Gene Expression Flashcards

1
Q

How is gene expression controlled in eukaryotics?

A

Transcription factors altering the rate of transcription of genes

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2
Q

What are transcription factors?

A

Proteins that bind to DNA and activate/deactivate genes

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3
Q

What are the two types of transcription factor in eukaryotes?

A
  • Activators

- Repressors

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4
Q

What do activators do? 2

A
  • Increase rate of transcription

- Help RNA polymerase bind to DNA

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5
Q

What do repressors do? 2

A
  • Decrease rate of transcription

- Prevents RNA polyermase binding to DNA

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6
Q

Where do transcription factors bind?

A

Start of target genes at specific DNA sites

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7
Q

What does an operon contain?

A
  • Structural genes
  • Control elements [promoter/operator]
  • Regulatory gene
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8
Q

What type of cell contains operons?

A

Prokaryotes

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9
Q

What are structural genes?

A

Genes coding for useful proteins functioning in cells

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10
Q

What is the promoter region?

A

DNA sequence located before the structural genes RNA polymerase binds to

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11
Q

What is the operator region?

A

DNA sequence transcription factors bind to

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12
Q

What is the regulatory gene?

A

Transcription factors coding for the expression of other genes : activators/repressors

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13
Q

What bacterium has the lac operon?

A

E.Coli

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14
Q

What is the lac operon?

A

The section of DNA where the enzymes needed for digesting lactose are found

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15
Q

What are 3 structural genes in the lac operon?

A
  • Lac Z
  • Lac A
  • Lac Y
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16
Q

What do 3 the structural genes in the lac operon code for?

A
  • Beta galactosidase

- Lactose Permease

17
Q

What are beta galactosidase and lactose permease?

A

Proteins helping bacteria digest lactose

18
Q

What is the regulatory gene in the lac operon called?

A

Lac I

19
Q

What happens when lactose is absent?

A
  • Regulatory gene [lacI] produces lac repressor protein
  • Binds to the operator site
  • Stops RNA polymerase binding to promoter region
  • No transcription of structural genes
20
Q

What happens when lactose is present?

A
  • Lactose binds to repressor protein
  • It changes shape
  • Can no longer bind to operator
  • RNA polymerase can bind to promoter region
  • Structural genes are transcribed and translated
  • Beta galactosidase and lactose permease are made