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Molecular Exam 3 > Control of Gene Expression 2: Post transcriptional control > Flashcards

Control of Gene Expression 2: Post transcriptional control Flashcards

1
Q

RNA splicing can be regulated negatively by what? and what does it do?

A

repressor molecule that prevents splicing machinery access to splice sites

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2
Q

How can RNA splicing be regulated positively? and how?

A

by activating molecule that recruits and helps direct splicing machinery

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3
Q

What do mRNAs have to confer stability?

A

poly A tail

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4
Q

What are the steps in regulation by RNA stability?

A
  1. decapping: exposed mRNA degraded from 5’ end

2. mRNA degraded from 3’ end through poly-A tail and into coding region

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5
Q

What does ferritin mRNA do?

A

storage of iron

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6
Q

what does TfR mRNA do?

A

iron absorbance

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7
Q

Describe ferritin

A

intracellular protein
binds thousands of Fe 3+/molecule
found in most cells

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8
Q

What is hemosiderin?

A

granules of ferritin

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9
Q

Where is excess of iron stored?

A

liver
lungs
pancreas

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10
Q

What happens during iron starvation?

A

decrease ferritin mRNA (encodes storage of protein)
cells must transport iron into cells
make more transferrin receptor (TfR) mRNA

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11
Q

What happens during iron in excess?

A

make more ferritin mRNA
transport less iron out of the cell
make less TfR mRNA

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12
Q

What are iron responsive elements (IREs)

A

recognition sites for binding

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13
Q

What are iron responsive regulatory protein (IRP)

A

aconitase

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14
Q

What happens when IRP binds to IRE at 5’ ferritin mRNA

A

no ferritin- translation is blocked

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15
Q

What happens when IRP binds to IRE at 3’ transferrin receptor mRNA

A

transferrin receptor made-mRNA stable

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16
Q

What happens if IRP does not bind to IRE at 5’ ferritin mRNA

A

mRNA made- get ferritin

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17
Q

What happens if IRP does not bind to IRE at 3’ transferrin receptor mRNA

A

RNA degrades and no transferrin receptor made

18
Q

What are noncoding RNAs?

A

22 nucleotides long that silence expression of specific mRNA targets

19
Q

What are microRNAs?

A

regulatory RNAs that regulate messenger RNAs

20
Q

Are the changes in microRNA expression causative of disease or responsive to disease?

A

yes

21
Q

Causative

A

miRNAS likely to have mutations that cause the disease

22
Q

Responsive

A

increased miRNA expression down regulates genes in response to disease to limit severity

23
Q

What is found in the involvement of Tourettes syndrome?

A

1 form of miRNA, SLITRK1 variant

24
Q

What happens if there is a change in recognition sequence on target SLITRK1 mRNA?

A

increased miRNA binding

25
Q

What is required by proteins to be functional?

A

post translational modification

26
Q

What are proteins modified by?

A

protein kinase

27
Q

What is synthesized in dramatic amounts when the temperature is raised?

A

heat shock proteins (Hsp)

28
Q

Why are Hsp made dramatically when temp is raised?

A

increase in temperature leads to increase in misfolding proteins and the Hsp help with refolding

29
Q

What does the proteasome do?

A

removes misfolded proteins, deliberately destroys aberrant proteins

30
Q

How do you recognize a protein for destruction?

A

ubiquitin removes unfolded or abnormal proteins

31
Q

How does ubiquitin remove abnormal proteins?

A

with a recognition tag that marks them for destruction

32
Q

Proteasome inhibitors can be used to treat _________

A

multiple myelomas

33
Q

What is a myeloma?

A

cancer of plasma cells

34
Q

What is Bortezomib?

A

inhibitor of proteasome

35
Q

How does bortezomib world?

A

interacts with 1 proteolytic site-reversibly inhibits proteasome

36
Q

What are four controls of gene expression?

A
  1. coordinated expression of genes: genes don’t exist in a vacuum
  2. decision for specialization: what kind of cell do I want to be?
  3. Methylation and genomic imprinting: what genes get expressed (or not) from mom and dad
  4. X chromosome inactivation: even things out XX vs XY
37
Q

What is genomic imprinting?

A

differential expression of genetic material depending on the parent of origin

38
Q

What is epigenetic?

A

regulation of expression of gene activity without altering gene structure

39
Q

What causes Prader Willi (PWS) syndrome?

A

paternal deletion of chromosome 15 in the region 15q11-q13

40
Q

What are the stages of PWS?

A

stage one: infantile hypotonia; poor suck; feeding difficulties- failure to thrive
stage two: hyperphagia (uncontrollable eating), onset of early childhood obesity

41
Q

What is x inactivation?

A

In females, one of the X chromosomes becomes very condensed and turns into a Barr body, this chromosome is not expressed

42
Q

True or false? MicroRNAS bind to mRNAs to activate the mRNAs to produce large amounts of protein

A

False

Molecular Exam 3 (13 decks)

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