Regulation of Transcription and Translation Flashcards

1
Q

What are transcription factors?

A

A transcription factor is a protein that controls the transcription of genes by binding to a specific region of DNA.

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2
Q

Why are transcription factors needed?

A

They ensure that genes are being expressed in the correct cells, at the correct time and to the right level

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3
Q

Give 3 reasons why transcription is regulated.

A

To direct cell division, growth and death
To direct cell migration and organisation during embryonic development
Allow cells to respond to external signals

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4
Q

What is the 1st section of DNA involved in protein synthesis called?

A

Transcription unit

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5
Q

What does ‘upstream’ mean?

A

The DNA before the start of the coding region.

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6
Q

What 2 things bind to the promoter region in DNA?

A

RNA polymerase
Transcription factors

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7
Q

What direction is DNA transcribed in to produce mRNA?

A

5’ to 3’

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8
Q

What direction is DNA translated in to produce mRNA?

A

3’ to 5’

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9
Q

Explain the role of the promoter region in transcription.

A

RNA polymerase binds and 2 strands of the structural gene will unwind and unzip from the site of the polymerase binding.

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10
Q

Is the template or coding strand involved in transcription?

A

Template

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11
Q

What biomolecule are transcription factors made from?

A

Proteins

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12
Q

How do transcription factors enter the cell cytoplasm?

A

Through nuclear pores.

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13
Q

Where do transcription factors bind to on the gene?

A

Promoter region

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14
Q

What can transcription factors either cause or prevent?
How do they do this?

A

Transcription from taking place.
Transcription factors interact with RNA polymerase, either by assisting RNA polymerase binding to the gene (to stimulate expression of the gene) or by preventing it from binding (to inhibit gene expression)

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15
Q

What are steroid hormones?

A

Small hydrophobic lipid based hormones that can pass directly into the nucleus through nuclear pores.

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16
Q

Name the hormone that can act as a transcription factor.

A

Oestrogen

17
Q

What are ligand binding domains?

A

Binding sites that allow the factor to be responsive to an activating ligand.

18
Q
  1. Oestrogen stimulation pathway
    Describe how oestrogen enters the cell nucleus.
A

It diffuses through the cell cytoplasm and attaches enters the nucleus through pores.

19
Q
  1. Oestrogen stimulation pathway
    In the nucleus, what does the oestrogen attach to? What does this do to the thing it binds to?
A

An oestrogen receptor site. Binding leads to the receptor changing shape.

20
Q
  1. Oestrogen stimulation pathway
    What does the new shape of the oestrogen receptor allow the oestrogen to do?
A

Causes the oestrogen to detach and diffuse towards the gene being expressed.

21
Q
  1. Oestrogen stimulation pathway
    How does RNA polymerase become stimulated?
A

The ERα oestrogen receptor binds to a cofactor which enables it to bind to the promoter region of the gene, stimulating RNA polymerase binding and gene transcription.

22
Q

Explain why steroid hormones can rapidly enter a cell by passing through its cell surface membrane.

A

They are lipid soluble.
They can diffuse through the phospholipid bilayer.

23
Q

In cell cytoplasms, steroid hormones such as testosterone can bind to specific androgen receptors. Explain why.

A

Testosterone has a highly specific tertiary structure and can therefore bind to the receptor as it is complimentary.

24
Q

Binding of testosterone to androgen receptors changes its shape. The androgen receptor can then enter the nucleus and stimulate gene expression. Suggest how.

A

Androgen receptors could act as a transcription factor by binding to the DNA promoter region. This stimulates RNA polymerase.