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MAMS BCH Exam III > Offner RNA > Flashcards

Offner RNA Flashcards

(54 cards)

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1
Q

Difference in RNA processing for eukaryotes vs prokaryotes

A

Prokaryotes have no compartments for processing, eukaryotes do

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2
Q

What % of RNA is tRNA, rRNA and mRNA

A

95% tRNA, rRNA
1-5% mRNA

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3
Q

The template strand is the coding or non-coding strand

A

Non-coding

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4
Q

Structure of prokaryotic RNA Pol

A
  • beta subunit
  • sigma subunit
  • core enzyme: alpha2, beta, beta’

Prokaryotes

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5
Q

Structure of RNA Pol holoenzyme

A

alpha2, beta, beta’, sigma

Prokaryotes

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6
Q

Beta subunit of prokaryotic RNA Pol

A

Contains catalytic site
- synthesizes 3’-5’ phosphodiester bonds

Prokaryotes

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7
Q

Sigma subunit of prokaryotic RNA Pol

A

Recognizes promoter regions
- initiates transcription
- binds -10, -35

Prokaryotes

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8
Q

Does bacterial transcription require a primer?

A

Nahh bb

Prokaryotes

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9
Q

Where is the prokaryotic promoter region written, and what two sequences does it consist of?

A

On the sense strand
- non-transcribed strand
- coding strand
consists of -35 and -10

Prokaryotes

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10
Q

-35 region sequence

A

TTGACA

Prokaryotes

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11
Q

Pribnow sequence (-10)

A

TATAAT

Prokaryotes

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12
Q

What is the importance of the distance between the Pribnow and -35 region

A

Allows for the efficient intiation of transcription

Prokaryotes

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13
Q

How does prokaryotic transcription start

A

The core binds to random promoter and non-promoter regions
- sigma binds core, if bound to non-promoter, RNA Pol released
- holoenzyme opens DNA 12bp

Prokaryotes

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14
Q

2 different NT binding sites of beta subunit of RNA Pol

A

1st for Purine
- creates different phosphodiester bond
2nd for all subsequent dNTPs

Prokaryotes

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15
Q

Rho-independent termination

A

RNA Pol slows down in GC-rich palindrome region
- Hairpin forms, NRA released due to weak following A/U bonds
- must end with UUUUU region

Prokaryotes

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16
Q

Rho-dependent termination

A

Rho contains helices, ATPase
- Rho waits for RNA Pol to slow down
- Rho moves to 3’ end of RNA by hydrolyzing ATP
- unwinds DNA/RNA to release RNA

Prokaryotes

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17
Q

Actinomycin D

A

Initiation and elongation inhibitor
- intercalates in major groove to prevent unwinding
- effective in both prok and euk
- also doxorubicin

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18
Q

3 eukaryotic polymerases

A

1) RNA Pol I
2) RNA Pol II
3) RNA Pol III

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19
Q

Which RNA Pol transcribes tRNAs?

A

RNA Pol III

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20
Q

Which RNA Pol transcribes mRNAs?

A

RNA Pol II

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21
Q

Which RNA Pol transcribes miRNAs, snRNAs?

A

RNA Pol II

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22
Q

Which RNA Pol transcribes the rRNA for the 4 subunits?

Study These Flashcards
A

RNA Pol I: 28s, 18s, 5.8s
RNA Pol III: 5s

23
Q

Where are RNA Pol 1,2,3 located?

Study These Flashcards
A

RNA Pol I in nucleolus
RNA Pol II and III in nucleus

24
Q

Which RNA Pol transcribes small RNAs

25
RNA Pol II structure
12 subunits - core promoter binds to 3 regions
26
3 regions core promoter binds to
Basal (site of transcription initiation) , Constitutive (rate), Inducible (response to environmental elements)
27
Where is the enhancer region located
Anywhere upstream of the core promoter
28
Does formation of the basal transcription complex require ATP?
Yes, requires ATP hydrolysis
29
Components of the basal transcription complex
TBP TAF TFII (A,B,F,E,H)
30
TBP
TATA box binding protein
31
TAF
TATA associated factors
32
TFII
Transcription factors for Pol II
33
Which kinase phosphorylates Pol II
TFII H
34
How does eukaryotic transcription elongation start?
TFIIF and Pol II detach from the basal transcription complex
35
What occurs during termination
Dephosphorylation of Pol II and TFII F complex
36
Initiation of RNA Pol I
UBF and CBF combine to causes a conformational change in the DNA which allows RNA Pol I to bind and initiate transcription | UBF = Upstream Binding Factor CBF = Core Binding Factor
37
Initiation of RNA Pol III
Starts on internal promoter (within the gene) - TFIII B binds upstream, C and A bind by the +1 - Pol III binds, TFIIII C/A release, transcription initiated
38
Amanita Phalloides contains alpha-amanitin. Why is it dangerous?
Present in eukaryotes only - Fully inhibits RNA Pol II, and inhibits RNA Pol III a little - no mRNA, no proteins, liver failure, death!
39
What is hnRNA
mRNA without any modifications
40
Where do mRNA modifications take place
Nucleus, required for exit into the cytoplasm
41
mRNA 5' cap
Backwards GTP added to 5' end - 5'5' tri-P linkage - 2 from mRNA attach to one on GTP
42
Guanylyl Transferase
Removes gamma P from RNA and PPi from reversed GTP to add 5' cap to mRNA
43
3' polyA tail
specific endonuclease cleaves 11-30 NTs downstream of AAUAAA signal region - PolyA polymerase hydrolyzes ATP and adds 200 A residues to mRNA
44
Splicing mechanism
1) U1 RNA base pairs with 5' splice junction 2) U2 binds branch site 3) U4/5/6 bind to bring intron 1 splice site near branch point 4) U1/4 leave, U6 binds to U2 5) 2' OH of A attacks 5' splice site 6) 3' OH of exon 1 attacks 3' splice site 7) exons are joined, intron leaves
45
Why does splicing occur
Different sets of RNA binding proteins in different tissues
46
How does Thalassemia occur
A new 3' splice site results from point mutation - stop codon brought forward - truncated protein
47
How is tRNA produced in prokaryotes
As multimers - cleaved by RNAses at 5' and 3' ends - bases get modified - CCA added to 3' end by tRNA nucleotidyl transferase
48
How is tRNA produced in eukaryotes
Monomeric - contains intron to prevent premature mRNA binding - removed by endonuclease and ATP-dependent ligation
49
How do the ribosomal subunits assemble
Self-assemble
50
Mechanism by which eukaryotic ribosomes are formed
Precursor is spliced to 45S, which self-splices to 28S, 18S, and 5.8S - 28S, 5.8S and 5S combine to make large subunit (60s) - 18S becomes 40S - small and large subunits enter cytoplasm separately - 5S comes from RNA Pol III | Small and large subunits only combine if they are actively transcribing
51
Prokaryotic ribosome combos
25 + 5 = 50 16 = 30 Total = 70S
52
Eukaryotic ribosome combos
28:5.8 + 5S = 60 18 = 40 Total = 80S
53
Structure of rRNA precursor
one of each subunit rRNA
54
Where do all the eukaryotic rRNA precursors combine to make the large and small subunits?
Nucleolus

MAMS BCH Exam III (12 decks)

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