Deck 21: Gene Expression: Ithe Genetic Code and Transcription

Question 1

A change in nucleotide sequence that results in a change to a stop codon is known as a

A)nonsense mutation.
B)silent mutation.
C)missense mutation.
D)frameshift mutation.
E)transversion mutation.

Answer 1

A

Question 2

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

Answer 2

C

Question 3

RNA polymerase recognizes which of the following DNA regions in transcription?

A)promoter
B)operator
C)attenuator
D)leader
E)structural gene

Answer 3

A

Question 4

Which of the following processes is unique to the retroviral information flow within a cell?

A)RNA → protein
B)protein → DNA
C)RNA → DNA
D)DNA → RNA
E)protein → RNA

Question 5

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)ribosome analysis
D)gel electrophoresis
E)RNA sequencing

Question 6

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

Question 7

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

Question 8

Which of the following products are considered final products in the information flow within a cell?

A)DNA
B)RNA
C)protein
D)lipid
E)both choices B and C

Question 9

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

Question 10

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 nonsense mutation has occurred, resulting in a truncated, nonfunctional product in the mutant.
B)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.
C)A missense mutation has occurred, resulting in a truncated, nonfunctional product in the mutant.
D)all of the above
E)Not enough information is given.

Question 11

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

Question 12

According to the central dogma,the process that mediates the conversion of RNA to protein is

A)transduction.
B)translation.
C)transcription.
D)transition.
E)transversion.

Question 13

One reason that prokaryotic genes do not contain introns is that

A)the introns are cut out during binary fission.
B)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.
C)bacterial proteins are very short and not subject to mutation.
D)translation sometimes begins before transcription has been completed because prokaryotes do not have a nucleus.
E)integrated viral DNA is not recognized for transcription.

Question 14

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

Question 15

In a eukaryotic cell,a gene that is initially transcribed is 1500 nucleotides in length.The mature mRNA for the product is 1200 nucleotides in length.What is the most probable reason for the discrepancy?

A)a mutation that results in a shorter product
B)removal of introns
C)removal of exons
D)mRNA breakage
E)both choices A and D

Question 16

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

Question 17

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

Question 18

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

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

Question 19

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

Question 20

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

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

Question 21

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

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

Question 22

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

Question 23

RNA polymerase II differs from RNA polymerase I and III by having

A)fewer amino acids at the N-terminus.
B)additional amino acids at the N-terminus.
C)fewer amino acids at the C-terminus.
D)additional amino acids at the C-terminus.
E)individual amino acids, but all three RNA polymerases are the same size.

Question 24

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

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

Question 25

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

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

Question 26

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

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

Question 27

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

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

Question 28

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

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

Question 29

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

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

Question 30

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

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

Question 31

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

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

Question 32

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

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

Question 33

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

Question 34

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

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

Question 35

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 choices A and B

Question 36

The DNA technique used to initially identity promoter sequences was

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

Question 37

Transcription of ribosomal RNA is primarily the function of

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

Question 38

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

Question 39

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

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

Question 40

Which of the following enzymes is responsible for specifically transcribing tRNA in eukaryotic cells?

A)RNA polymerase I
B)RNA polymerase II
C)RNA polymerase III
D)primase
E)RNase H

Question 41

________ are nonviral genetic elements that have reverse transcriptase activity.

Question 42

You are trying to discover what novel proteins are expressed by a T cell line in response to interaction with a novel antigen associated with HIV.As this is a potential vaccine candidate,you need to see what features of the immune response are initiated by T cells.How would you go about the task?

Question 43

________-driven promoters do not contain TATA boxes or BREs.

Question 44

The ________ activity of RNA polymerase is sufficient for the process of RNA proofreading.

Question 45

Explain how an electrophoretic mobility shift assay (EMSA)works.How might one use this technique?

Question 46

You are interested in the novel expression of novel products that are transcribed in response to viral infection by respiratory epithelial cells.How would you go about specifically isolating mRNA in order to begin the process of answering your question? How would this differ if you were using a bacterial model?

Question 47

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

Question 48

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

Question 49

________-driven promoters are comprised of an Inr sequence and a TATA box with or without an associated BRE.

Question 50

A ________ is a complex of RNA and protein that serves to remove introns from pre-mRNA.

Question 51

In eukaryotic transcription,TFIID recognizes and binds the ________ box in the DNA.

Question 52

A mutation that results in the addition or deletion of a single nucleotide that radically changes the amino acid sequence of the resulting polypeptide is known as a ________ mutation.

Question 53

One of the NASA land rovers returns from its mission with a variety of samples.From one,a unique bacterial species has been isolated and cultured.Your job is to investigate whether or not the genetic code is overlapping or nonoverlapping.Another researcher has discovered that rather than a codon of three nucleotides,this organism uses groups of four nucleotides.Show how you would verify the presence of overlapping versus nonoverlapping frames when you thought the codon was read in groups of three nucleotides and in groups of four nucleotides.How would your data have been different without the knowledge of codons as groups of four nucleotides?
Test mRNA sequence: 5'-AUUGGCCAAUUUACGGUAAUGGCCAAUUUACGGU-3'

Question 54

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

Question 55

The coding regions of a gene are known as ________.

Question 56

You have identified a protein that you feel is a sigma factor in E.coli that has not yet been characterized to date.Design an experiment whereby use can determine that this factor is a sigma factor.

Question 57

The 21st and 22nd amino acids found in proteins are the rare amino acids ________ and ________.

Question 58

In order to protect the integrity of an mRNA in the cytosol of a cell,a(n)________ is added to the 3' end during RNA processing.