Transcription in Eukaryotes

Question 1

RNAP I

Answer 1

transcribe genes that encode large rRNA

Question 2

RNAPII

Answer 2

transcribes genes that encode proteins + some sRNA

-> all mRNA/ pre mRNA

Question 3

RNAPIII

Answer 3

transcribes genes that encode sRNA + RNA, ssrRNA

Question 4

Mitochondrial RNA P

Answer 4

Monomeric, similar to T3/ T7 bacteriophage

Question 5

RNAP II carries out what percentage of all cellular RNA synthesis?

Answer 5

20-40%

Question 6

RNAP sub-unit sizes

Answer 6

2 large/ 7-12 small

Question 7

Basal transcription complex is formed by ___

Answer 7

5 factors

Question 8

GTF consists of

Answer 8

TF II ( B, D, E, F, H)

Question 9

Eukaryotic consensus sequence

Answer 9

TATA - A/T’s are easy to unwind at -19/27 bp recruit RNAPII

Question 10

What happens when consensus sequence recognised?

Answer 10

1. TBP from TFIID binds to TATA
2. TBP forms a saddle-shaped clamp surrounding DNA + TATA box
3. TFIIA + B recruited
4. TFIIF binds to RNAPII:
   - decrease affinity for non-p region
   - helps form open complex

Question 11

In elongation _____ remains bound as _____ + _____ associates with transcribing polymerase

Answer 11

TFIIF, elongation factor, TFIIS

Question 12

Transcription is dictated by ____ state

Answer 12

Chromatin

Question 13

In what ways are post-translational modification made on histones?

Answer 13

1. Lys residues for methylation /acetylation
2. Arg -> methyl, ser/ thr phosphorylated
   => signals for activation / repression

Question 14

Where are post-transcriptional mods made on chromatin?

Answer 14

Terminal arms of 4 histones

Question 15

How are nucleosomes positioned/ remodelled?

Answer 15

Large multiprotein
-> some have HAT/ HDAC
complexes that gain energy from ATP hydrolisation physically remodel gene’s nucleosome + allow proteins to have DNA access

Question 16

Transcription regulation occurs by

Answer 16

Initiation of regulatory gene transcription regulated by proteins that bind to DNA sequence e.g. repressor/ activator
-> often allosteric

Question 17

Inducer

Answer 17

Inactivating ligands

Question 18

Corepressor

Answer 18

Activating repressor ligand

Question 19

Processing of pre - rRNA

Answer 19

1. Primary transcript is cut to yield mature rRNA’s formed in ribosomes
2. Modification : methylation of specific ribosome 2’OH
   -> conversion of uridine to pseduouridine
   => RNAPI

Question 20

Processing of tRNA, ssRNA, snRNA VD

Answer 20

Can be downstream promoter
- CCA + 3’OH
2. trimmed back by endonuclease
pol I, ii< iiii all bind to TATA