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601 EXAM 2 > 3.9 transcription review > Flashcards

3.9 transcription review Flashcards

1
Q

how is RNA different than DNA?

A
  • has uracil instead of thymine
  • hairpin loop most common structure
  • very prone to modifications/processing
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2
Q

how is RNA polymerase different than DNA polymerase ?

A
  • no primer needed
  • much slower
  • can synthesize bases de-novo
  • has its own helicase activity
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3
Q

what are the 4 basic steps of transcription?

A
  1. initiation
  2. elongation
  3. termination
  4. post-transcriptional modification in eukaryotes
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4
Q

how many subunits are bacterial RNA polymerases made of?

A

6

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5
Q

what are the two forms of bacterial RNAP

A

core (a2bb’w)
Halo (core + sigma)

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6
Q

_______ bacterial RNAP can bind to any DNA and start transcribing. ____ binds to core, converts it to holoenzyme, and has specificity

A

Core
sigma

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7
Q

Core RNA is useless until what?

A

sigma binds

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8
Q

promoter regions usually have what two specific regions in them?

A

-10,-35

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9
Q

if you add nucleotides you might not be able to see the __________ and promoters may not be able to bind

A

-35 and -10 regions

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10
Q

every bacteria has how many sigma factors?

A

multiple

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11
Q

steps of transcription initiation in bacteria?

A
  • sigma binds to RNAP
    -RNAP binds to promoter region
    -formation of open complex
  • transcription starts
    -initiation ends after first inter-nucleotide bond forms
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12
Q

what are some factors that affect transcription initiation?

A
  • promoter strength (how likely will they be recognized)
  • dna supercoiling (can. hide or open promoter seq)
    -UP element
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13
Q

does RNAP transcribe at a constant rate?

A

no!! it pauses every ~100 nucleotides

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14
Q

what are two ways that RNAP are modulated?

A

-hairpin pause (hairpin is formed, factors must come relieve it before RNAP can continue)
-backtrack pause (the way is blocked, must backtrack for Gre/Pi to chew away before RNAP can start again)

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15
Q

what happens during transcription termination?

A
  • cessation of elongation
  • release of transcript from ternary complex
  • dissociation of RNAP from complex
    -zipping back of DNA double strands
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16
Q

what are the 2 mechanisms of transcription termination?

A

factor independent and factor dependent

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17
Q

_______ is a polycistronic RNA that encodes for multiple gene products

A

an operon

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18
Q

rRNA is transcribed as a ______ transcript

A

30s

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19
Q

you need a 1:1:1 ratio of 16:23:5s rRNA for what to happen?

A

nuclease processing

20
Q

every tRNA has what?

A
  • G at 5’ end
  • ends with CCA
21
Q

bacterial RNAP can bind to _________ on its own but needs ______ for specificity

A

promoters, sigma

22
Q

bacterial RNAP has very little post-translational modifications except what?

A

rRNA and tRNA

23
Q

what does eukaryotic RNAP I transcribe?

A

most rRNA genes

24
Q

what does eukaryotic RNAP II transcribe?

A

protein coding genes, miRNA genes, some genes for small RNAs

25
Q

what does eukaryotic RNAP III transcribe?

A

tRNA, 5s RNA

26
Q

which promoters are more well defined: eukaryotic or prokaryotic

A

prokaryotic

27
Q

_____ are areas of DNA that dont code for a protein

A

intron

28
Q

_________ help euk RNAP bind to the promoter

A

general transcription factors

29
Q

______ is a downstream promoter element and is most common when TATA is missing

A

DPE

30
Q

_____ is the initiator element

A

Inr

31
Q

_____ is the TFII recognition element

A

BRE

32
Q

RNAPII cnat bind by itself and needs a what ?

A

general transcription factor

33
Q

_____ is surrounded by a GC-rich region and is the only upstream promoter with a fixed location

A

TATA box

34
Q

does eukaryotic RNAP also need to pause?

A

yes

35
Q

_____ is a TF kinase that phosphorylates CTD of RNAPII to activate elongation

A

P-TEFb

36
Q

what catalyzes eukaryotic RNAP termination?

A

Cleavage and polyadenylation complex (CPA) recognizing Poly A signal (this dephosphorylates RNAP)

37
Q

what are some euk RNA modifications?

A

-5’ cap
-3’ tail
-splicing

38
Q

what is a 5’ cap and whats its function?

A
  • addition of methylated G7
  • protects 5’ mRNA
  • allows for proper ribosome positioning
  • helps with export to cytoplasm
  • promotes intron excising
39
Q

what does the Poly-A tail do?

A
  • gives mRNA stability
    -facilitates export to cytoplasm
    -helps with ribosome positioning
40
Q

what shows that an RNA is mature?

A

having a 5’cap, 3’ tail, and introns cut out

41
Q

what are the 2 types of splicing?

A

lariat, transesterification

42
Q

_______ make up spliceosomes that help process nuclear mRNA (introns removed in lariat pattern)

A

SNRPS

43
Q

_______ can produce a diversity of mRNAs from a single gene by arranging coding sequences

A

alternative splicing

44
Q

______- is transcribed as a 45S transcript by RNAPI in the nucleus

A

rRNA

45
Q

______ is processed as a 100nucleotide precursor by RNAPIII and is processed and modified before mature

A

tRNA

46
Q

RNAP binding at promoters may require ________

A

transcriptional factors

47
Q

promoters contain ____ elements and sequence for specifying tissue specificity

A

cis

601 EXAM 2 (11 decks)

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