Practice Quiz 10

Question 1

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

2.	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.

Answer 2

B

Question 3

3. 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.

Answer 3

B

Question 4

4. 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.

Answer 4

E

Question 5

5.	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 5

A

Question 6

6.	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

Answer 6

A

Question 7

7.	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

Answer 7

C

Question 8

8. 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.

Answer 8

D

Question 9

9.	Which of the following DNA regions is recognized by RNA polymerase during transcription?
A)	promoter
B)	operator
C)	attenuator
D)	leader
E)	structural gene

Answer 9

A

Question 10

10.	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

Answer 10

c

Question 11

11.	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.

Answer 11

b

Question 12

12. 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

Answer 12

b

Question 13

13. 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.

Answer 13

d

Question 14

14. 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

Answer 14

a

Question 15

15.	In which of the following groups are most mRNAs monocistronic?
A)	bacteria
B)	archaea
C)	eukarya
D)	bacteria and archaea
E)	All mRNAs are monocistronic.

Answer 15

c

Question 16

16. In eukaryotic initiation, one will often see the sequence ACCAUGG as a translational start sequence. This sequence is known as the ________ sequence.
    A) Okazaki
    B) ETS (eukaryotic translational start)
    C) Kozak
    D) IRES (internal ribosome entry sequence)
    E) CIBS (complex initiation binding sequence)

Answer 16

c

Question 17

17. In eukaryotes, the 3ʹ end of the mRNA is important in the initiation of translation because
    A) it contains Kozak sequences that aid in initiation.
    B) translation occurs in the 3ʹ to 5ʹ direction.
    C) eIF4A is attached to the 3ʹ end and removes any secondary structure that might prevent translation.
    D) the 3ʹ poly(A) tail and PABP bind initiation factor eIF4G, stabilizing the 5ʹ end of the mRNA.
    E) it contains Kozak sequences that aid in initiation of translation in the 3ʹ to 5ʹ direction.

Answer 17

d

Question 18

18. Using the techniques of genetic engineering, you design a protein you want to accumulate within the ER of yeast cells. To accomplish this goal, you need to
    A) do nothing; all proteins go through the ER.
    B) incorporate appropriate mannose-6-phosphate groups.
    C) incorporate the appropriate DNA sequence(s) to create signal sequences in the mature peptide.
    D) incorporate radioactive amino acids into the protein.
    E) remove the N-formyl group located at the N-terminus of the polypeptide.

Answer 18

c

Question 19

19.	Which of the following activities is not associated with post-translational processing? 
A)	glycosylation 
B)	specific cleavage of polypeptides 
C)	chaperonin activity 
D)	addition of lipid groups 
E)	polyadenylation

Answer 19

e

Question 20

20. AUG is the “start” codon in
    A) prokaryotic translation.
    B) eukaryotic translation.
    C) both prokaryotic and eukaryotic translation.
    D) neither prokaryotic nor eukaryotic translation.
    E) prokaryotic modification.

Answer 20

c

Question 21

21. The initial amino acid incorporated into a nascent peptide is N-formylated in
    A) eukaryotic translation.
    B) prokaryotic transcription.
    C) prokaryotic translation.
    D) both eukaryotic and prokaryotic translation.
    E) both transcription and translation in prokaryotes.

Answer 21

c

Question 22

22.	Shine–Dalgarno sequences are present in mRNAs of 
A)	prokaryotes. 
B)	eukaryotes. 
C)	humans. 
D)	plants. 
E)	both prokaryotes and eukaryotes.

Answer 22

a

Question 23

23.	The mRNA is translated in the 3ʹ to 5ʹ direction in 
A)	bacteria. 
B)	eukaryotes. 
C)	archaea. 
D)	eukaryotes, bacteria, and archaea. 
E)	None of these.

Answer 23

e

Question 24

24.	Polycistronic mRNAs encode 
A)	one product that is alternatively spliced. 
B)	more than one protein. 
C)	multiple cis elements. 
D)	exclusively eukaryotic proteins. 
E)	None of these.

