5 Transcription

Question 1

what direction is RNA synthed in?

Answer 1

5-3

Question 2

what links nucleotides in RNA?

Answer 2

5-3 phosphodiester bonds

Question 3

What pol synth RNA?

Answer 3

DNA dep RNA pol needs 3’ OH and read 3-5 but synths 5-3

Question 4

what are the components of prok RNA pol?

Answer 4

alpha/beta 4 unit core and single sigma factor

Question 5

what is the function of the sigma factor

Answer 5

scans for pribnow boxes to initiate transcription

Question 6

what does RNA pol I make?

Answer 6

rRNA w/o 5S

Question 7

what does RNA pol II make?

Answer 7

mRNA

Question 8

<p>

| what does RNA pol III make?</p>

Answer 8

<p>

| tRNA, sRNA like 5S</p>

Question 9

how does the DNA and RNA sequences relate after transcription?

Answer 9

RNA is complementary to template strand and identical with T->U swap as the coding DNA strand

Question 10

what are the RNA comparisons in terms of maturity before translation between euks and proks?

Answer 10

prok RNA are made from polycis genes so they have all components that are needed for a given function, they are dumped into the cyto, they do not have post tran mods.

Euk transcription is in nuc, has introns removed and exons spliced, has methyl cap and poly a tail added before exiting nuc

Question 11

how does poly know which sequences it needs to transcribe?

Answer 11

it looks for non coding promoter regions

Question 12

how does DNA promotor elements compare between euk and prok?

Answer 12

prok has TTGACA at -35 and pribnow at -10
euks have random upstream enhancers as well as promoter elements along with CAAT/GC regions at -40-(-100) and TATA at -25

Question 13

what is the RNA tran complex for euks consist of?

Answer 13

TFIIA and cofactors bind to TFIID(aka TBP) which looks for TATA box, TBP also is bound to TFIIBFEH which holds RNA pol

Question 14

How does coactivators work?

Answer 14

coactivators(tran) search for enhancer sequences(cis) away from coding sequence which increase rate of transcription while repressors(trans) silencers(cis) will decrease transcription rate

Question 15

what class of receptors can bind directly to DNA

Answer 15

steroid receptors can bind directly to and regulate DNA (ie. activation)

Question 16

what is the purpose of the 5’ methyl cap and 3’ polyAtail?

Answer 16

cap protects against RNAse, polyAtail protects and signals export

Question 17

how is the polyAtail added?

Answer 17

polyApolymerase will recognize AAUAAA after RNAse cleaves after it and will add random amounts of A

Question 18

how is splicing performed?

Answer 18

snRNPs will recognize AGGU and AGG(U) of an exon-intron barrier and will bind U1 and U5 while U2 will bind a random A, complex of U12456 will forma lariat structure and excise the intron and splice the exons in one go

Question 19

ribosomes are creation occurs where mostly?

Answer 19

45S precursor will be formed in the nucleolus which then splits off into 20S for the 40S subunit and the 5S/32S for the 60S subunit which will bind again in cyto

Question 20

What contributes to cloverleaf pattern of tRNA and what associates with amino acids

Answer 20

base pairing gives structure, post tran modded 3’ CCA carries AA

Question 21

Why is actinomycin D too dangerous for clinical use?

Answer 21

sterically hinders replication and transcription

Question 22

what drugs can treat tuberculosis and meningitis and how?

Answer 22

rifampin inhibits initiation by binding to beta unit of RNA poly and inhibiting initial formation of phosphodiester bond

Question 23

what bacterial transcription mechanism prevents elongation?

Answer 23

streptolydigin

Question 24

how does alpha amatin work

Answer 24

toxin from deathcap inhibits euk RNA pol II and thus blocks mRNA synth -> can lead to death or liver failure