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Section 4 > Transcription/RNA processing > Flashcards

Transcription/RNA processing Flashcards

1
Q

What are 3 ways in which RNA differs from DNA?

A
  1. RNA does not contain thymine, but uracil instead.
  2. RNA is single-stranded
  3. RNA contains ribose (not deoxyribose)
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2
Q

Difference between RNA poly vs DNA poly? (2)

A
  1. RNA poly initiate RNA synthesis without a primer

2. more error prone then DNA

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3
Q

What are the 6 classes of RNA?

A
  1. mRNA
  2. rRNA
  3. tRNA
  4. snRNA
  5. snoRNAs
  6. other non-coding RNAs
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4
Q

What RNA functions to code for proteins?

A

mRNA

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5
Q

What RNA serves a number of functions in the nucleus, which includes pre-mRNA splicing?

A

snRNA

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6
Q

What RNA serves as components of the ribosome that are required for protein synthesis?

A

rRNA

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7
Q

What serves as adapters between mRNA and amino acids during protein synthesis?

A

tRNA

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8
Q

What serves to process and modify rRNAs?

A

snoRNAs

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9
Q

What types of functions do non-coding RNA’s have?

A

telomere synthesis
protein transport into the ER
transcriptional control

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10
Q

What is the poly for mRNA?

A

pol II

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11
Q

Poly for rRNA?

A

Pol I and poly III

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12
Q

Poly for tRNA?

A

Pol III

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13
Q

Poly for snRNA?

A

pol II and III

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14
Q

Poly for snoRNA?

A

pol II

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15
Q

Poly for other non coding RNAs?

A

pol III and II

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16
Q

What requires Pol II?

A

mRNA

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17
Q

What requires pol III?

A

tRNA

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18
Q

WHat requires Pol I and poly III?

A

rRNA

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19
Q

What requires pol II and pol III?

A

snRNA

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20
Q

Describe Pol I.

A

synthesizes rRNA; rRNA contains one copy of each of the four RrRNA molecules, 28S, 18S, 5.8S, and 5S.

Pol III makes some rRNA too

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21
Q

Describe Pol III.

A

responsible for rRNA but mainly tRNA. ( cells contain multiple copies of the gene for each tRNA, allowing sufficient quantities to be generated in a timely manner)

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22
Q

What transcribes the mRNA which is ultimately transcribed into proteins?

23
Q

TATA box, CAAT box and GC region are all considered what?

A

consensus sequences

24
Q

What is TFIID?

A

factors that are required in order to initiate transcription at the promotor

25
Steps of Pol II activation.
1. TFIID has TBP on it, and this TBP binds to the TATA box. 2. Binding causes a distortion and this causes TFIIE, F, and H to be recruited to the promotor. 3. this forms the transcriptional initiation complex. 4. TFIIH has DNA helicase activity, pulls apart, and Pol II begins to synthesize.
26
Promotors have lots of what type of bases in them?
A/T bases since it is easier to pull them apart (only 2 H bonds)
27
SP-1 binds to?
GC-rich regions
28
NF1 binds to?
CAAT box
29
What is an inhibitor of Pol II in humans?
death cap mushroom
30
What are the 3 steps of processing pre-mRNA?
1. capping 2. introns cut out 3. poly-a tail
31
Explain how capping works?
5' end of pre-mRNA modified
32
Explain the process of cutting out introns?
splicing is catalyzed by splicesosomes: 1. an adenine residue in the branch point of the intron attacks the 5' splice site, cutting the sugar phos backbone 2. cut 5' end gets covalently bonded to adenine, and forms a loops 3. newly generated 3' end of the exon reacts with the 5' end of the next exon
33
What allows for more than one protein product to be generated from a single pre-mRNA transcript?
splicing
34
Tropomyosin can be used for a specific topic in terms of splicing. What is it?
differential or alternate splicing: gives rise to a variety of different mRNA molecules
35
Explain how polyadenylation works?
1. 3' end of the RNA has a polyadenylation signal 2. signaled recognized by specific protein factors, and clevaged; 3. a poly-A tail is added
36
What are 2 things that are found in mRNA only?
5' cap, and 3' poly-A tail
37
What is one of the best characterized conditions that can result from incorrect splicing?
B-thalassemia
38
How does PKU result?
inability to convert phenylalanine to tyrosine; pts are found to have a single base change in the 5' splice donor site which leads to incorrectly spliced mRNA and a truncated protein that lacks one exon
39
What are 3 ways to regulate transcription in terms of gene availability?
1. Chromatin Remodeling Complexes: use ATP hydrolysis to change structure to a less tightly bound histone core 2. Histone Modification: HATS: increase; HDACS: decrease 3. DNA methylation: cytosine --> methylcytosine: silences
40
Where to DNA binding proteins bind to regulate transcription?
in the major groove because there are exposed poritons of bases
41
What are 3 classes of gene regulatory proteins?
1. helix-turn-helix 2. Zinc finger proteins 3. leucine zipper proteins
42
Explain helix-turn-helix
2 a-helices | side chains of the AA in the C-term of the 2 a-helix help with DNA binding
43
Explain zinc finger proteins.
zinc is coordinated in hisitidine and cysteine residues; zinc is required for protein folding and function
44
What is an example of a receptor that is a zinc-finger DNA binding protein?
glucocorticoid receptor
45
Explain leucine zipper proteins?
form dimers in which 2 a-helices form a coiled coil | -each a-helix contains a hydrophobic residue, typically a leucine, at every 7th position
46
What are 2 examples of leucine zippers?
Fos and Jun
47
Explain transcriptional regulation of the LDL receptor.
1. low cellular cholesterol 2. SP-1 binds GC-rich (requires CRSP as well) 3. SREBP-1a is outside the nucleus and comes in and binds to SRE-1 4. recruits a HAT, causing relaxation of chromatin, and LDL receptor gene transcription
48
What is often found in teh promotor of the glucocorticoid response genes?
GRE
49
What are 2 enzymes that are regulated by GRE?
PEP carboxykinase and liprotein lipase
50
Where are receptors for thyroid hormones found?
inside the nuclues
51
Explain regulation of thyroid hormone transcription.
No t3 bound: thyroid hormone receptor/RXR and HDAC T3 bound: THR, RXR, and HAT
52
EP300/CBP function as what?
HATS
53
How does Tamoxifen work?
it is a competitive inhibitor of estrogen for receptor binding; inability to recruit factors to initiate transcription

Section 4 (7 decks)

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