Ch. 17a Prokaryotic & Eukaryotic Transcription (Exam 2)

Question 1

What is transcription?

Answer 1

RNA synthesis

Question 2

In prokaryotes, where part of the gene does RNA polymerase bind to?

Answer 2

Promoter

Question 3

What is a promoter?

Answer 3

Start of the gene

Question 4

What is a terminator sequence?

Answer 4

Portion of gene where transcription ends

Question 5

What is a transcription unit?

Answer 5

Nucleotide sequence that codes for a single RNA molecule

Question 6

What 3 things does the transcription unit consist of?

Answer 6

1) Promoter
2) RNA-coding sequence
3) Terminator

Question 7

Define upstream.

Answer 7

Sequences prior to start point of transcription

Question 8

Define downstream.

Answer 8

Sequences that come after the start point of transcription

Question 9

Transcription sequences are usually written…

Answer 9

Left (upstream) to right (downstream)

Question 10

Transcription is 5’-3’ on a template that is…

Answer 10

3’-5’

Question 11

Is the RNA strand identical to the template or coding strand?

Answer 11

Coding strand

Question 12

Since the RNA strand is identical to the coding strand, then it is complementary to the…

Answer 12

Template strand

Question 13

Since RNA is complementary to the template strand, it can be referred to as the { } strand.

Answer 13

Nontemplate strand

Question 14

What happens during initiation?

Answer 14

Promoter is recognized and RNA polymerase binds to the duplex DNA, where it is unwound

Question 15

What happens during elongation?

Answer 15

Transcription bubble extends from 5’ to 3’ as polymerase synthesizes RNA

Question 16

What happens during termination?

Answer 16

Transcription stops once the RNA polymerase and RNA are released from the DNA duplex

Question 17

What is the purpose of the transcription bubble?

Answer 17

It allows the DNA to separate so that RNA can be crafted from the template strand

Question 18

Why is RNA polymerase a holoenzyme?

Answer 18

It is a combination of enzymes that work together for a common function

Question 19

What are the 2 key components of RNA polymerase?

Answer 19

1) Core enzyme
2) Sigma factor

Question 20

Which 2 subunits make up most of the core enzyme’s mass?

Answer 20

Beta & beta-prime

Question 21

This dimer is formed by two { } to provide the backbone for the core enzyme.

Answer 21

Alpha

Question 22

What is the purpose of the omega subunit?

Answer 22

Promoter recognition and transcription initiation

Question 23

What is the purpose of the sigma factor?

Answer 23

To ensure bacterial RNA polymerase initiates transcription at specific spots instead of binding at non-specific sequences

Question 24

The -35 element/region houses the…

Answer 24

TTGACA hexamer

Question 25

The -10 element/region houses the…

Answer 25

TATA box

Question 26

What is the difference between a closed and open binary complex?

Answer 26

Closed complex has no transcription bubble

Question 27

What happens at the ternary complex?

Answer 27

Sigma factor is released so that core enzyme can go forward transcribing

Question 28

What is happening to the DNA duplex during RNA elongation?

Answer 28

The duplex is being simultaneously wound and unwound

Question 29

Why is it important for RNA polymerase to stabilize the link between RNA and DNA?

Answer 29

Base pairing between both molecules is not too stable, and premature release from base pairing could mean premature interruption of elongation

Question 30

What is the rho factor?

Answer 30

Termination protein that binds to newly formed RNA and interacts with the polymerase to that it can be released

Question 31

What type of bonds between the DNA and RNA needs to be broken for termination to be achieved?

Answer 31

Hydrogen bonds

Question 32

Intrinsic terminators do not require a rho factor but no require this structure…

Answer 32

Hairpin loop

Question 33

What is the purpose of the hairpin loop?

Answer 33

It makes the RNA polymerase slow down and eventually dissociate from the DNA duplex

Question 34

What nucleotide duplex is the hairpin loop very rich in?

Answer 34

GC

Question 35

How does the rho factor work?

Answer 35

It uses helicase activity to unzip the DNA/RNA hybrid and release the RNA transcript

Question 36

The rho factor requires helicase & { } to operate.

Answer 36

ATP

Question 37

What is messenger RNA (mRNA)?

Answer 37

The transcript to be used in translation