20 Questions Molecular Biology Quiz with Answers

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1. RNA polymerase can proofread by using its active site in a simple back reaction to catalyze and remove incorrect ribonucleotides, by reincorporation of PPi. This is known as:
A. pyrophosphorolytic editing
B. hydrolytic editing
C. RNA editing
D. exonuclease editing
2. RuvC is the catalyst for:
A. branch migration
B. resolution of Holliday junctions
C. assembly of strand exchange proteins
D. Holliday junction recognition

3. RecA protein is important in what recombination step:
A. paring homologous DNAs
B. strand invasion
C. introduction of DSBs
D. both A and B
E. both B and C

4. In E.coli the predominant σ factor is:
A. σ70
B. σ28
C. σ32
D. σ54

5. Which RNA splicing class carries out two transesterification reactions at branch site G?
A. Group I introns
B. Group II introns
C. Nuclear pre-mRNA
D. all answers are correct

6. Production of multiple mRNAs from a single transcript is called
A. alternative splicing

B. trans splicing

C. cis splicing

D. minor splicing

7. rut sites are ill-defined RNA elements involved in _____________ transcription termination.
A. Rho-dependent

B. Rho-independent

C. rut dependent

D. dyad dependent

8. Female development in the fly depends on the ___________ protein to regulate the expression of the _____________ protein and synthesis of a truncated Dsx protein which represses male genes.
A. Sxl, Tra

B. Sxl, Tra-2

C. Tra, Tra-2

D. Tra,Sxl

9. In order for an RNA molecule to be transported into the cytosol, __________ must be bound.
A. all answers are correct

B. proteins involved in capping

C. protein mediating polyadenylation

D. SR proteins
10. RNA polymerase __________ need a primer and transcription is ___________ accurate than DNA replication.
A. does not, less
B. does not, more
C. does, less
D. does, more

11. A series of λ mutations that disrupt the ability of the phage to complete its life cycle have been isolated.  With a mutation in the Xis gene, the following would occur:
A. No integration
B. No DNA alignment
C. No integration or excision.
D. No excision.

12. Phosphorylation of the CTD leads to an exchange of initiation factors for those factors required for
A. polyadenylation and cleavage factors
B. capping enzymes
C. components of splicing
D. all answers are correct

13. Chi sites can be defined as:
A. A specific eight-base-pair sequence that inhibits the frequency of homologous recombination by the RecBCD pathway in bacteria.
B. A specific eight-base-pair sequence that stimulates the frequency of homologous recombination by the RecBCD pathway in eukaryotes.
C. A specific eight-base-pair sequence that stimulates the frequency of homologous recombination by the RecBCD pathway in bacteria.
D. A specific eight-base-pair sequence that stimulates the frequency of homologous recombination by the RuvBCD pathway in bacteria.

14. A series of λ mutations that disrupt the ability of the phage to complete its life cycle have been isolated. If there is mutation in the crossover region within the attP site, the following will happen:
A. No excision
B. No insertion
C. No insertion or duplication
D. No insertion or excision

15. The spliceosome carries out ______________ reactions to remove introns and splice exons back together.
A. transesterification
B. hydrolysis
C. isomerization
D. exothermic

16. Transposons need to __________________ in order to limit their negative impact on the genome of the host cell.
A. control their nucleotide length
B. avoid transposing into their own genome
C. regulate their copy number
D. control their target-site choice
E. Both C and D are plausible

17. Isomerization of RNA polymerase, bearing σ70, _____________ require energy derived from ATP hydrolysis , and is ________________.
A. does not, irreversible
B. does not, reversible
C. does, irreversible
D. does, reversible

18. Which eukaryotic biological process(es) rely on homologous recombination:
A. repair of double strand breaks
B. rescuing stalled replication forks
C. recombination with foreign DNA
D. meiotic recombination
E. all of the above

19. The most highly conserved sequence at a splice site is
A. 5′-GU AG-3’
B. 5′-GA GT-3′
C. 5′-GU AT-3′
D. 5′-AC AG-3′

20. During initial transcription, _____________ allows a flexible element within the polymerase to move downstream, synthesizing short transcripts before aborting and retracting to the body of the enzyme, still at the promoter.
A. inchworming

B. transient excursion

C. scrunching

D. ratcheting