11 Gene Expression: From Transcription to Translation

Question 1

2 general Functions of RNA polymerase

Answer 1

i. Digest incorrect nucleotides (proofreading)

ii. Polymerization (mRNA synthesis)

Question 2

Function of rRNA

Answer 2

recognize other molecules, provide structural support; catalyze chemical reaction

Question 3

Function of tRNA

Answer 3

tRNA translate information of mRNA to amino acids

Question 4

RNA polymerase requires the help of ______ to recognize promoter

Answer 4

transcription factors, or general transcription factors (GTF)

Question 5

Does RNA polymerase move from 3’ to 5’ or 5’ to 3’ along DNA? What is the direction of RNA transcription?

Answer 5

3’ to 5’; 5’ to 3’

Question 6

Studying properties of RNA polymerase is hard True or False

Answer 6

True (from lecture 17)

Question 7

RNA polymermase is said to be processive when….?

Answer 7

remain attached to DNA over long stretch

Question 8

How many types of RNA polymerase are there in bacteria

Answer 8

1

Question 9

How many subunits are there in bacteria RNA polymerase

Answer 9

5 subunits form core enzyme

Question 10

What is sigma factor? in eukaryote or prokaryote?

Answer 10

aids core enzyme to bind to initiation sites for transcription; is loss as RNA chain is elongated

Question 11

State the 3 RNA Eukaryotic Polymerase and their function

Answer 11

RNA polymerase 2 transcribes mRNA
RNA polymerase 1 transcribes rRNA
RNA polymerase 3 transcribes tRNA

Question 12

What is GTF? if combined with RNA polymerase 2, what does it form?

Answer 12

GTF = General transcription factors; it forms PIC (preinitiation complex) with RNA polymerase 2

Question 13

where is TATA box located?

Answer 13

promoter region

Question 14

Why Thymine is used in DNA but Uracil is used in RNA

Answer 14

1. Thymine is more energy expensive

2. Cytosine degrade to uracil; makes it hard to detect mutation of U is used in DNA

Question 15

A the very beginning of mRNA transcription, what binds to TATA box

Answer 15

TBP - TATA binding Protein

Question 16

What is TBP a subunit of?

Answer 16

TFIID

Question 17

As long as __(GTF)___ is attached to DNA, additional RNA polymerase can attach to DNA and transcribe.
(Name the GTF) **IMPORTANT

Answer 17

TFIID

Question 18

Function of TFIIA, TFIIB, TFIIE, TFIIF

Answer 18

TFIIA =Aids TBP,
TFIIB = Bridges the gap
E= DNA melting
F= recruitment 
(Lec19)

Question 19

2 ways TFIIH aid transcription

Answer 19

1. Act as Kinase;Catalyse CTD phosphorylation

2. Acts as Helicase; unwinds DNA

Question 20

Whats CTD

Answer 20

carboxyl terminal domain = 52 repeating 7-amino acid sequence attached to RNA polymerase

Question 21

Serine in CTD can/cannot be phosphorylated ?

Answer 21

can

Question 22

when transcribing, RNA polymerase is phosphorylated at where?

Answer 22

CTD

Question 23

name 2 functions of CTD phosphorylation

Answer 23

1. allows transcriptional machinery to separate from GTF

3. provide a docking site for RNA-processing proteins

Question 24

what does pre-RNA stand for?

Answer 24

primary transcript ; pre-RNA usually attach to protein

Question 25

Name 3 functions of 5’ methylguanosine cap

Answer 25

1. Prevent mRNA degrading due to exonuclease
2. assist mRNA transport out of nucleus
3. initiate mRNA translation

Question 26

Name 2 functions of 3’ Poly A tail

Answer 26

1. prevent premature mRNA (hnRNA) from degrading

2. Docking site for protein

Question 27

what is a split gene?

Answer 27

EUKARYOTIC genes containing intervening sequence

Question 28

Name 2 functions of introns

Answer 28

1. Alternate splcing (same DNA template; many protein isoforms)
2. exon shuffling
   NON-CODING DNA IS Functional!!!!

Question 29

How does RNA transcription begin in prokaryote?

Answer 29

1. RNA polymerase binds to either conserved regions (1.Pribnow box 2.-35 element) in upstream

Question 30

How does RNA transcription end in prokaryote

Answer 30

1. rho factors attachment

2. reach terminator sequence

Question 31

Steps of RNA transcription initiation

Answer 31

1. TFIID’s subunit TBP binds to TATA
2. other GTP such as TFIIA, TFIIB binds the TDIID—> forms PIC
3. RNA polymerase attach to the PIC
4. TFIIH catalyzes phosphorylation
   5, transcription is started