RNA polymerase ______________. binds tightly to a region of DNA thousands of bas

Question

RNA polymerase ______________.

binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed.

separates DNA strands throughout a long region of DNA (up to thousands of base pairs), then copies one of them.

can synthesize RNA chains de novo (without a primer).

has a subunit called (lambda), which acts as a proofreading ribonuclease.

synthesizes RNA chains in the 3' 5' direction.

3.5 points   

QUESTION 17

RNA polymerase forms phosphodiester bonds with the concomitant release of pyrophosphate (PPi).The subsequent conversion of pyrophosphate to _________ by pyrophosphatase drives the reaction in the direction of RNA synthesis.

deoxyribonucleotide (dNTP)

diphosphate (DePP)

ribonucleotide (rNTP)

water (H20)

inorganic phosphate (orthophosphate, Pi)

3.5 points   

QUESTION 18

A partial sequence of an mRNA is: 5'- AUG CAU AGC AAA GUC ACA AUC -3' The sequence of the corresponding DNA coding strand is 5'- Blank 1 Blank 2 Blank 3 Blank 4 Blank 5 Blank 6 Blank 7 -3' (Fill in the blanks in groups of 3-nucleotides.)

3.5 points   

QUESTION 19

A partial sequence of an mRNA is: 5'- AUG CAU AGC AAA GUC ACA AUC -3'. The sequence of the DNA non-coding strand corresponding to the mRNA sequence is 5'- Blank 1 Blank 2 Blank 3 Blank 4 Blank 5 Blank 6 Blank 7 -3' (Fill in the blanks in groups of 3-nucleotides.)

3.5 points   

QUESTION 20

Sigma factors ______________.

constitute part of the bacterial RNA polymerase holoenzyme.

facilitate promoter identification by RNA polymerases, are highly conserved proteins (that is, share considerable sequence homology in prokaryotes and eukaryotes) and are therefore known as general transcription factors

are general transcription factors that facilitate transcription of “general” constitutive genes by bacterial RNA polymerases, whereas in regulated genes similar functions are carried out by specialized factors such as the CAP (CRP) in the case of the lac operon.

constitute part of the bacterial RNA polymerase core enzyme.

3.5 points   

QUESTION 21

The promoters of E. coli can be grouped according to sequence similarity, but the sequences are rarely identical.

True

False

3.5 points   

QUESTION 22

The subunit makeup of the E. coli RNA polymerase core is

22&;

2'

2'

22&;

3.5 points   

QUESTION 23

The 10 and 35 sequences in bacterial promoters are separated by about two turns of the DNA double helix. How would transcription be affected if a deletion were introduced in the promoter region that moved the 35 sequence to the 29 position?

The deletion would move the 35 sequence closer to the 10 sequence by half a helical turn of the DNA. Since the actual sequences of the two promoter elements are not altered, we don't expect their being somewhat more proximal to one each other to be a major factor in the performance of the promoter.

The deletion would move the 35 sequence closer to the 10 sequence by full a helical turn of the DNA, putting the two elements on the same original face of the DNA duplex, only a bit closer. This would not dramatically affect the binding of sigma factor to the promoter nor make much of difference in the transcription efficiency.

The deletion would move the 35 sequence closer to the 10 sequence by full a helical turn of the DNA, putting the two elements on the same original face of the DNA duplex, but closer. This would dramatically increase the binding of sigma factor to the promoter by allowing it to more efficiently interact with the promoter, thereby increasing transcription efficiency.

The deletion would move the 35 sequence closer to the 10 sequence by half a helical turn of the DNA, putting the two elements on opposite faces of the DNA duplex. This would dramatically reduce binding of sigma factor to the promoter, thereby decreasing transcription efficiency.

binds tightly to a region of DNA thousands of base pairs away from the DNA to be transcribed.

separates DNA strands throughout a long region of DNA (up to thousands of base pairs), then copies one of them.

can synthesize RNA chains de novo (without a primer).

has a subunit called (lambda), which acts as a proofreading ribonuclease.

synthesizes RNA chains in the 3' 5' direction.

Explanation / Answer

Question 16

RNA polymerase can synthesize RNA chains de novo (without a primer)

Question 17

Answer: (E) inorganic phosphate (orthophosphate, Pi)

RNA polymerase forms phosphodiester bonds with the concomitant release of pyrophosphate (PPi).The subsequent conversion of pyrophosphate to inorganic phosphate (orthophosphate, Pi)  by pyrophosphatase drives the reaction in the direction of RNA synthesis.

Question 18

The sequence of corresponding coding DNA strand is 5'- ATG CAT AGC AAA GTC ACA ATC -3'

Question 19

The sequence of corresponding non-coding DNA strand is 5' - GAT TGT GAC TTT GCT ATG CAT - 3'

Question 20

Sigma factors constitute part of the bacterial RNA polymerase holoenzyme.

Question 21

True

Question 22.

The subunit makeup of the E. coli RNA polymerase core is 2'

Question 23

The deletion would move the 35 sequence closer to the 10 sequence by half a helical turn of the DNA, putting the two elements on opposite faces of the DNA duplex. This would dramatically reduce binding of sigma factor to the promoter, thereby decreasing transcription efficiency.

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