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eukaryotic gene expression Flashcards

1
Q

what is the primary purpose of gene control in multicellular organisms?

A

the execution of precise developmental programs
- so that the proper genes are expressed in the proper cells at the proper times (during embryologic development and cellular differentiation)

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2
Q

what is another name for epigenetic regulation?

A

chromatin-mediated regulation

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3
Q

where does transcription in eukaryotes take place?

A

on DNA that is wrapped in chromatin

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4
Q

what does the pioneer transcription factor required for?

A

unwinding and opening up DNA

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5
Q

Heterochromatin and how its packed

A
  • regions of chromosomes that are more intensely stained (densely packed)
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6
Q

what is heterochromatin rich in?

A

rich in repetitive DNA (transposons), centromeres and telomeres

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7
Q

what type of genes are found in heterochromatin

A

Inactive genes

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8
Q

Euchromatin

A

lightly strained chromosome regions

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9
Q

what type of genes are found in euchromatin?

A

Active genes

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10
Q

IMPORTANT
What does RNA polymerase I transcribe?

A

Pre-RNA (28S, 18S, 5.8S rRNAs)

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11
Q

IMPORTANT
What is the function of RNA polymerase I

A

Ribosome components, protein synthesis

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12
Q

IMPORTANT
what does RNA polymerase II transcribe? what are their functions?

A

mRNA (encodes proteins)
snRNAs (RNA splicing)
siRNAs (Chromatin-mediated repression, translation control)
miRNAs (translation control)

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13
Q

IMPORTANT
what does RNA polymerase III transcribe? what are their functions?

A
  • tRNAs (protein synthesis)
  • 5S rRNA (ribosome component, protein
    synthesis)
  • snRNA U6 (RNA splicing)
  • 7S RNA (signal recognition particle for insertion of polypeptides into the endoplasmic reticulum)
  • other small stable RNAs (various functions, unknown for many)
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14
Q

how many polypeptides are in RNA pol II? What are they called?

A
  • 12
  • RPB1-RPB12
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15
Q

true or false? all eukaryotic RNA polymerases share a very low level of homology with the yeast RNA pol II

A

false. - high level of homology

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16
Q

the clamp domain in the polymerase _______ accommodates ___ and then is ____ by a bridge

A

RPB1, DNA, closed

17
Q

how does the synthesized RNA exit?

A

through a channel

18
Q

eukaryotic RNA pol II contains a unique _______ of its RPB1 subunit

A

carboxy-terminal domain (CTD)

19
Q

what is the role of CTD

A

-involved in multiple regulatory interactions
key role in initiation, release, elongation and processing of the synthesized mRNAs

20
Q

what is the amino acid sequence of the CTD?
How many repeats are there? in mammals?

A
  • Tyr-Ser-Pro-Thr-Ser-Pro-Ser (The Sad Player Tried Some Pro Soccer)
  • contains 26 repeats
  • 52 repeats in mammals
21
Q

How are Ser residues in the CTD phosphorylated?

A

upon transition from initiation to elongation.

22
Q

In the RNA pol II structure, where does the RNA transcript come in?

A

in between the wall (on the left) and the clamp domain (on the right)

23
Q

what are the RNA polymerase II transcribed genes regulated by?

A
  1. conserved basal promoter elements, also called CORE PROMOTER SEQUENCES
  2. promoter-proximal binding sites for transcriptional activators
  3. distal enhancers or repressors
  4. chromatin structure
24
Q

where is the core promoter elements BRE and TFIIB located on pol II?

A

-37 to -32

25
Q

where is the TATA box located on pol II?

A

-31 to -26

26
Q

where is the Inr (Initiator) located on pol II?

A

-2 to +4

27
Q

where is the DPE (downstream promoter element) located on pol II?

A

+28 to +32

28
Q

which 3 elements direct the positioning of the polymerase?

A

TATA box, Initiator, BRE

29
Q

As the TATA box and Initiator start at a defined point on the coding strand. which TGCA does it bind to?

A

usually A

30
Q

where is the TATA box prevalent in?

A

highly transcribed genes

31
Q

Some genes contain an initiator but no TATA box. are initiator elements highly or poorly conserved?

A

poorly

32
Q

which recognition element does BRE known as?

A

TFIIB

33
Q

RNA polymerases must recognize the promoter and correctly initiate transcription at a very specific position. BUT THEY CAN NOT DO THIS ALONE. what other factors does this require help form?

A
  • several general pol II transcription factors (GTFs) assemble the pre initiation complex over the core promoter sequence
  • DNA helicase
34
Q

how does protein kinase help initiation of transcription?

A

release the polymerase

35
Q

how else do other factors help initiate transcription?

A

help the polymerase elongate
move nucleosomes out of the way

36
Q

what are the pol I GTFs

A

TFIA, TFIB

37
Q

what are the pol II GTFs

A

TFIIA, TFIIB, TFIID,TFIIE, TFIIH

mcb (10 decks)

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