3.8.2.2 Regulation of transcription and translation (C20)

Question 1

Molecules which regulate the expression of genes are called..

Answer 1

transcription factors

Question 2

Where do transcription factors bind to regulate gene expression?

Answer 2

(upstream of the gene) Promoter region

Question 3

What do transcription factors do to regulate gene expression?

Answer 3

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

Question 4

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

Answer 4

moves from the cytoplasm to the nucleus

Question 5

Can specialised cells change into other cell types?

Answer 5

Housekeeping genes e.g. genes involved in respiration

Question 6

Name a hormone that can regulate transcription

Answer 6

oestrogen

Question 7

What type of hormone is oestrogen?

Answer 7

steroid hormone

Question 8

How can oestrogen enter the cell?

Answer 8

lipid soluble and diffused through the phospholipid bilayer

Question 9

Transcription is when

Answer 9

DNA is copied into mRNA

Question 10

Translation is when

Answer 10

mRNA is translated into a sequence of amino acids

Question 11

What does oestrogen bind to to regulate transcription?

Answer 11

Complementary receptor site on the transcription factor

Question 12

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

Answer 12

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

Question 13

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

Answer 13

oestrogen has a complementary shape the the receptor

Question 14

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

Answer 14

lipid soluble

Question 15

Who proposed the structure of DNA?

Answer 15

Watson and Crick

Question 16

What is meant by epigenetics?

Answer 16

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

Question 17

What sort of environmental factors might influence phenotype?

Answer 17

stress, sunlight, chemical exposure, diet,

Question 18

How is your DNA organised into chromosomes?

Answer 18

DNA wrapped around proteins called histones (forming chromatin)

Question 19

DNA and histones are covered in chemicals known as ..

Answer 19

tags

Question 20

Give examples of DNA tags

Answer 20

Methylation

Acetylation

(Phosphorylation)

Question 21

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

Answer 21

the epigenome

Question 22

What determines the shape of the DNA and histone complex?

Answer 22

epigenome

Question 23

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

Answer 23

gene silencing

Question 24

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

Answer 24

gene activation/expression

Question 25

DNA code is fixed but your epigenome is...

Answer 25

flexible

Question 26

What does your epigenome respond to?

Answer 26

the environment

Question 27

Tags attached to DNA are knowns as

Answer 27

methylation acetylation

Question 28

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

Answer 28

transcription factors can access the DNA and turn ON a gene

Question 29

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

Answer 29

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

Question 30

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

Answer 30

decreased acteylation and increased methylation

Question 31

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

Answer 31

increased acteylation and decreased methylation

Question 32

What does decreased acetylation do to the histone proteins?

Answer 32

increased + charge so more strongly attracted to phosphate in DNA

Question 33

Why does methylation prevent transcription?

Answer 33

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

Question 34

increased gene expression is brought about by

Answer 34

more acetylation and less methylation

Question 35

reduced gene expression is brought about by

Answer 35

less acetylation and more methylation

Question 36

acetyl group binds to

Answer 36

histones

Question 37

methyl group binds to

Answer 37

DNA

Question 38

more acetylation causes...

Answer 38

increased gene expression/DNA loosely packed

Question 39

MORE methylation causes...

Answer 39

reduced gene expression/DNA tightly packed

Question 40

LESS acetylation causes

Answer 40

reduced gene expression/DNA tightly packed

Question 41

LESS methylation causes

Answer 41

increased gene expression/DNA loosely packed

Question 42

epigenetics has been associated with what type of disease

Answer 42

cancer

Question 43

do epigenetic changes alter the DNA base sequence?

Answer 43

NO

Question 44

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

Answer 44

mRNA is cut up to prevent it being translated

Question 45

what type of molecule is involved in silencing mRNA?

Answer 45

siRNA

Question 46

Once siRNA is formed what does it associate with?

Answer 46

an enzyme

Question 47

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

Answer 47

Their base sequences are complementary

Question 48

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

Answer 48

less acetylation - reduced gene expression (mRNA not transcribed)

Question 49

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

Answer 49

tightly packed

Question 50

How do transcription factors move?

Answer 50

from the cytoplasm to the nucleus

Question 51

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

Answer 51

oestrogen

Question 52

can epigenetic changes be inherited?

Answer 52

yes!