Deck 18: Gene Expression: Ithe Genetic Code and Transcription

Question 1

You are studying a eukaryotic gene whose initial transcript is 1500 nucleotides in length.The mature mRNA derived from the gene 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)A mutation that results in a shorter product or mRNA breakage could have occurred.

Answer 1

B

Question 2

Which of the following molecules can be considered a final product in the flow of information within a cell?

A)DNA
B)RNA
C)protein
D)lipid
E)Protein or RNA can be the final product of a gene.

Answer 2

E

Question 3

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.

Answer 3

A

Question 4

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)inhibit the viral reverse transcriptase.
B)inhibit retro-RNA polymerase.
C)inhibit polyadenine removal.
D)inhibit the viral reverse transcriptase and polyadenine removal.
E)None of these are good antiretroviral strategies.

Question 5

One consequence of the lack of introns in bacterial genes is that

A)exons are eliminated during transcription.
B)a 5' cap and poly (A)tail can be added immediately.
C)bacterial proteins are very short and not subject to mutation.
D)translation can begins before transcription is complete because prokaryotes do not have a nucleus.
E)integrated viral DNA is not recognized for transcription.

Question 6

Answer the questions below based on this RNA sequences: 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 codon is a different amino acid


-Imagine that the genetic code were read in an overlapping fashion,using three nucleotides to specify each amino acid (i.e.,the sequence above would be read: AUG-UGA-GUA and so on).Which of the following polypeptides would be obtained by translating the sequence above?

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.

Question 7

Which of the following DNA regions is recognized by RNA polymerase during transcription?

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

Question 8

Which of the following is not a true statement regarding the genetic code?

A)The genetic code is degenerate.
B)The genetic code is nearly universal,with only a few minor exceptions.
C)The genetic code is nonoverlapping.
D)The genetic code is triplet-based.
E)Each codon represents a different amino acid.

Question 9

Answer the questions below based on this RNA sequences: 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 codon is a different amino acid


-Imagine that the genetic code were read in a non-overlapping fashion,using only two nucleotides to specify an amino acid (i.e.,the sequence above would be read: AU-GA-UG and so on).Which of the following polypeptides would be obtained by translating the sequence above?

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 10

Answer the questions below based on this RNA sequences: 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 codon is a different amino acid


-Imagine that the genetic code were read in a non-overlapping fashion,using four nucleotides to specify each amino acid (i.e.,the sequence above would be read: AUGA-UGAU-GUAG).Which of the following polypeptides would be obtained by translating the sequence above?

A)B-B-B.
B)B-D-B.
C)B-D-E.
D)D-D-D.
E)None of these is correct.

Question 11

Which of the following amino acids is not one of the 20 common amino acids found in cells?

A)leucine
B)isoleucine
C)glutamine
D)proline
E)pyrrolysine

Question 12

In eukaryotic cells,we sometimes find reverse transcriptase activity,even though the cells are not infected with a retrovirus.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 13

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 14

According to the central dogma,the process by which information in an RNA molecule is used to direct the synthesis of a polypeptide is called

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

Question 15

Which of the following enzymes is required in order to produce DNA molecules complementary to mRNA transcripts?

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

Question 16

Which of the following patterns of information flow is unique to retroviruses within a cell?

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

Question 17

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

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

Question 18

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
E)removal of exons and introns

Question 19

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 20

Consider the following double-stranded DNA sequence that codes for a short polypeptide. 5'-A-T-G-T-G-G-C-C-A-C-T-A-T-A-A-T-C-A-3'
3'-T-A-C-A-C-C-G-G-T-G-A-T-A-T-T-A-C-T-5'
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 to answer the question.

Question 21

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

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

Question 22

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

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

Question 23

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

A)RNA processing 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 in tRNA transcripts.

Question 24

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 prokaryotic promoter by RNA polymerase
C)DNase activity
D)RNA polymerase II activity
E)ribosomal binding to mRNA

Question 25

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 26

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

Question 27

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

A)RNA backtracking can remove noncomplementary nucleotides.
B)RNA and DNA polymerase proofreading are essentially identical.
C)There are specialized mRNA repair pathways that remove noncomplementary nucleotides.
D)No proofreading occurs.
E)A 3' → 5' exonuclease fixes all errors in mRNA.

Question 28

You have isolated a piece of DNA that you believe contains an interesting gene.Using a mix of RNA polymerase and ribonucleotides,you perform in vitro transcription.However,even though all of your controls work,no mRNA is created from your DNA fragment.Working backward,you note that your DNA preparation removed approximately 250 base pairs from the 5' end of the gene.The most likely explanation is that during DNA preparation

A)the termination signal was removed.
B)the RNA polymerase became inactivated.
C)the 5' methyl guanosine cap was removed.
D)the promoter was removed.
E)None of these explains the negative results.

Question 29

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

Question 30

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

A)promoters
B)transcription factors
C)retrotransposons
D)prions
E)None of these are correct.

Question 31

Which of the following most accurately describes the flow of information for retroviruses?

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

Question 32

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)either transcription termination signals or spliceosome activity.

Question 33

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

Question 34

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

A)leucine.
B)arginine.
C)isoleucine.
D)selenocysteine.
E)cysteine.

Question 35

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 36

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

A)methionine.
B)cysteine.
C)glycine.
D)pyrrolysine.
E)None of these.

Question 37

The coding regions of a eukaryotic gene are known as ________.

Question 38

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 39

Which of the following 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 spliceosome mutations and polycistronic organization

Question 40

The 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 41

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

Question 42

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

Question 43

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

Question 44

RNA has many functions in a cell.Besides mRNA,which carries information from the genome to the translation machinery,and rRNA,which is part of ribosomes and catalyzes the formation of peptide bonds,name three other types of RNA and describe the function of each.

Question 45

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

Question 46

RNA proofreading is ________ stringent than DNA proofreading.

Question 47

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

Question 48

You have identified a protein that you hypothesize is a sigma factor in E.coli that has not yet been characterized.You have purified the protein.What types of experiments could you perform to investigate whether or not the protein is a sigma factor?

Question 49

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

Question 50

One of the NASA rovers returns from its mission with a variety of samples.From one sample the rover has isolated and cultured a unique prokaryotic species that contains many novel amino acids,causing scientists to hypothesize that the genetic code may be different in this organism.Your job is to investigate whether or not the genetic code uses overlapping or non-overlapping codons.Another researcher has data suggesting that rather than codons of three nucleotides,this organism uses groups of four nucleotides.Show how you would verify the presence of overlapping versus non-overlapping codon frames and how you could tell if the codons use three or four nucleotides.Use the following test mRNA sequence in your experiment.
Test mRNA sequence: 5'-AUUGGCCAAUUUACGGUAAUGGCCAAUUUACGGU-3'

Question 51

________ are nonviral genetic elements that have reverse transcriptase activity.

Question 52

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

Question 53

You are interested in a eukaryotic protein involved in immunity,and you are attempting to express this protein in E.coli in order to produce large amounts of the protein.You have identified the gene and place a copy of the gene on a plasmid in E.coli next to a bacterial promoter sequence.You determine that lots of mRNA is made from your gene in your E.coli system,but the protein produced is larger and doesn't have the same properties as the eukaryotic protein you expected.What mistake have you made and how can you fix it?

Question 54

When evolutionary biologists examine DNA sequences of protein-coding genes,they observe that every third nucleotide changes more rapidly over time compare to other nucleotides.Based on the properties of the genetic code,why might this occur?