Transcription and disorders

Question 1

RNAP

Answer 1

uses DNA as a template, synthesizing in the 5’-3’ direction while reading in the 3’-5’ direction. Does not require a primer, and cannot proofread, so error rate is high.

Question 2

major points of prok translation

Answer 2

1. 1 type of RNAP for all RNA
2. uses sigma factor as TF
3. promoter escapes via DNA scrunching
4. Termination is Rho-dependent or Rho-independent

Question 3

prok promoter regions

Answer 3

Pribnow box 10 bp, 35 bp.

Question 4

euk promoter regions

Answer 4

TATA box, many others - each specific for its assembly role.

Question 5

euk initiation

Answer 5

**each step of assembly has its own TF

**helicase unwinds DNA

**CTD (carboxy terminal domain) is phosphorylated, thus ACTIVE, allows promoter escape

Question 6

euk elongation

Answer 6

uses elongation factors to bind RNAP

Question 7

euk termination

Answer 7

EFs dissociate, CTD dephosphorylated thus inactive, termination signal read and poly A tail added

Question 8

prok elongation

Answer 8

• promoter escapes via DNA scrunching

- sigma factor recycled

Question 9

prok termination

Answer 9

rho dependent or rho independent

Question 10

inhibitor of prok RNAP

Answer 10

Rifampin, used to treat leprosy and TB, blocks the beta subunit of RNAP thus blocking active site

Question 11

inhibitor of euk RNAP

Answer 11

alpha-amanitin, produced by mushroom, toxin binds to largest subunit of RNAP

Question 12

rho-dependent termination

Answer 12

rho helicase uses ATP to snip off the new mRNA

Question 13

rho-independent termination

Answer 13

palindromic G/C rich hairpin forms which stops RNAP and U rich tail is pulled out of RNAP

Question 14

post-translational mods of pre-RNA in euks only

Answer 14

1. 7 methylguanosine cap at 5’ end
2. splicing thru spliceosome
3. poly A tail at 3’ end (gets shortened thru lifespan)
4. export from nucleus

Question 15

viral cap snatching

Answer 15

virus replicates host cap on mRNA for more efficient translation by ribosomes, as well as protection from proteases and foreign detection

Question 16

spliceosome

Answer 16

consists of snRNPs made up of snRNAs that are rich in uridine (U1,2,4,5,6).
The snRNPs excise the introns from mRNA and ligase seals the exons together with exon junction complex.

Question 17

retinitis pigmentosa

Answer 17

degenerative disease that causes progressive loss of night and peripheral vision due to rod cell death; rod cells die because of build up of unprocessed/misprocessed Rhodopsin pigment which is controlled by 4 snRNP proteins which are implicated in the disease

Question 18

systemic lupus erythematous

Answer 18

patient makes antibodies for snRNPs which are ubiquitously expressed, thus has widespread inflammation, butterfly rash, muscle aches, arthritis.
ANA screen tests for antinuclear anbodies.

Question 19

polyadenylation disorders

Answer 19

alternative polyadenylation has uses in neurons and cell diff but causes the length of the 3’ UTR to change, thus possibly changing the binding sites of microRNA

assc with many diseases including type 1+2 DM, fragile X associated OI, cancers