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BSCI330 SPRING > exam 2 control of gene expression PT regulation > Flashcards

exam 2 control of gene expression PT regulation Flashcards

1
Q

what can small non-coding RNAs do

A

regulate gene expression

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2
Q

what PTMs regulate protein function

A

activation/de-activation, co-localization with interacting molecules, assembly into multi-protein complexes

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3
Q

what can protein level be regulated by

A

ubiquitin/proteasome-mediated degradation

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4
Q

what does phosphorylation do

A

converts an inactive form into an active form and vice versa

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5
Q

what are molecular integraors

A

transcription factors have multiple sites for phosphorylation and other modifications

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6
Q

is the GTP-bound form activated or inactivated

A

activated

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7
Q

what does Ras do

A

phosphorylates and activates first kinase in cascade, which amplifies signal

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8
Q

what does the final map kinase do

A

prosphorylates Elk, which induces transcription and moves into nucleus to continue kinase cascade of phosphorylating things on and on

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9
Q

how do PTM regulate TF activity

A

changes cellular localization

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10
Q

what are the varsity of TFs

A

NF-AT and NF-kappaB

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11
Q

what happens with NF-AT and NF-kappaB

A

regulated by localization: held in cytosol inactive, then PTMs lead release and translocation to nucleus, where nuclear TF is able to regulate gene transcription

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12
Q

what is the self-regulating TF

A

NF-kappaB - induces transcription once in nucleus

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13
Q

what can combinatorial control generate

A

patterns during animal development

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14
Q

what is even-skipped expression

A

even segments are all missing when mutated - expression in one stripe is directed by one DNA molecule

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15
Q

what are positive transcription factors

A

where gene is expressed

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16
Q

what are negative transcription factors

A

boundaries of expression

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17
Q

how do different cell types arise to be able to express different TF patterns

A
  • cells in different places in an embryo can sense their locations and activate/express different TFs
  • during development, cells can receive different soluble signals that direct TF expression/activation
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18
Q

where can RNA levels be regulated at

A

level of initiation or termination

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19
Q

what does transcriptional attenuation lead to

A

premature termination of the RNA transcript

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20
Q

what does a growing RNA chain adopt through transcriptional attenuation

A

conformation that interferes with RNA polymerase activity - RNA pol pauses and aborts transcription

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21
Q

how can transcriptional attenuation be reversed

A

by binding of specific proteins to the RNA structure, allowing RNA pol to complete transcription

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22
Q

what are most eukaryotic genes regulated by

A

alternative splicing

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23
Q

what are splice variants

A

a gene with even just a few exons can produce many different mRNAs via alternative splicing

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24
Q

how does HIV use regulated nuclear export

A

to allow RNA molecules containing some introns to be exported from the nucleus

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25
Q

how can cells use regulated cytosolic localization

A

to place specific mRNAs at specific locations in the cell, allowing mRNAs and encoded proteins to be concentrated in a particular part of the cell

26
Q

how are genes regulated by mRNA stability

A

mRNA is rapidly degraded under certain conditions

27
Q

what does aconitase do

A

iron-binding protein

28
Q

what does endonuclease do

A

cleaves RNA, leading to degradation = no transferrin made

29
Q

what happens with high levels of iron

A

want ferritin, don’t want transferrin

30
Q

what happens with low levels of iron

A

want more transferrin and no ferritin

31
Q

what is ferritin

A

binds to iron in cell to keep it protected

32
Q

what is transferrin

A

imports iron in cell

33
Q

what forms the RNA-induced silencing complex (RISC)

A

a short double-stranded RNA is generated after processing and associates with a set of proteins

34
Q

what do miRNAs fold into

A

hairpin stem-loop structures

35
Q

what happens with the hairpin structure

A

one strand of RNA is degraded and the other makes base-pairing contacts with an mRNA target

36
Q

what does dicer do

A

cleaves off loop part of hairpin structure

37
Q

once RNA is sliced, how is it unstable and rapidly degrading

A

one half has 5’-cap, no poly-A tail and vice versa

38
Q

what do siRNAs do

A

mediate the process of RNA interference

39
Q

how is dsRNAs formed

A

formed by base-pairing between complementary regions of separate RNA strands

40
Q

what does dsRNA do

A

cleaved by dicer nuclease to form siRNA

41
Q

what does siRNA associate with

A

proteins to form RISC, and target mRNAs are cleaved

42
Q

how does siRNA form RITS complex

A

associated with different set of proteins

43
Q

what is the RITS complex

A

inhibits gene transcription by modifying chromatin structure

44
Q

what is dsRNA recognized by

A

dicer complex and is used to cut up siRNAs to form RITS

45
Q

what advantages might come from post-transcriptional regulation

A

can respond to environmental stimuli more rapidly than transcriptional regulation
- have protein - can quickly turn it on and off when you need it

46
Q

what can info in the 5’ and 3’ untranslated regions (UTRs) regulate

A

translation efficiency and mRNA stability

47
Q

what blocks ribosome access

A

5’ UTR RNA structure

48
Q

what inhibits ribosome scanning

A

RNA structure

49
Q

what can switch translation on and off

A

riboswitch structure using binding of an ion or small molecule

50
Q

what is required for efficient translation initation

A

repressors binding to 3’ UTR can prevent communication between 5’ and 3’ ends of mRNA

51
Q

what can phosphorylation of initiation factor eIF2 do

A

inhibit global protein synthesis by activating eIF2B, a translation initiation inhibitor

52
Q

what does eIF2 use

A

GTPase motif to mediate binding of initiator met-tRNA to small ribosomal subunit

53
Q

what is eIF2B

A

GEF that catalyzes exchange of GDP to GTP, activating eIF2

54
Q

what happens in absence of active eIF2B

A

excess eIF2 remins in its inactive, GDP-bound form and protein synthesis slows dramatically

55
Q

what does IRES (internal ribosome entry sites) allow for

A

ribosomes to skip the first AUG, which allows two different protein sequences to be derived from a single mRNA

56
Q

what is required for secreted/transmembrane proteins

A

different initiation sites leading to skipping of signal sequence, switching between cytosolic and secreted form of a protein

57
Q

what allows for independent simultaneous translation of two completely different proteins from one mRNA

A

IRES sitting between two separate ORFs

58
Q

what is protein turnover

A

another point of regulation

59
Q

why must damaged/mis-folded proteins be destroyed

A

to prevent accumulation of malfunctioning proteins

60
Q

what does ubiquitin/proteasome system allow for

A

regulated destruction of proteins

  • targeted protein is polyubiquitylated
  • proteasome recognizes polyubiquitylated protein and degrades it into short peptides

BSCI330 SPRING (24 decks)

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