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Block 3 Biochem > Gene expression (THe deev) > Flashcards

Gene expression (THe deev) Flashcards

1
Q

What is a multistep process that ultimately results in the production of a functional gene product (either RNA or protein)

A

Gene expression

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2
Q

True/False: We all started by one single cell

A

True

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3
Q

What are involved in basic cellular functions that are required regardless of cell type or environmental cues. are constitutively expressed and not regulated

A

Housekeeping genes

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4
Q

What are required only in certain cell types and/or only under certain conditions. Various control mechanisms which determine if and when the genes will be expressed.

A

Regulated genes

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5
Q

What genes are only required under certain conditions?

e.g. Betactin(sp?), part of the cytoskeleton

A

Regulated genes

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6
Q

What are the two classifications of genes?

A

Housekeeping genes and regulated genes

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7
Q

True/False: Prokaryotic cells have nucleus and mitochondria.

A

False they don’t have nucleus or mitochondria
Pro- NO
Eu- DO

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8
Q

Is mRNA ready to be translated immediately after transcription?

A

Yes, in prokaryotic genome whatever is encoded in the mRNA it is ready to be translated into proteins via ribosomes.

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9
Q

Transcription happens in _______.

A

Nucleus

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10
Q

Translation happens in _______ via _______.

A

Cytosol via ribosomes

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11
Q

Is RNA ready to be translated into proteins immediately after transcription?

A

No, There is post-transcriptional, and post-translational control with eukaryotes.

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12
Q

After proteins come out of translation are proteins ready to go do their job?

A

No, they need to be modified or degraded usually in Golgi apparatus via post-translational modification.

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13
Q

What is another role of control…“around genetics”

A

Epigenetics

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14
Q

Prokaryotic gene expression involves two regulatory molecules, what are they and what do they do?

A

Repressors- suppress the transcription of a gene

Activators- increase the transcription of a gene

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15
Q

What does the operon contain?

A

Control region and structural genes

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16
Q

What is the goal of any organism?

A

conserve energy,

“no organism wants to make enzymes that are not useful for anything”

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17
Q

What are two types of operons?

A

Repressible- transcription is usually ON but can be inhibited (repressed)
Inducible- transcription is usually OFF but can be stimulated (induced)

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18
Q

What is the inducible operon that we talked about?

A

Lactose operon (Lac Operon)

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19
Q

What is the prefered carbon source for E. coli?

A

Glucose, but has capability to use other sugars like lactose (only if it is necessary)

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20
Q

With Lac Operon if only glucose is present, is the Lac Operon on or off?

A

OFF

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21
Q

What is encoded by lacl gene, always present and bound to the operator, blocks RNA polymerase

A

Repressor protein is ALWAYS expressed

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22
Q

When glucose is sufficient, what happens to the Lac Operon?

A

Lac Operon is off

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23
Q

When only lactose is present, (no glucose) what happens to the Lac Operon?

A

Lac Operon is on

24
Q

Glucose inhibits _____ ________, so there is no cAMP, cannot form CAP/cAMP complex , cannot initiate transcription

A

Adenylyl cyclase

25
Q

If both glucose and lactose are present what happens to the Lac Operon?

A

Lac Operon is off

26
Q

What are the 5 different levels of gene expression in Eukaryotes?

A 
(TPTPE)
Transcriptional
Posttranscriptional
Translational
Post-translational
Epigenetics
27
Q

Why do you need more levels of regulation?

A

We are more complex as eukaryotes

28
Q

What is the only similar level of control between eukaryotic DNA and Prokaryotic DNA?

A

Transcriptional control

29
Q

Why is transcriptional control just a little different between Eukaryotes and Prokaryotes?

A

EUK- usually one gene encodes for one protein

PROK- ???

30
Q

Influence expression of genes only on the same chromosome… only controls expression of genes that are downstream.

A

Cis-acting

31
Q

Where does transcriptional control take place?

A

Usually embedded in noncoding region of the genome

32
Q

Proteins are also called _______ regulators (transcription factors that interact with regulatory molecules).

A

Trans-acting

33
Q

Binding of trans-acting regulators (TF) to DNA is achieved by one of the following 3 things:

A

ZInc Finger
leucine zipper
helix-turn-helix in the protein

34
Q

What are DNA sequences that increase the rate of initiation of transcription.

A

Enhancers

35
Q

True/False: Enhancers are typically on different chromosomes.

A

False: typically on same chromosome

36
Q

What is the role of transcription factors?

A

DNA binding domain
Activation domain- stabilize formation of initiation complex recruit chromatin modifying proteins (i.e. histone acetylase)

37
Q

_______ is a _______ hormone that diffuses into hepatocytes to regulate PEPCK gene expression.

A

Cortisol, steroid

38
Q

True/False: Over 60% of ~25,000 genes in humans undergo alternative splicing.

A

True

39
Q

What is an actin filament-binding protein, which undergoes tissue specific alternative splicing to produce multiple isoforms of the protein?

A

Tropomyosin

40
Q

Apo B mRNA is made in the ______ and __________

A

liver and small intestine

41
Q

Additional posttranscriptional modification in which base in mRNA is altered.

A

mRNA editing (e.g. Apo B mRNA)

42
Q

The C residue in the CAA codon for glutamine is deaminated to U changing the sense codon to a ________ or _______.

A

nonsense or stop codon

43
Q

What is a mechanism of reducing gene expression by repressing translation or increasing degradation of specific mRNAs… (widely used in research and has a lot of potential)

A

RNA interference (RNAi)

44
Q

Neovascular AMD and VEGF lead to excess _____ ____ behind the retina. First clinical trial of RNAi for this helping macular degeneration.

A

blood vessels

45
Q

RNAi is mediated by very short RNA (~20-22bp) called ______.

A

microRNA (miRNA)

46
Q

miRNA acts as a _____ strand to target specific mRNAs that contain complementary sequence.

A

guide strand

47
Q

What are siRNAs?

A

double stranded short interfering RNAs (siRNAs) introduced into a cell to trigger RNA interference.

48
Q

What are mobile segments of DNA that move in a random manner from one site to another on the same or a different chromosome?

A

Transposons

49
Q

What are regions in DNA that are rich in CG that are prone to modifications.

A

CpG islands

50
Q

Phosphorylation of ___ inhibits GDP-GTP exchange and so inhibits translation at the initiation step.

A

elF-2

51
Q

When elF-2 is phosphorylated by kinases what happens?

A

Translation is blocked

52
Q

When elF-2 is not phosphorylated by kinases what happens?

A

Translation occurs

53
Q

What are the 4 modifications of polypeptide chain?

A

Trimming
Covalent attachments
Protein folding by chaperones
Protein degredation by ubiquitination

54
Q

Protein degredation happens by?

A

Ubiquitination

55
Q

Protein folding is directed by what?

A

Chaperones

56
Q

_______ is loosely packed and is accessible for transcription.

A

Euchromatin

57
Q

_______ is tightly packed and is inaccessible by transcription.

A

Heterochromatin

Block 3 Biochem (10 decks)

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