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MCB2050 Part 1 > Overview of Eukaryotic Gene Expression > Flashcards

Overview of Eukaryotic Gene Expression Flashcards

1
Q

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

A

Ensure precise developmental programs so that the proper genes are expressed in the proper cells at the proper times.

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1
Q

Name the two scenarios where gene control takes place.

A

Embryologic development and cellular differentiation.

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2
Q

Transcription in eukaryotes takes place on DNA that is wrapped in ________.

A

Chromatin.

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3
Q

Chromatin needs to be open for two reasons. Name them.

A

For the gene to be activated and for transcription to proceed.

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4
Q

What is epigenetic regulation?

A

Chromatin-mediated regulation (entirely new mechanism compared to prokaryotes).

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5
Q

Describe heterochromatin.

A
  • Regions of chromosome that are more intensely stained.
  • DNA is more tightly packed.
  • It is rich in repetitive DNA (transposons), centromeres, and telomeres.
  • It is not accessible to transcriptional machinery.
  • Inactive genes are found here.
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6
Q

Describe euchromatin.

A
  • ‘Eu’ = True
  • Lightly stained chromosome regions
  • Active genes are found here
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7
Q

Describe euchromatin.

A
  • ‘Eu’ = True.
  • Lightly stained chromosome regions.
  • Active genes are found here.
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8
Q

Where are inactive genes found?

A

Heterochromatin.

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9
Q

Where are active genes found?

A

Euchromatin.

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10
Q

What kind of RNA is transcribed by RNA polymerase I?

A

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

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11
Q

What is the function of Pre-rRNA?

A

Ribosome components and protein synthesis.

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12
Q

What are the four kinds of RNAs transcribed by RNA Polymerase II?

A
  • mRNA
  • snRNAs
  • siRNAs
  • miRNAs
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13
Q

What is the function of mRNA?

A

Encode proteins.

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14
Q

What is the function of snRNAs?

A

RNA splicing.

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15
Q

What is the function of siRNAs?

A

Chromatin-mediated repression and translation control.

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16
Q

What is the function of miRNAs?

A

Translation control.

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17
Q

What are the five kinds of RNA polymerase transcribed by RNA polymerase III?

A
  • tRNAs
  • 5S rRNA
  • snRNA U6
  • 7S RNA
  • Other small stable RNAs
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18
Q

What is the function of tRNAs?

A

Protein synthesis.

19
Q

What is the function of 5S rRNA?

A

Ribosome component and protein synthesis.

20
Q

What is the function of snRNA U6?

A

RNA splicing.

21
Q

What is the function of 7S RNA?

A

Signal recognition particle for insertion of polypeptides into the endoplasmic reticulum.

22
Q

What is the function of ‘other small stable RNAs’?

A

Various functions, unknown for many.

23
Q

How many polypeptides are found in RNA pol II?

A

12 (RPB1-RPB12)

24
Q

True or false? Eukaryotic RNA polymerase share a very high level of homology with the yeast RNA pol II?

A

True.

25
Q

The clamp domain in the polymerase ________ accommodates DNA and then is closed by _______.

A

RPB1, a bridge.

26
Q

Where does the synthesized RNA exit through?

A

A “channel”.

27
Q

What is unique about the RPB1 subunit of RNA polymerase II?

A

It contains a carboxy-terminal domain (CTD). This is not found in any other polymerase, prokaryotic or eukaryotic.

Key role in initiation, release, elongation, and processing of the synthesized RNA.

28
Q

What is the role of the CTD (carboxy-terminal domain) found in RNA polymerase II of the RPB1 subunit?

A

Involved in many regulatory interactions and plays a key role in the initiation, release, elongation and processing of the synthesized mRNAs.

29
Q

What is the amino acid sequence of the CTD? How many repeats exist regularly? In mammals?

A

Tyr-Ser-Pro-Thr-Ser-Pro-Ser. 26 repeats. In mammals it is 52 repeats. (The Sad Player Tried Some Pro Soccer).

TSPTSPS

30
Q

What is the fate of the Ser residues in the CTD upon transition from initiation to elongation.

A

The Ser residues are phosphorylated.

31
Q

True or False? The CTD is structured and can be analyzed by crystallography?

A

False.

32
Q

List the four ways that RNA polymerase II transcribed genes are regulated?

A
  1. CONSERVED BASAL ELEMENTS (CORE PROMOTER SEQUENCES)
  2. Promoter proximal binding sites for transcriptional activators.
  3. Distal enhances or repressors.
  4. Chromatin structure.
33
Q

Name the position of the Core Promoter Element ‘BRE’

A

-37 to -32

34
Q

Name the position of the Core Promoter Element ‘TATA Box’

A

-31 to -26

35
Q

Name the position of the Core Promoter Element ‘Inr’ (Initiator)

A

-2 to +4

36
Q

Name the position of the Core Promoter Element ‘DPE’ (Downstream promoter element)

A

+28 to +32

37
Q

At promoters regulated by TATA box and initiator transcription starts at a defined point. Which TGCA does it usually bind to?

A

A

38
Q

Where is the TATA box prevalent in?

A

Highly transcribed genes.

39
Q

Some genes contain an initiator but no TATA box. Are these initiators highly or poorly conserved?

A

Poorly

40
Q

‘BRE’ is know as the TFII__ (A-H) Recognition Element

A

TFIIB

41
Q

RNA polymerases must recognize the promoter and correctly INITIATE transcription at a very specific point, however, it cannot do this alone. What does it require the help from?

A

General POLII Transcription Factors (GTFs).

42
Q

What do the GTFs assemble?

A

The preinitation complex over the core promoter sequences.

43
Q

True or False? Protein kinases release the polymerase?

A

True

44
Q

List the 2 types of RNA Pol I TFIs?

A

TFIA and TFIB (A,B)

45
Q

List the 5 types of RNA Pol 2 TFIIs?

A

TFIIA, TFIIB, TFIID, TFIIE, TFIIH (A,B,D,E,H)

46
Q

List the 2 types of RNA Pol 3 TFIIIs?

A

TFIIIB, TFIIIS (B,S)

MCB2050 Part 1 (13 decks)

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