- D- D- D.
B)B- D- E- B- D- E.
C)B- B- B- B- B- B.
D)B- D- E- F- G- H.
E)B- D- B- D- B- D.

Question 14

The human immunodeficiency virus (HIV)is an example of a retrovirus. In order to prevent incorporation of the viral DNA into the host genome, antiretroviral drugs could

A)activate high levels of DNase in the cells to break down the viral DNA while it is still in the cytosol.
B)target the viral enzyme reverse transcriptase.
C)target the viral enzyme integrase.
D)all of the above
E)none of the above

Question 15

Which of the following is NOT associated with mRNA processing in eukaryotes?

A)addition of a 5' methyl guanosine cap
B)removal of exons
C)3' polyadenylation
D)removal of introns

Question 16

The "central dogma" of retroviruses is most accurately described as

A)DNA -protein.
B)DNA -RNA -protein.
C)protein -RNA -DNA -protein.
D)RNA -DNA -RNA -protein.
E)RNA -protein.

Question 17

If you were designing a method to specifically inhibit prokaryotic transcription, but not eukaryotic transcription, interfering with which of the following would work best?

A)RNA polymerase II activity
B)ribosomal binding
C)an intercalating agent
D)DNase activity
E)recognition of the promoter region

Question 18

In the absence of retroviruses, eukaryotes may also undergo reverse transcription if which of the following is present?

A)prions
B)Alu
C)retrograde viruses
D)retrotransposons
E)none of the above

Question 19

A new antibiotic is able to bind the rho (q)factor associated with some transcription processes; as a result this antibiotic would affect

A)termination of all transcription.
B)initiation of transcription.
C)binding of the RNA polymerase.
D)termination of some transcription.
E)elongation of transcription.

Question 20

Which of the following enzymes is associated with "transcription factories" in the nuclease?

A)transcriptomes
B)reverse transciptase
C)RNA polymerase I
D)RNA polymerase II
E)DNA polymerase III

Question 21

In some organisms, a normal stop codon, UGA, encodes for the amino acid .

A)isoleucine
B)leucine
C)selenocysteine
D)pyrrolysine
E)arginine

Question 22

The technique initially used in the identification of promoter sequences was .

Question 23

The DNA technique used to initially identity promoter sequences was

A)chromatin immunoprecipitation assay.
B)chromosomal walking.
C)DNA footprinting.
D)DNA fingerprinting.
E)RNA protection.

Question 24

Transcription of ribosomal RNA is primarily the function of

A)primase.
B)RNA polymerase II.
C)RNA polymerase III.
D)mitochondrial RNA polymerase.
E)RNA polymerase I.

Question 25

In some organisms, a special tRNA recognizes the UAG stop codon, but incorporates the amino acid

A)selenocysteine.
B)pyrrolysine.
C)methionine.
D)glycine.
E)none of the above.

Question 26

Which of the following is NOT a feature of the genetic code?

A)universal, with rare exception
B)degenerate
C)triplet code
D)each codon represents a different amino acid
E)nonoverlapping

Question 27

A more contemporary technique for identification of promoter sequences is the assay.

Question 28

Examine the following double- stranded DNA sequence: A- T- G- T- G- G- C- C- A- C- T- A- T- A- A- T- G- A T- A- C- A- C- C- G- G- T- G- A- T- A- T- T- A- C- T Which strand is the coding strand, and where is the N- terminal end of the resulting peptide located?

A)The bottom strand is the coding strand, and the N- terminus is on the left.
B)The top strand is the coding strand, and the N- terminus is on the right.
C)The bottom strand is the coding strand, and the N- terminus is on the right.
D)The top strand is the coding strand, and the N- terminus is on the left.
E)Not enough information is given.

Question 29

Answer the questions below based on this diagram: 5'- AUGAUGAUGAUG- 3'
This RNA transcript was generated using a synthetic DNA template. The letters B, D, E, F, G, and H have been selected to represent different amino acids. Assume that each different group of codons is a different amino acid.
If you know the order of the nucleotides in a certain gene, what is the best way to determine which reading frame method is actually being used in a particular organism?

A)protein sequencing
B)DNA sequencing
C)RNA sequencing
D)ribosome analysis
E)gel electrophoresis

Question 30

An example of a retrovirus in the human genome is the family of sequences.

Question 31

Answer the questions below based on this diagram: 5'- AUGAUGAUGAUG- 3'
This RNA transcript was generated using a synthetic DNA template. The letters B, D, E, F, G, and H have been selected to represent different amino acids. Assume that each different group of codons is a different amino acid.
If the genetic code were overlapping by one nucleotide, using three nucleotides to encode an amino acid, then the resulting amino acid sequence using this sequence would be

A)B- D- E- B- D- E- B- D- E- B.
B)B- D- E- F- B- B- D- E- F- B.
C)B- D- B- D- B- D- B- D- B- D.
D)B- B- B- B- B- B- B- B- B- B.
E)B- D- E- F- G- B- D- E- F- G.

Question 32

With regard to RNA polymerase proofreading ability, which of the following is CORRECT?

A)There are specialized mRNA repair pathways that fix errors.
B)It is similar to that of DNA polymerases.
C)The 3' -5' exonuclease activity is sufficient.
D)It is a very stringent activity, no tolerance for mistakes.
E)There is absolutely no proofreading that needs to be done.

Question 33

The coding regions of a gene are known as .

Question 34

In order to examine mRNA transcripts isolated from cells, one needs to convert a RNA template to DNA. Doing this conversion requires which of the following enzymes?

A)RNA polymerase
B)reverse transcriptase
C)DNA polymerase
D)DNA transcriptase
E)reverse convertase

Question 35

One reason that prokaryotic genes do not contain introns is that

A)integrated viral DNA is not recognized for transcription.
B)the introns are cut out during binary fission.
C)due to the short time the bacterium is around as a single organism, a 5' cap and poly A tail are added immediately for translation to take place.
D)as prokaryotes do not have a nucleus, translation sometimes begins before transcription has been completed.
E)bacterial proteins are very short and not subject to mutation.

Question 36

- driven promoters do not contain TATA boxes or BREs.

Question 37

You are wishing to design a drug that acts against a recently identified retrovirus. Based upon what you know about retroviruses, which of the following would be the best target for specifically interrupting the viral life cycle in eukaryotic cells?

A)DNA polymerase
B)primase
C)30S ribosomal subunits
D)reverse transcriptase
E)RNA polymerase