Gene Expression-Topic 8A

Question 1

When might gene mutations occur?

Answer 1

During DNA replication

Question 2

What is a mutation?

Answer 2

A change to the base (nucleotide) sequence of DNA

Question 3

What is Substitution?

Answer 3

One or more bases swapper e.g.

AT G C becomes AT T C

Question 4

What is Addition/ Insertion

Answer 4

One or more bases added so ACTG becomes ACATG

Question 5

What is Deletion?

Answer 5

One or more bases removed so

ACTG becomes CTG

Question 6

What is Duplication?

Answer 6

One or more bases repeated so ATGCCT becomes ATGCCCCT

Question 7

What is Inversion?

Answer 7

A sequence of bases is reversed e.g A TGCC T becomes A CCGT T

Question 8

What is Translocation? (type of mutation)

Answer 8

A sequence of bases is moved from one location in the genome to another (within same OR different chromosome)

Question 9

How is the rate of mutation increased?

Answer 9

Mutagenic agents

Question 10

Gene mutations occur ………

Answer 10

spontaneously

Question 11

Which types of mutations cause a frameshift?

Answer 11

Additions, duplications and deletions

Question 12

What is a frame shift?

Answer 12

a shift in the base triplets that mean that the triplet code is read in a different way.

Question 13

What is epigenetics?

Answer 13

Heritable changes in gene function caused by changes in environment without change to base sequence of DNA

Question 14

Ways that transcription is inhibited by:

Answer 14

increased methylation

decreased acetylation

Question 15

Describe the effect of decreased acetylation of histones on the transcription of genes they are associated with. [3]

Answer 15

Decreased acetylation = more highly condensed DNA-Histone complex
therefore transcription factor cannot access DNA
and DNA can’t be transcribed.

Question 16

What are totipotent cells?

Answer 16

Early embryonic stem cell that can divide and produce any type of body cell.

Question 17

What are pluripotent cells?

Answer 17

Pluripotent stem cells can divide in unlimited numbers and can be used in treating human disorders

Question 18

What are multipotent cells?

Answer 18

stem cells found in mature mammals and can divide to form a limited number of different cell types.

Question 19

What are unipotent cells?

Answer 19

stem cells found in mature mammals and can divide to form a limited number of different cell types.

Question 20

What are induced pluripotent cells? (iPS)

Answer 20

Induced pluripotent stem cells (iPS cells) can be produced from adult somatic cells using protein transcription factors

Question 21

Example of unipotent cells dividing into

Answer 21

cardiomyocytes (cells of heart)

Question 22

Explain how an activated oestrogen

receptor affects the target cell. [2]

Answer 22

Transcription factor binds to promoter region which stimulates RNA polymerase
which increases transcription

Question 23

Oestrogen only affects target cells. Explain why oestrogen does not affect other cells in the body. [1]

Answer 23

As only oestrogen has those specific receptors

Question 24

Describe how translation can epigenetically control gene expression ?

Answer 24

Double stranded RNA broken by enzyme into siRNA
1 of these strands now combines with enzyme
siRNA strand pairs up with complementary bases on mRNA strand.
The enzyme cuts the mRNA into smaller sections

Question 25

How does oestrogen enter the cytoplasm where transcriptional factor is?

Answer 25

Diffuses through the phospholipid bilayer as it is lipid soluble

Question 26

Name a transcriptional factor that initiates transcription

Answer 26

Oestrogen

Question 27

What is transcription of genes controlled by?

Answer 27

Transcription factors

Question 28

What is a suppressor?

Answer 28

Transcription factors that inhibit gene expression

Question 29

Transcription factors move from the ….. to the …..

Answer 29

cytoplasm to the nucleus

Question 30

How do activators work?

Answer 30

Help RNA polymerase bind to the start of a target gene, and activate transcription.

Question 31

How do suppressors work?

Answer 31

Bind to the start of target gene preventing RNA polymerase from binding, stopping transcription.