L18

Question 1

What is an advantage to DNA containing thymine (T) instead of uracil (U)?

Answer 1

because the cell can then recognize the U that is produced by spontaneous deamination of C, and remove it

Question 2

Which of the following is NOT true about RNA?

RNA is less stable than DNA

RNA probably existed before DNA

RNA allows additional levels of regulation

RNA can have enzymatic activity

ALL of the above are true

Answer 2

ALL of the above are true

Question 3

replication direction

Answer 3

5’ –> 3’

Question 3

transcription direction

Answer 3

5’ –> 3’

Question 4

substrate for replication

Answer 4

dNTPs using DNA polymerase

Question 5

replication speed

Answer 5

1000nt/s

Question 6

replication error rate

Answer 6

10^-10

Question 7

sliding clamp: replication or transcription?

Answer 7

replication

Question 8

primer: replication or transcription

Answer 8

replication: RNA primer

Question 9

transcription substrate

Answer 9

NTPs using RNA polymerase

Question 10

transcription speed

Answer 10

50nt/s

Question 11

transcription error rate

Answer 11

10^-4 to 10^-5
less accurate than replication

Question 12

what undergoes spontaneous deamination?

Answer 12

Cytosine deamination –> uracil, which could bind to adenine

Adenine deamination –> hypoxanthine, which could bind to cytosine

Question 13

promoter

Answer 13

cis-acting DNA sequence, tell transcription machinery where to initiate

Question 14

coding

Answer 14

Sense

Question 15

Which enzyme catalyzes transcription of the majority of protein-coding genes in the cell?

A. DNA Polymerase I

B. DNA Polymerase II

C. RNA Polymerase I

D. RNA Polymerase II

E. RNA Polymerase III

Answer 15

D. RNA Polymerase II

Question 16

RNAP I

Answer 16

synthesizes most rRNA, resides in nucleolus

Question 17

RNAP II

Answer 17

synthesizes most mRNA, resides in nucleoplasm

Question 18

RNAP III

Answer 18

synthesizes 5S rRNA, tRNA, and many other RNA types; resides in nucleoplasm

Question 19

Which of the following most accurately describes the relative abundance (by total mass) of RNA species inside cells?
Response recorded

A. mRNA < rRNA < tRNA

B. mRNA < tRNA < rRNA

C. rRNA < tRNA < mRNA

D. tRNA < mRNA < rRNA

E. tRNA < rRNA < mRNA

Answer 19

B

Question 20

pre-initiation complex (PIC)

Answer 20

RNAP II and general transcription factors (GTFs)

Question 21

enhancer sequences

Answer 21

• regulate activity of core promoters
• specific ones bind different “activator” transcription factors
• each gene has a different array of enhancer sequences

Question 22

TATA-binding protein (TBP)

Answer 22

• key subunit of TFIID (step 1)
• introduces a 45 degree bend into the double helix, locally untwisting the DNA
• universal GTF required for RNAP I, II, and III initiation

Question 23

Which of the following best describes the function of enhancers in gene regulation?

A. They are DNA sequences that directly bind RNA polymerase and regulate transcriptional initiation.

B. They are DNA sequences that directly bind TFIID, and regulate transcriptional initiation.

C. They are DNA sequences that directly bind transcription factors and regulate transcriptional initiation.

D. They are DNA sequences that directly bind transcription factors and regulate transcriptional elongation.

E. They are mRNA sequences that directly bind initiation factors and regulate translational initiation.

Answer 23

C. They are DNA sequences that directly bind transcription factors and regulate transcriptional initiation.

Question 24

sigma factor proteins

Answer 24

direct RNAP to the promotor for transcription in bacteria

Question 25

mediator

Answer 25

huge protein complex of >20 subunits that activators use to regulate transcription

Question 27

Which of the following is NOT a common chromatin mark? Response recorded Methylation of DNA Methylation of histones Acetylation of DNA Acetylation of histones ALL of the above are common chromatin marks

Answer 27

Acetylation of DNA

Question 28

Given that the human genome has 42% G and C in total, what is the expected frequency of CpG dinucleotides? You can respond once A. 1% B. 4% C. 8% D. 16% E. 20% F. There’s not enough info to answer this.

Answer 28

B. 4%

Question 29

Which statement about mRNA splicing is FALSE? Response recorded A. The process is carried out by the spliceosome. B. Splicing can generate different mRNAs from a single gene. C. The lariat forms when a ribose 2’-OH within the intron attacks the phosphoester bond at the 5' splice site, breaking the old phosphoester bond and making a new one. D. The lariat RNA becomes part of the mature mRNA. E. The 2 nucleotides at the 5' and 3' ends of the introns are nearly invariant.

Answer 29

D. The lariat RNA becomes part of the mature mRNA.

Question 30

Which of the following best characterizes the termination of transcription in eukaryotes? A. The sequence signals for termination of transcription are contained within the transcript itself. B. The

Answer 30

The sequence signals for termination of transcription are contained within the transcript itself.

Question 31

Mutagen X causes G to A mutations on the sense strand, while mutagen Y causes A to T mutations on the sense strand. Which mutagen would you expect to have the most deleterious effect on the protein? You can respond once X Y They would have the same effect Not enough info to answer this None of the above

Answer 31

Tab

Question 33

Template

Answer 33

Antisense