Mutations

Question 1

Wha is a mutation?

Answer 1

A heritable alteration in a end or chromosome (change in nucleotide sequence in DNA) + the process that produces the alteration

Question 2

Two sources of exogenous mutations

Answer 2

• ionising radiation + free particles
• mutagenic chemicals + anti-cancer agents

Question 3

Two sources of endogenous mutations

Answer 3

DNA replication defects
Transposable elements

Question 4

What are the 3 types of mutagens?
What do they cause?

Answer 4

Spontaneous events
Exogenous
Endogenous

Cause defective or error prone DNA repair

Question 5

Identify 6 things which can lead to formation of free radical

Answer 5

UV ligh
Ionising radiation
Smoking
Air pollution
Inflammation
Metabolism

Question 6

What are transposable element?

Answer 6

DNA sequence which can change to position within a genome

Question 7

What are the 4 micro mutations (DNA)?

Answer 7

Insertion
Deletion
Duplication
Inversion

Question 8

What do missense mutations do?

Answer 8

Change the amino acid coded for

Question 9

What are 5 type of macro mutations (chromosomal)?

Answer 9

Duplication
Inversion
Deletion
Insertion
Translocation

Question 10

What mutations change the polypeptide length?

Answer 10

Frameshift mutations
Mutation of stop codon
Nonsense mutations - stop codon added prematurely

Question 11

What do nonsense mutations do?

Answer 11

Add a stop codon prematurely

Question 12

What is a silent mutation?
Other names

Answer 12

Has no affect
Neutral/synonymous

Question 13

Types of DNA substitutions

Answer 13

Transition- switch base of same type
- purine > purine
- pyrimidine > pyrimidine

Transversion- change to different type of base
- purine > pyrimidine
- different size so bigger impact

Question 14

What is a chromosome deletion mutation?

Answer 14

Removal of a section of chromone

Question 15

What is a chromosome duplication mutation?

Answer 15

Section copied and inserted

Question 16

What is a chromosome inversion mutation?

Answer 16

One second turned over - opposite order

Question 17

What is a chromosome insertion mutation?

Answer 17

One part from a chromosome is removed and added to another

Question 18

What is a chromosome translocation mutation?

Answer 18

Genetic information is switched between two chromosomes

Question 19

What is Cri du Chat syndrome?

Answer 19

Deletion mutation of short arm of chromosome 5

Question 20

What is Robertsonian translocations?

Answer 20

Affects acrocentric chromosomes - 13,14,15,21,22
Chromosomes break at centromere before refusing
Short arms ost
4 long arms fuse

Question 21

What can Robersonian translocations cause?

Answer 21

Down’s syndrome
Patau syndrome

Question 22

What is polyploidy?
Most common cause

Answer 22

Gaining a whole set of haploid chromosomes
Most common cause- polyspermy

Question 23

What is polyspermy?

Answer 23

More than one sprem fertilises egg

Question 24

What is aneyploidy?
Cause

Answer 24

Loss or gain of a single chromosome
Cause - non-disjunction in meiosis

Question 25

What is Patau syndrome?

Answer 25

**Trisomy of chromosome 13** - Robersonian translocation Changes to shape of face Cleft palate Polydactylyl Deformed feet

Question 26

What are acrocentric chromosomes?

Answer 26

Centromere is very close to top 2 long arms q 2 short arms p 13,14,15,21,22

Question 27

What is non-disjunction?

Answer 27

Failure of 1 or more pairs of homologous chromosomes to separate normally in nuclear division

Question 28

What is mosaicism? What is it caused by?

Answer 28

The presence of two or more cell lines in an individual Caused by non-disjunction in mitosis

Question 29

How can a silent mutation occur?

Answer 29

Amino acid coding is **degenerate**