TCOGE: Regulation of transcription

Question 1

Where do transcription factors move from and to?

Answer 1

From cytoplasm
To nucleus

Question 2

Each transcription factor has a _____ ____ that is complementary to a specific base sequence in the DNA.

Answer 2

binding site

Question 3

The binding site of a transcription factor can either be ____ or _____.

Answer 3

Active or inactive

Question 4

What does a transcription factor with an active binding site do?

Answer 4

Attaches to the complementary DNA base sequence and stimulates the transcription of that sequence.
This produces an mRNA strand which can be translated to produce a polypeptide.

Question 5

What does a transcription factor with an inactive binding site do?

Answer 5

Attaches to the complementary DNA base sequence and inhibits the transcription of that sequence.
This inhibits an mRNA strand from being produced which can be translated to produce a polypeptide.

Question 6

Transcription factors are important in the production of ______ ______ cells.

Answer 6

Induced pluripotent

Question 7

In the nucleus, DNA is wrapped around proteins called ______.

Answer 7

Histones

Question 8

What is gene expression determined by?

Answer 8

Shape of the DNA- histone complex.

Question 9

In areas where the DNA-histone complex is tightly packed, transcription is _______.

Answer 9

Inhibited

Question 10

When transcription is inhibited, genes are _______.

Answer 10

Inactive

Question 11

When transcription is stimulated, genes are _______.

Answer 11

Active

Question 12

In areas where the DNA-histone complex is loosely packed, transcription is _______.

Answer 12

Stimulated

Question 13

DNA and histones are covered in chemicals called _____ ____.

Answer 13

Chemical tags/epigenome

Question 14

Chemical tags are known as the ______.

Answer 14

Epigenome

Question 15

What does the epigenome do?

Answer 15

Determine the shape of the DNA-histone complex.

(this means that the DNA-histone complex will be tightly packed or loosely packed)

Question 16

The epigenome can be changed by _______ factors.

Answer 16

Environmental

Question 17

Name 3 environmental factors that can cause the epigenome to change:

Answer 17

• Stress
• Diet
• Exercise

Question 18

What do acetlyl groups bind to?

Answer 18

Histones

Question 19

What is acetylation?

Answer 19

The process of adding an acetyl group

Question 20

What does the acetylation of histones determine?

Answer 20

Transcription of genes.

Question 21

What happens when acetylation of histones increases? Explain why:

Answer 21

-Transcription is stimulated
- Acetyl groups are added to a particular histone, which loosens the DNA-histone complex *
- This means that more genes are exposed, so transcription is stimulated .

• (aka makes it move away from the clump of other histones)

Question 22

What happens when acetylation of histones decreases? Explain why:

Answer 22

• Transcription is inhibited.
• Acetyl groups are lost from a particular histone.
• This causes the DNA-histone complex to tighten. This means that more genes are hidden so transcription is inhibited.

Question 23

DNA has a phosphate backbone, which has a ______ charge.

Answer 23

Negative

Question 24

Histones contain a lot of amino acids which have ______ charged R groups.

Answer 24

Positively

Question 25

Where do acetyl groups bond to in histones?

Answer 25

The R group

Question 26

What happens to R groups when acetyl groups bond to them? How does this affect histone positioning?

Answer 26

- They remove the positive charge - This reduces the attraction between the phosphate backbone and the R group, resulting in DNA loosening from the histone.

Question 27

_____ groups bind to DNA wrapped around histones.

Answer 27

Methyl

Question 28

What is methylation?

Answer 28

The process of adding a methyl group

Question 29

What happens when methylation of DNA increases? Explain why:

Answer 29

- Transcription is inhibited - When methylation increases methyl groups are added to DNA, causing the DNA-histone complex to tighten. - The tightening means fewer genes are exposed, so transcription is inhibited.

Question 30

What happens when methylation of DNA decreases? Explain why:

Answer 30

- Transcription is stimulated - When methylation decreases methyl groups are lost from DNA, causing the DNA-histone complex to loosen. - The loosening means more genes are exposed, so transcription is stimulated.

Question 31

Methyl groups bind to _____.

Answer 31

DNA

Question 32

In DNA, methyl groups specifically bind to ______.

Answer 32

Cytosine

Question 33

Define epigenetics:

Answer 33

Heritable changes in gene function withtout changes to the base sequence of DNA.

Question 34

Changes to the epigenome are ______ inherited.

Answer 34

Sometimes

Question 35

Transcription of a gene could be inhibited by decreased _______ or increased ________ of the DNA-histone complex.

Answer 35

Acetylation Methylation

Question 36

One way in which epigenetic changes can be reversed is by developing drugs that target ______ that are responsible for adding or removing chemical tags.

Answer 36

Enzymes

Question 37

What roles do enzymes play in methylation/acetylation

Answer 37

Remove or add chemical tags

Question 38

Epigenetics impacts ________.

Answer 38

Translation