3.8.2.2 Regulation of transcription and translation (Unit 8 Gene Expression) Flashcards

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1
Q

Molecules which regulate the expression of genes are called..

A

transcription factors

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2
Q

Where do transcription factors bind to regulate gene expression?

A

(upstream of the gene) Promoter region

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3
Q

What do transcription factors do to regulate gene expression?

A

encourage binding of RNA polymerase (turn on genes) or prevent RNA polymerase binding (turn off genes)

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4
Q

When a cell receives a signal to express a gene what does the transcription factor do?

A

moves from the cytoplasm to the nucleus

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5
Q

Can specialised cells change into other cell types?

A

Housekeeping genes e.g. genes involved in respiration

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6
Q

Name a hormone that can regulate transcription

A

oestrogen

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7
Q

What type of hormone is oestrogen?

A

steroid hormone

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8
Q

How can oestrogen enter the cell?

A

lipid soluble and diffused through the phospholipid bilayer

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9
Q

Transcription is when

A

DNA is copied into mRNA

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10
Q

Translation is when

A

mRNA is translated into a sequence of amino acids

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11
Q

What does oestrogen bind to to regulate transcription?

A

Complementary receptor site on the transcription factor

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12
Q

When oestrogen binds to the receptor on the transcription factor what happens?

A

The DNA binding site changes shape on the transcription factor is now able to bind to DNA (transcription activated)

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13
Q

Why is oestrogen able to bind the receptor on transcrption factor?

A

oestrogen has a complementary shape the the receptor

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14
Q

What property of oestrogen allows it to diffuse through the phospholipid bilayer?

A

lipid soluble

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15
Q

Who proposed the structure of DNA?

A

Watson and Crick

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16
Q

What is meant by epigenetics?

A

heritable changes in gene function without change the base sequence of DNA

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17
Q

What sort of environmental factors might influence phenotype?

A

stress, sunlight, chemical exposure, diet,

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18
Q

How is your DNA organised into chromosomes?

A

DNA wrapped around proteins called histones (forming chromatin)

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19
Q

DNA and histones are covered in chemicals known as ..

A

tags

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20
Q

Give examples of DNA tags

A

Methylation

Acetylation

(Phosphorylation)

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21
Q

Tags attached to the DNA and histones form a second layer known as..

A

the epigenome

22
Q

What determines the shape of the DNA and histone complex?

A

epigenome

23
Q

DNA that is tightly packed, preventing transcription factors binding leads to

A

gene silencing

24
Q

DNA that is loosely packed, allowing transcription factors to access the DNA leads to…

A

gene activation/expression

25
Q

DNA code is fixed but your epigenome is…

A

flexible

26
Q

What does your epigenome respond to?

A

the environment

27
Q

Tags attached to DNA are knowns as

A

methylation

acetylation

28
Q

When the association of DNA and histones is weak what does this mean for gene expression?

A

transcription factors can access the DNA and turn ON a gene

29
Q

Tight association of DNA and histones affects gene expression - how?

A

prevents transcription factors binding to the DNA so turns OFF gene expression

30
Q

tight association of DNA and histones is brought about by..

A

decreased acteylation and increased methylation

31
Q

loose association of DNA and histones is brought about by..

A

increased acteylation and decreased methylation

32
Q

What does decreased acetylation do to the histone proteins?

A

increased + charge so more strongly attracted to phosphate in DNA

33
Q

Why does methylation prevent transcription?

A
  1. prevents transcription factors binding to DNA
  2. attracts proteins that would condense DNA
34
Q

increased gene expression is brought about by

A

more acetylation and less methylation

35
Q

reduced gene expression is brought about by

A

less acetylation and more methylation

36
Q

acetyl group binds to

A

histones

37
Q

methyl group binds to

A

DNA

38
Q

more acetylation causes…

A

increased gene expression/DNA loosely packed

39
Q

MORE methylation causes…

A

reduced gene expression/DNA tightly packed

40
Q

LESS acetylation causes

A

reduced gene expression/DNA tightly packed

41
Q

LESS methylation causes

A

increased gene expression/DNA loosely packed

42
Q

epigenetics has been associated with what type of disease

A

cancer

43
Q

do epigenetic changes alter the DNA base sequence?

A

NO

44
Q

Preventing gene expression can also be done at the level of mRNA - how?

A

mRNA is cut up to prevent it being translated

45
Q

what type of molecule is involved in silencing mRNA?

A

siRNA

46
Q

Once siRNA is formed what does it associate with?

A

an enzyme

47
Q

What is unique about the siRNA and the mRNA it is going to silence?

A

Their base sequences are complementary

48
Q

enzymes can remove acetyl groups - how would this affect transcription?

A

less acetylation - reduced gene expression (mRNA not transcribed)

49
Q

enzymes can remove acetyl groups - how would this affect DNA-histone complex?

A

tightly packed

50
Q

How do transcription factors move?

A

from the cytoplasm to the nucleus

51
Q

Expression of genes can be affected by other molecules e.g. hormones e.g. ….

A

oestrogen

52
Q

can epigenetic changes be inherited?

A

yes!