Answer 24

b

Question 25

25. You are examining a bacterial enzyme associated with glycolysis. You would expect expression of the enzyme to be
    A) amplified when glucose is depleted.
    B) induced by glucose.
    C) repressed by glucose.
    D) induced when ATP concentrations in the cell are high.
    E) controlled by a riboswitch.

Answer 25

b

Question 26

27.	Which of the following processes is/are associated with the modification of histone proteins in vivo?
A)	acetylation
B)	alkylation
C)	methylation
D)	transhydroxylation
E)	acetylation and methylation

Answer 26

e

Question 27

28.	The situation in which an active regulatory protein "turns on" gene expression is an example of 
A)	feedback inhibition. 
B)	positive control. 
C)	negative control. 
D)	constitutive gene elements. 
E)	a mutation.

Answer 27

b

Question 28

29.	The situation in which an active regulatory protein "turns off" gene expression is an example of 
A)	a mutation. 
B)	positive control. 
C)	negative control. 
D)	constitutive gene elements. 
E)	unique regulation.

Answer 28

c

Question 29

30.	Which of the following is an example of translational regulation? 
A)	protein degradation 
B)	DNA splicing 
C)	protein folding 
D)	mRNA degradation 
E)	DNA methylation

Answer 29

d

Question 30

31. Sigma (σ) factors can regulate the initiation of transcription. Which of the following is not an example of σ regulation?
    A) Some σ factors recognize promoters for genes whose products are necessary when the organism is under stress, such as heat shock.
    B) Some σ factors recognize promoters for genes whose products are necessary for nitrogen utilization.
    C) Bacteriophages may code for specific σ factors that bind the core RNA polymerase and result in recognition of viral promoters.
    D) Many σ factors regulate genes associated with embryonic development in eukaryotes.
    E) UV irradiation can trigger the use of alternative σ factors.

Answer 30

d

Question 31

32. Gene knockdown via RNAi relies on the ability of eukaryotic cells to
    A) degrade target mRNAs that are complementary to introduced dsRNA.
    B) induce microRNA expression under particular conditions.
    C) preferentially degrade mutated mRNAs.
    D) inhibit transcription of sets of genes based on the presence of distal control elements.
    E) preferentially degrade mutated mRNAs by inducing microRNA expression under particular conditions.

Answer 31

a

Question 32

26. You are examining an enzyme associated with cysteine biosynthesis. You would expect expression of the enzyme to be
    A) amplified when cysteine concentrations are high.
    B) induced by cysteine.
    C) repressed by cysteine.
    D) high when ATP concentrations in the cell are low.
    E) controlled by a riboswitch.

Answer 32

c

Question 33

33.	Genes that are always "turned on" in a cell are referred to as 
A)	regulated genes. 
B)	mutations. 
C)	inducible. 
D)	constitutive. 
E)	catabolic.

Answer 33

d

Question 34

34.	Genes that are expressed only when needed are
A)	unregulated.
B)	mutations.
C)	inducible.
D)	constitutive.
E)	anabolic.

Answer 34

c

Question 35

35. You are working with a gene associated with an essential pathway that is necessary at two time points in an organism’s lifetime. With regard to gene regulation, you would expect the gene to be
    A) constitutive.
    B) associated with response to distinct events.
    C) induced by particular signals.
    D) repressed by particular signals.
    E) associated with response to distinct events through induction and repression signals.

Answer 35

e

Question 36

36.	In eukaryotic cells, which of the following genetic elements can prevent the increase in gene expression that results from the presence of an enhancer sequence?
A)	repressor
B)	silencer
C)	cofactor
D)	insulator
E)	sigma factor

Answer 36

d

Question 37

37. Within a genome, an enhancer may be located
    A) upstream of the gene enhanced.
    B) downstream of the gene enhanced.
    C) within the introns of other genes.
    D) proximal to the gene enhanced.
    E) upstream or downstream of the gene enhanced, even within the introns of other genes.

Answer 37

e

Question 38

38. Within a genome, an enhancer may be located
    A) upstream of the gene enhanced.
    B) downstream of the gene enhanced.
    C) within the introns of other genes.
    D) proximal to the gene enhanced.
    E) upstream or downstream of the gene enhanced, even within the introns of other genes.

Answer 38

e