Test 2- Transcription And Translation

Question 1

Template strand

Answer 1

Read by RNA polymerase

Question 2

Sense strand

Answer 2

Unread strand of DNA; look like RNA produced.

Question 3

-35 box

Answer 3

TTGACA

Question 4

Pribnow box

Answer 4

TATAAT

Question 5

Prokaryotic holoenzyme

Answer 5

Core polymerase and sigma factor

Question 6

Sigma factors

Answer 6

70- most promoters
32- heat shock
54- nitrogen starvation
28- motility and chemotaxis

Question 7

Prokaryotic transcription initiation and elongation

Answer 7

RNA polymerase binds
~10nt added
Sigma factor released 
Elongation
3' and 5' exonuclease and endonuclease activity

Question 8

Exonuclease

Answer 8

1 bp at a time

Question 9

Endonuclease

Answer 9

Multiple bps at a time

Question 10

Prokaryotic transcription termination

Answer 10

Terminator sequences signal end

-rho dependent vs. rho independent

Question 11

Rho independent

Answer 11

Inverted repeat ~20 bp upstream of termination followed by 4-8 AT bps
Forms hairpin loop
RNA pol terminates bc of weak AU bps

Question 12

Rho dependent

Answer 12

Rho protein binds to terminator sequence and uses ATPase to dissociate RNA pol

Question 13

Prokaryotic v. Eukaryotic transcription

Answer 13

mRNA processing

RNA polymerase

Question 14

Euk. RNA pol

Answer 14

Pol I- 28s, 18s, 5.8s rRNA
Pol II- mRNA, snRNA
Pol III- tRNA, 5s RNA, snRNA

Question 15

Euk. Promoter

Answer 15

Core promoter: TATAAAA ~-30
Proximal promoter: CAAT ~-75
+enhancers binding to gene reg. proteins

Question 16

Euk. Transcription initiation

Answer 16

TFIID (TBP + TAFs) binds to TATA box
TFIIA and TFIIB bind
RNA pol II w/ TFIIF binds
TFIIE and TFIIH bind to form complete txn initiation complex

Question 17

5’ cap

Answer 17

7-methyl guanosine
Cotranscriptional 
After synthesis of ~20nt
Protects from exonucleases
Required for exiting nucleus
Binds 5'-5'
Methylates 1-3 sugars

Question 18

Polyadenylation

Answer 18

50-200 As 
Required for nuclear export 
Cotranscriptional
CPSF, CstF, and CFI and CFII bind and cleave at polyA site
PAP and PABII add As

Question 19

Splicing

Answer 19

5'GU and 3' AG recognized
snRNPs (snRNA + protein) form spliceosome with mRNA
SnRNA- U12456
U1- binds 5' junction
U2- binds branch point
U4u6u5 bind and form loop
U4 dissociates
5' junction cleaved intron attaches to branch point A
3' cleavage 
Exons ligate

Question 20

Prok. rRNA txn

Answer 20

Multiple RNA encoded in one unit of DNA which is separated by spacers

Question 21

RNA pol I

Answer 21

Non transcribed, external, and internal transcribed spacers separate 18, 5.8, and 28s rRNA

Question 22

RNA pol III

Answer 22

5s rRNA, tRNA, snRNA

Promoters for rRNA and tRNA within coding region.

Question 23

RNA editing

Answer 23

Editing of mitochondrial mRNA postranscriptionally

Question 24

Primary structure

Answer 24

Amino acid sequence

Question 25

Secondary structure

Answer 25

a-helix and b-sheets formed by hydrogen bonding

Question 26

Tertiary structure

Answer 26

Further polypeptide folding

Question 27

Quaternary structure

Answer 27

Multiple polypeptide units bound

Question 28

Triplet code discovery

Answer 28

Experiments by crick and brenner with t4 | Base deletions, additions caused frame shifts

Question 29

Characteristics of genetic code

Answer 29

``` Triplet Continuous Non overlapping Nearly universal Degenerate Start and stop signals Wobble ```

Question 30

Start codon

Answer 30

Aug

Question 31

Stop codons

Answer 31

UAG UAA UGA

Question 32

Wobble codes

Answer 32

G an U can pair | I can pair with AUC

Question 33

tRNA

Answer 33

From spacer regions of rRNA Anticodon in loop II Amino acid attached to CCA3'

Question 34

Aminoacylation

Answer 34

aa-tRNA synthetase binds amino acid and ATP ATP is hydrolyzed uncharged tRNA binds to enzyme aa transferred to tRNA

Question 35

Prokaryotic ribosome

Answer 35

``` 70s ribosome 50 S large subunit 23S and 5s rRNA 30S small subunit 16 S rRNA ```

Question 36

Eukaryotic ribosome

Answer 36

``` 80s ribosome 60s large subunit 28s, 5.8s, 5s rRNA 40s small subunit 18s rRNA ```

Question 37

Prokaryotic translation initiation

Answer 37

Shine Dalgarno sequence recognized by small subunit with IF 1&3 fMet binds with help of IF2 Large subunit is recruited GTP hydrolyzed; IFs leave

Question 38

Eukaryotic translation initiation

Answer 38

eIF-4F binds to mRNA 5'cap 40s, eIFs, GTP, met-tRNA bind Complex scans mRNA for AUG in Kozak consensus sequence 60s binds; eIFs leave

Question 39

Translation elongation

Answer 39

fMet-tRNA is in p site Next aa-tRNA binds at A site with EF-tu and GTP Peptidyl transferase catalyzes joining of aas Ribosome translocates using EF-G and GTP Uncharged tRNA is released through E site

Question 40

Polysome

Answer 40

Multiple ribosomes translating one mRNA

Question 41

Translation termination

Answer 41

``` RF1 binds to stop codon Polypeptide chain released RF3-GDP binds releasing RF1 GTP is hydrolyzed to release RF3 RRF binds to A site EF-G-GTP binds and hydrolyzes GTP to translocate ribosome EF-G releases RRF releases tRNA Ribosome dissociates ```

Question 42

Release factors

Answer 42

``` E. coli RF1 for UAA and UAG RF2 for UAA and UGA RF3 stimulates termination Eukaryotes eRF1 recognizes all codons eRF3 stimulates termination ```

Question 43

Secreted proteins

Answer 43

Signal peptide is bound by SRP stopping translation SRP binds to docking protein Signal peptide binds to signal peptidase translation resumes and peptide goes into ER lumen Signal peptide cleaved Translation completes polypeptide released into ER

Question 44

SRP

Answer 44

Signal recognition particle Polypeptide+RNA RNA Blocks A site Polypeptide recognizes signal peptide and docking protein