Lecture 3a

Question 1

Transcription

Answer 1

Copying of a segment of DNA into RNA sequence by the enzyme RNA polymerase

Question 2

RNA Polymerase

Answer 2

Multi subunit protein complex that produces RNA from DNA through transcription

Question 3

Spliceosome

Answer 3

Complex of snRNA and protein subunits that removes introns from a transcribed premRNA (hnRNA)

Question 4

Translation

Answer 4

Process where a protein (polypeptide) product is produced from mRNA, which requires amino acids, tRNA and ribsomes

Question 5

tRNA

Answer 5

High stable RNA molecule(70-95 nucelotides long) which is the adapter molecule between the mRNA and peptide sequences

Question 6

Ribosomes

Answer 6

Ribonucleoprotein complex composed of rRNAs and ribosomal proteins that catalyses the synthesis of protein using information provided by the mRNA

Question 7

What direction does transcription of the DNA strand take place?

Answer 7

3’ to 5’

Question 8

Ribonucleotides are added to what end of the growing RNA transcript?

Answer 8

3’

Question 9

What are the main 2 differences between DNA and RNA polymerase?

Answer 9

RNA has no proofreading mechanisms and does not require a primer to begin its process

Question 10

How many RNA polymerases do Pros and Euks carry

Answer 10

Pro has 1

Euk has 3

Question 11

Pro RNA Pol has how many subunits and name them?

Answer 11

6 Subunits

alpha1, alpha2, beta, antibeta, omega, and sigma

Question 12

What is the sixth sigma subits for in the RNA pol in Pros

Answer 12

Only required for initiation of RNA synthesis and is detachable

Question 13

What is the holoenzyme

Answer 13

RNA polymerase containing the sigma factor

Question 14

What are each of the 3 RNA polymerases in Euks used for?

Answer 14

Pol 1 is rRNA
Pol 2 is mRNA so for proteins
Pol 3 is tRNA

Question 15

3 stages of transcription?

Answer 15

Initiation, Elongation, Termination

Question 16

Transcription initiation in euks requires the function of 5 groups of proteins called?

Answer 16

General Transcription Factors (GTFs)

Question 17

What forms the RNA Polymerase II preinitiation complex?

Answer 17

RNA Polymerase and GTFs

Question 18

What is the TFIID and what are the 2 subunits?

Answer 18

One of the GTFs needed for transcription initiation. TBP and TAF subunits

Question 19

What does the TBP and TAF subunit do?

Answer 19

TBP recognises the TATA box.

TAF recognises other DNA sequences near the transcription start point; regulates DNA binding by TBP

Question 20

Give a general outline of the initiation of transcription in Euks, so the general outline of the assembluy of preinitiation complex

Answer 20

TFIID binds to the TATA box >

RNA Pol2 and additional GTF’s then bind at the TATA box > Preinitiation complex formed

Question 21

Name the 4 additional GTFs

Answer 21

TFIIB, TFIIF, TFIIE, TFIIH

Question 22

What does TFIIH do?

Answer 22

Acts to open the strands (like helicase) to form an open complex.
Also phosphorylates the C terminal (CTD) of RNApol at Ser5

Question 23

What 4 other things does RNAPol2 need to initiate transcription?

Answer 23

Mediator, Chromatin modifying proteins (SAGA), Chromatin remodeling complexes (SWI/SNF), Transcriptional activator proteins

Question 24

What is the CTD of RNAPol2?

Answer 24

Repeated series of a 7 amino acid sequence with 2 Serines in each sequences

Question 25

Phosphorylation of what Serine allows for what to happen in the transcriptional elongation in Euks?

Answer 25

Ser5 allows binding of capping proteins

Question 26

Elongation is accompanied by what transition?

Answer 26

Transition of phosphorylation from Ser5 to Ser2

Question 27

Transcriptional elongation requires the recruitment of what and why?

Answer 27

Of elongation factors to regulate RNAP activity (transcription rate) and Chromatin modifications

Question 28

mRNA has function?

Answer 28

Messenger RNAs | Codes for proteins

Question 29

rRNA has function?

Answer 29

Ribosomal RNA | Form the basic structure of the ribosome and catalyse the protein synthesis

Question 30

tRNA has function?

Answer 30

Transfer RNAs | Central to protein synthesis as adaptors between mRNA and amino acids

Question 31

snRNAs has function?

Answer 31

small nuclear RNAs | Function in a variety of nuclear processes, including the splicing of pre-mRNA

Question 32

snoRNAs has what function?

Answer 32

Small nucelolar RNAs | Process and chemically modify rRNAs

Question 33

scaRNAs

Answer 33

Small cajal RNAs | Used to modify snoRNAs and snRNAs

Question 34

miRNAS

Answer 34

MicroRNAs | regulate gene expresson typically by blocking translation of selective mRNAs

Question 35

siRNAS

Answer 35

Small interfering RNAs turn off gene expression by directing degradation of selective mRNAs and the establishment of compact chromatin structures

Question 36

Other noncoding RNAs?

Answer 36

Function in many processes, including telomere synthesis, X chromsome inactivtion and trasnport of proteins into ER

Question 37

Out of TFIID, TFIIB and TFIIF | 1) which binds first then second?

Answer 37

1) TFIID and then TFIIB then TFIFI