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Biology 6.1.1: Cellular Control > gene regulation & transcription factors > Flashcards

gene regulation & transcription factors Flashcards

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1
Q

what is gene regulation?

A

the control of gene expression

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2
Q

how can the rate of transcription be changed?

A

turn it on / slow it down until turned off

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3
Q

what is an operon?

A
  • usually in prokaryotic cell
  • group of simultaneously controlled genes which are either all expressed or not
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4
Q

what is a promoter?

A
  • signal to start transcription
  • sequence of DNA
  • where RNA polymerase binds
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5
Q

what is an operator?

A

set of structural genes

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6
Q

define gene expression

A
  • conversion of the information encoded in a gene into a functional gene product
  • (usually a protein but sometimes just RNA)
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7
Q

describe the transcriptional level of regulation

A
  • transcription regulatory factors
  • regulation of gene expression during mRNA production
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8
Q

describe the post translational level of regulation

A

regulation of gene expression after protein synthesis
- addition of non protein groups
- folding/shortening of proteins
- modification of cAMP

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8
Q

describe the post transcriptional level of regulation

A

regulation of gene expression after mRNA production

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9
Q

what are transcription factors?

A

proteins which bind to DNA and increase/decrease transcription of genes

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10
Q

state and describe the two transcription factors

A
  • activators: speed up transcription
  • repressors: slow down transcription
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11
Q

how do transcription factors affect hormones/sugars?

A
  • they bind to the TF
  • increase or decrease binding to DNA
  • so the molecules present in a cell’s environment can control protein synthesis by TF binding
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12
Q

what is a transcription factor?

A

a protein molecule which binds to complementary base sequences, initiating or inhibiting transcription to control protein synthesis

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13
Q

summarise the process by which transcription factors initiate transcription

A
  • DNA binding site binds to complementary base sequence
  • this allows RNA polymerase to bind
  • transcription begins and creates the mRNA molecule for the gene, which can then be translated
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14
Q

why will a gene not bound to a transcription factor be inactive?

A

RNA polymerase cannot bind so transcription is inhibited

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15
Q

describe the movement of transcription factors

A

move from cytoplasm to nucleus

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16
Q

what is lac operon?

A
  • an operon present in e coli
  • sequence of 3 genes: lacZ, lacY and lacA
  • collectively aid digestion of lactose
17
Q

why is lac operon only needed if glucose isn’t present?

A
  • glucose requires less energy to be digested by bacteria so is the favourable respiratory substrate
  • if glucose isn’t present, lactose is digested
  • lac operon proteins are only needed if glucose is absent
  • this regulates transcription
18
Q

what is a repressor protein?

A

a protein that inhibits transcription

19
Q

what is lacL?

A

a regulatory gene near the operon which codes for a repressor protein

20
Q

how does lacL control transcription?

A
  • when lactose is absent, repressor is constantly produced
  • repressor binds to operator to prevent RNA polymerase binding at promoter
  • this inhibits transcription
  • when lactose is present, it binds to the repressor to change its shape
  • this prevents repressor binding to operator
  • allows RNA polymerase to bind to promoter
  • this initiates transcription
21
Q

what is the role of cyclic AMP (cAMP)?

A
  • increases rate of transcription for lac operon
  • because when transcription is initiated by repressor removal, it is still too slow to create required amount of enzymes
22
Q

what is the role of cAMP receptor protein (CRP)?

A
  • binds to lac operon to produce lacZ lacY and lacA
  • CRP only binds once bound to cAMP
23
Q

what are introns?

A

non coding regions

24
Q

what are exons?

A

coding regions

25
Q

all DNA of a gene, including introns and exons are transcribed to forma strand called ….

A

primary mRNA

26
Q

primary mRNA is edited during a process called ….. where the …. are removed, leaving only …. which are complementary to original ….

A

splicing
introns
RNA exons
DNA exons

27
Q

what is meant by epigenetics?

A

a heritable change in gene function without changing the DNA base sequence
- caused by the environment
- can inhibit transcription

28
Q

what two types of epigenetics prevent transcription?

A

increased methylation
decreased acetylation of histones

29
Q

how does increased methylation inhibit transcription?

A
  • methyl groups attach to cytosine bases
  • prevents transcription factors binding
  • attracts proteins that condense the DNA histone complex
30
Q

how does decreased acetylation inhibit transcription?

A
  • removal of acetyl groups increases positivity of histones
  • they are attracted to phosphate on DNA
  • DNA and histones strongly associate
  • makes it hard for transcription factors to bind
31
Q

what is splicing?

A

the removal of introns

32
Q

what is alternative splicing?

A

the concept that splicing occurs in many ways and allows a single gene to result in many proteins being created

33
Q

describe how genes are regulated after transcription

A
  • primary mRNA modified
  • introns removed
  • alternative splicing results in different versions of mRNA
  • binding of cAMP
34
Q

what makes a suitable respiratory substrate?

A
  • bonds that contain energy so can be broken
  • soluble so can move
  • H/OH groups that can bond with water molecules
35
Q
  • for lactose to enter cytoplasm, a protein is required
  • why are young mammals more likely to contain this protein in E coli than old mammals?
A
  • diet is high in milk - high lactose concentration
  • gene for the protein channel is switched on
36
Q

state 3 reasons fruit flies are chosen for genetic research

A
  • easy to obtain and keep a large sample
  • simple genetics
  • rapidly reproduce
37
Q

state 2 reasons mice are chosen for genetic research

A
  • similar to humans
  • easy to keep
38
Q

explain why some regions of DNA are described as non coding

A
  • introns removed
  • not present in mature mRNA
  • not translated
39
Q

suggest why non coding regions of DNA show more variation

A

doesn’t affect survival

Biology 6.1.1: Cellular Control (4 decks)

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