Transcription

Question 1

Groups of genes expressed together in prokaryotes

Answer 1

Operons

Question 2

How many RNA polymerases do prokaryotes have?

Answer 2

1

Question 3

Name and type RNA pol in eukaryotes

Answer 3

Pol I: rRNA
Pol II: mRNA
Pol III: tRNA

Question 4

How are the RNA pol in eukaryotes specific to the type of RNA they produce?

Answer 4

Recognize different promoter sequences

Question 5

This protein binds to bacterial promoters to direct RNA Pol to the correct region

Answer 5

Sigma factor

Question 6

T/F Transcription can occur on opposite DNA strands simultaneously

Answer 6

T

Question 7

Two physical factors that terminate prokaryotic RNA Pol

Answer 7

1. Hairpin loop

2. Rho factor binding

Question 8

Term for DNA sequence that encodes one polypeptide

Answer 8

Cistron

Question 9

How many introns does the typical prokaryotic cistron contain?

Answer 9

0

Question 10

Describe bacterial RNA transcription

Answer 10

1. Sigma factor binds RNA promoter region
2. RNA Pol binds DNA strand and begins transcription
3. Sigma factor falls off
4. RNA Pol transcription continues
5. Transcription is terminated at hairpin or Rho factor

Question 11

Three basic steps of eukaryotic RNA processing

Answer 11

1. 5’ cap
2. 3’ poly-A tail
3. Intron removal

Question 12

T/F Intron removal occurs in the cytosol

Answer 12

F (it occurs in the nucleus)

Question 13

These transcription factors are required for all eukaryotic RNA Pol transcriptions

Answer 13

General transcription factors

Question 14

Steps of eukaryotic RNA Pol II initiation

Answer 14

1. TFI proteins (general transcription factors) bind promotor region
2. RNA Pol and other general transcription factors bind
3. Helicase + phosphorylation activation
4. General transcription factors removed
5. Off it goes

Question 15

T/F Enhancers are DNA sequences that bind activator proteins that are always close to the site of transcription

Answer 15

F

Question 16

These proteins help RNA Pol II move along DNA sequences

Answer 16

Elongation factors

Question 17

T/F 5’ capping begins DURING transcription

Answer 17

T

Question 18

Structure that helps ensure accurate splicing

Answer 18

Spliceosome

Question 19

Two separate two-nucleotide sequences that are invariant in coding the beginning and end of introns

Answer 19

GU (begin)

AG (end)

Question 20

Describe the steps in mRNA splicing

Answer 20

1. Nucleophilic intronic adenine attacks 5’ end of intron
2. The now freed –OH on exon attacks other exon
3. Lariat loop is released and exons are joined

Question 21

How can our genome have ~30,000 start codons but we produce far more proteins?

Answer 21

Alternative splicing

Question 22

MicroRNAs are transcribed using which RNA Pol

Answer 22

II