Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Biochem Block 3 > Gene Expression > Flashcards

Gene Expression Flashcards

1
Q

Gene expression

A
  • multi step process that ultimately result in the production of a functional gene product
  • RNA or protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Housekeeping genes

A
  • involved in basic cellular functions that are REQUIRED reguardless of the cell type or environmental cues
  • constitutively expressed and not regulated
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Regulated genes

A
  • required only in certain cell types and/or certain conditions
  • subject to control mechanisms
  • determine when and what genes are expressed
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

How many levels of regulation of gene expression do prokaryotes have?

A
  • 1
  • transcription only
  • DNA is transcribbed into mRNA then, directly into a protein
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How many levels of gene expression regulation are present in eukaryotes and what are they?

A
  • 5
  • transcriptional
  • post transcriptional
  • translation
  • post translation
  • epigenetics
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Epigenetics

A
  • nothing changes to DNA, just accessibility

- euchromatin and heterochromatin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Why are Eukaryotes more regulated than prokaryotes?

A
  • we have more differentiated types of cells

- transcription and translation are in different locations in eukaryotes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where does transcription, translation, and post-translational regulation occur in eukaryotes?

A

Transcription: nucleus
Translation: cytosol
Post-translation: golgi

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

transcription regulatory molecules for prokaryotes

A

-repressors and activators

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Repressor

A

-suppress the transcription of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Activator

A

-increase the transcription of a gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

repressible operon

A
  • transcription is usually on, but it can be repressed

- structural genes are on unless inhibited

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Inducible operon

A
  • transcription is usually OFF, but can be stimulated

- structural genes are usually off

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the two regions in an operon?

A

-control region and structural genes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Control region

A

-controls ALL genes in the structural region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Structural genes

A

-genes that are necessary for expression

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is the preferred carbon source for E. coli?

A

Glucose

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

When does E. coli use other sources?

A

ONLY if…

  1. glucose is absent
  2. another sugar is present(lactose)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why does E. coli prefer not to use other sources besides glucose?

A

-to use other sources, it must use more enzymes, which requires more energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Is the Lac Operon on or off when glucose only is present?

A

OFF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

repressor protein when glucose only is present?

A
  • encoded by the laclgene, always present and bound to the operator, blocks RNA polymerase
  • cannot transcribe gene
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

adneylyl cyclase when glucose only is present

A
  • glucose inhibits adenylyl cyclase
  • no cAMP
  • cannot form CAP/cAMP complex
  • cannot initiate transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Is the lac operon on or off when lactose only is present?

A

ON

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

adenylyl cyclase when lactose only is present

A
  • able to make cAMP
  • CAP/cAMP complex forms and binds to binding site
  • RNA polymerase CAN EFFICIENTLY INITIATE TRANSCRIPTION
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

allolactose

A
  • isomer of lactose

- when lactose is present, this is produced and binds to the repressor to prevent it from binding to the operator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

is Lac operon on of off when glucose AND lactose are present?

A

OFF

  • glucose inhibits adenylyl cyclase so no CAP complex to initiate transcription
  • lactose produces allolactose, which binds to the repressor, but if there is no CAP complex, it does not matter
  • no transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

is the transcriptional control from prokaryotes and eukaryotes the same?

A
  • nah bro

- the DNA structure is different, so they both do it, but its different

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Eukaryote transcriptional control

A
  • controlled by the regulatory sequences of DNA

- usually embedded in the noncoding regions of the genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Cis-acting

A
  • influence expression of genes only on the same chromosome
  • only control genes downstream from it
  • does not influence neighboring genes
  • regulatory seguence of DNA that control transcription of eukaryotes
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

trans-acting

A
  • transcription factors
  • proteins
  • interact with cis-acting regulatory sequences of DNA
  • no trans-acting=no transcription
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Binding of trans-acting regulators to DNA is achieved by one of the following…

A
  • zinc fingers
  • leucine zipper
  • helix-turn-helix in the protein
32
Q

Enhancers

A
  • DNA sequences that increase the rate of initiation of transcription
  • only recognize certain transcription factors
33
Q

Where are enhancers normally located?

A
  • typically on the SAME chromosome
  • gene and enhancer are on same chromosome
  • can be close to each other of thousands of base pairs away
  • can be upstream OR downstream or in intron regions
  • can act in tissue specific manner if the DNA binding proteins are only present in certain tissues
34
Q

how are enhancers brought closer to the basal promoter?

A

-by bending the DNA molecule

35
Q

Transcription factors

A
  • trans-acting molecules

- DNA binding domain

36
Q

Transcription factor activation domain

A
  • bind to other transcription factors
  • interact with RNA polymerase II to stabilize formation of the initiation complex and recruit chromatin modifying proteins
37
Q

PEPCK gene expression is induced by…

A

-cortisol

38
Q

PEPCK transcriptional control

A
  • cortisol diffuses into hepatocyte and binds to intracellular receptor
  • cortisol-receptor complex binds to glucocorticoid response element(in nucleus) to induce transcription of PEPCK
39
Q

cortisol

A
  • steroid hormone

- fat soluble

40
Q

post-transcriptional control types

A
  • alternative splicing
  • mRNA editing
  • mRNA stability
41
Q

alternative splicing

A
  • tissue specific isoforms of proteins can be made from the same pre-mRNA
  • make different isoforms
42
Q

how many genes in humans undergo alternative splicing?

