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BIOL 115 > Gene regulation > Flashcards

Gene regulation Flashcards

1
Q

constitutive genes:

A

genes expressed all the time

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2
Q

regulated genes:

A

genes only expressed when needed

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3
Q

housekeeping proteins: and eg

A
  • proteins which are always needed

- ribosomal proteins

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4
Q

how does a cell regulate production of proteins:

A
  • feedback inhibition

- gene regulation

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5
Q

prokaryotes: feedback inhibition

A
  • activity of first enzyme in pathway stoped by end product
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6
Q

prokaryotes: gene regulation

A
  • gene coding for enzymes in metabolic pathway are controlled
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7
Q

prokaryotes: operon general features

A
  • prokaryote genes often arranged in operons
  • same genes under control of single promotor
  • all necessary proteins produced at same time in response to same stimulus
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8
Q

operons: list parts

A
  • operator
  • promoter
  • genes that they control
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9
Q

operons: operator

A
  • regulatory ‘switch’

- segment of DNA positioned within the promotor

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10
Q

operons: switched off by

A

protein repressor

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11
Q

operons: repressor

A
  • prevents gene transcription by binding to operator

- blocking RNA polymerase

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12
Q

operons: what codes for repressor protein

A
  • by regulatory gene

- located elsewhere in genome (co-repressor is tryptophan)

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13
Q

repressible operons:

A
  • usually on

- binding a repressor to operator will shit off transcription

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14
Q

repressible enzymes: function when

A
  • in anabolic (creating metabolites) pathways
  • synthesis repressed by high levels of end product
  • eg. tryptophan synthesis
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15
Q

inducible operons:

A
  • usually off

- inducer inactivates repressor to turn on transcription

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16
Q

inducible enzymes: function when

A
  • in catabolic (breaking down metabolic) pathways
  • synthesis induced by chemical signal
  • eg. lactose
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17
Q

lactose: general features

A
  • major sugar of milk
  • uncommon nutrient for bacteria
  • enzymes for lactose metabolism usually not expressed (conserve energy)
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18
Q

lactose: energy for cells

A
  • cells use glucose for energy

- lactose: disaccharide of glucose and galactose

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19
Q

lac operon: list enzymes involved

A
  • permease
  • b-galactosidase
  • transacetylase
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20
Q

lac operon: permease

A
  • allows lactose to enter bacterial cell
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21
Q

lac operon: b-galactosidase

A
  • breaks down lactose to glucose and galactose
22
Q

lac operon: transacetylase

A

unknown function, assists lactose breakdown

23
Q

lac operon: lac I

A
  • control gene
  • encodes lac repressor protein
  • when bound to DNA (operator) will prevent transcription at lac operon
24
Q

lac operon: inducer

A
  • form of lactose

- binds to repressor protein and inactivates it -> transcription of lac operon

25
Q

negative control:

A
  • both inducible and repressible operons involve negative control of genes (via repressor)
26
Q

positive control:

A
  • regulatory protein that switches transcription on

- eg. CRP activity in lac operon

27
Q

when is CRP inactive:

A
  • if glucose and lactose is present

- reduced expression of lac operon

28
Q

when is CRP active:

A
  • lactose present
  • no glucose
  • high levels of lac operon transcription
29
Q

eukaryotes: gene transcription

A
  • multiple control elements

- segments of noncoding DNA act as binding sites for transcription factors (help regulate transcription)

30
Q

eukaryotes: what are critical to precise regulation of gene expression in different cell types

A
  • control elements

- transcription factors

31
Q

proximal control elements:

A
  • located close to promotor
32
Q

distal control elements:

A
  • groupings of enhancers

- may be far away from a gene or even located in an intron

33
Q

where do transcription factors bind:

A
  • to TATA box within promoter/ other proteins/ transcription factors or RNA polymerase
34
Q

when does complete transcription occur:

A
  • when complete transcription initiation complex is assembled
  • eg. RNA polymerase and transcription factors
35
Q

how can some transcription factors also function as:

A

repressors

36
Q

an enhancer has:

A
  • 10 control elements
37
Q

control element:

A
  • binds 1-2 specific transcription factors
38
Q

combo of control elements important:

A
  • in transcription regulation
39
Q

coordinated transcription: features

A
  • unlike genes of prokaryotic operon, co-expressed eukaryotic genes have promoter and control elements
  • genes can be scattered over different chromosomes but each has same combo of control elements
40
Q

copies of activators recognise specific control elements and promote:

A

simultaneous transcription of the genes

41
Q

post-transcriptional regulation:

A
  • mRNA only codes for a protein-> the protein that carries out the function
42
Q

after transcription we can have:

A
  • alternative RNA splicing
  • block translation with regulatory proteins that prevent attachment of mRNA to ribosome
  • regulation of post-translational modification of protein
43
Q

cell differentiation:

A
  • process of cells becoming specialised in structure and function
44
Q

stem cell:

A
  • relatively unspecialised cell that can reproduce itself indefinitely and differentiate into specialised cells of one or more types
45
Q

embryonic stem cell:

A
  • isolated from early embryo which are able to differentiate into all cell types
46
Q

do adults have stem cells:

A
  • yes

- replace non-reproducing cells as needed

47
Q

totipotent stem cells:

A
  • obtained from early embryos, spores, plant calluses

- give rise to complete individual

48
Q

pluripotent stem cells:

A
  • give rise to many different cell types

- cannot produce entire individual

49
Q

multipotent stem cell:

A
  • gives rise to different cell types within tissues
50
Q

induces pluripotent stem cells (iPS):

A
  • potentially used to treat repair of damaged tissue in adults
  • using skin cells, reprogramming them
51
Q

proto-oncogene:

A

normal version of a gene

52
Q

oncogene:

A

cancer causing gene

BIOL 115 (23 decks)

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