A

60% of the 25000 genes

43
Q

tropomyosin

A
  • actin filament-binding protein
  • contraction of muscles, in cytoskeleton
  • undergoes alternative splicing
44
Q

mRNA editing

A

-additional posttranscriptional modification in which base in mRNA is altered

45
Q

Apo B mRNA in intestine

A
  • the C residue in the CAA codon for glutamine is deaminated to U
  • changes codon to a stop codon
  • results in a shorter protein
46
Q

which Apo B mRNA is in intestine and which is in liver?

A
  • Apo B 48 in intestine

- Apo B 100 in liver

47
Q

What does Apo B 48 mean?

A

48% of the message was coded

48
Q

RNA interference (RNAi) types

A
  • mechanism of reducing gene expression by…
  • repressing translation
  • increasing the degradation of specific mRNA
49
Q

Which type of RNA interference is more common?

A

-increasing the degradation of specific mRNA

50
Q

fundamental role of RNA interference

A

-cell proliferation, differentiation, apoptosis

51
Q

RNA interference and AMD

A
  • Neovascular AMD is triggered by over production of VEGF, leading to excess blood vessels behind retina
  • RNA interference in trials is trying to degrade VEGF and prevent the making of new blood vessels
52
Q

microRNA

A
  • miRNA
  • very short RNA(20 base pairs)
  • mediates RNAi
  • acts as a guide strand to traget specific mRNA that contain the complementary sequence
53
Q

RNAi mechanism

A
  • protein complex(RNA-induced silencing complex) works with miRNA
  • expression of gene is reduced by cleaving RNA or blocking translation
54
Q

siRNA

A
  • double stranded short interfering RNA
  • induced into a cell from an outside source can trigger RNAi
  • if you know the target, you know what to introduce to fix it
55
Q

translational control: elF-2 inhibition and promotion

A
  • promoted by dephosphorylation

- inhibited by phosphorylation

56
Q

phosphorylation of elF-2

A
  • inhibits elF-2 function by inhibiting GDP-GTP exchange
  • inhibits translation at the initiation step
  • catalyzed by KINASES that are activated in response to environmental conditions
57
Q

what environmental conditions activate kinases for phosphorylation of elF-2?

A
  • amino acid starvation
  • double stranded RNA
  • misfolded proteins in rough ER
58
Q

Post-translational control: modification of polypeptide chain

A
  • after the chain is formed
    involves. ..
  • trimming
  • covalent attachments
  • protein folding
  • protein degradation
59
Q

triming

A
  • post-translational control
  • they are initially synthesized as large precursors then cleaved to become functionally active
  • digestive proteins
60
Q

covalent attachments

A
  • post-translational control
  • phosphorylation
  • glycosylation
  • hydroxylation
  • many others
61
Q

protein folding

A

-directed by chaperones

62
Q

protein degradation

A
  • post-translational control
  • by ubiquitination
  • proteins target molecules to degrade them
63
Q

euchromatin

A
  • loosely packed DNA
  • less dense
  • accessible for transcription
64
Q

heterochromatin

A
  • tightly packed DNA
  • not easily accessible for transcription
  • more dense
65
Q

epigenetic regulation is modification in…

A
  • histones

- DNA

66
Q

CpG islands

A

-regions in NDA rich in CG that are prone to modification for epigenetics

67
Q

mechanisms of epigenetic reglation

A

-acetylation and methylation

68
Q

acetylation of histones

A
  • results in loose packing of DNA

- transcription factors can bind and transcription can go

69
Q

methylation of DNA and histones

A
  • makes nucleosomes pack tightly together

- less exposed, less accessible for transcription

70
Q

what can cause epigenetic changes>

A
  • development
  • diet
  • chemicals
  • drugs
  • aging
71
Q

epigenetic changes can result in…

A
  • cancer
  • autoimune disease
  • mental disorders
  • diabetes
72
Q

transposons(Tns)

A

-mobile segments of DNA that move in a random manner from one site to another on the same OR different chromosome

73
Q

movement of Tns is mediated by…

A
  • transponase

- enzyme encoded by Tn

74
Q

Direct movement of Tns

A
  • transponase cuts out and then inserts the Tn at a new site
  • cut and paste
75
Q

replicative movement of Tns

A

-Tn is copied and the copy is inserted elsewhere and original remains in place

76
Q

diseases associated with transpostion

A
  • hemophilia A
  • duchenne muscular dystrophy
  • can cause antibiotic resistance

Biochem Block 3 (10 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions