Mutations

Question 1

what is a mutation?

Answer 1

it is a permanent change to a gene or chromosome leading to a new characteristic in an organism

Question 2

what are mutagens?

Answer 2

the are agents which are known to increase the rate at which mutations occur.
this can include:
- UV light
- X-rays
- radiation
- chemicals e.g. sulfur dioxide or antibiotics

Question 3

what is a somatic mutation?

Answer 3

it is when a mutation has occurred in a body cell.

once the organism dies the mutation will be lost

Question 4

what is gamete mutation?

Answer 4

known as a germline mutation.

the individual is not affected but the individual produces gametes with the changed DNA.

Question 5

what are the two types of mutations?

Answer 5

gene mutation

chromosomal mutation

Question 6

what is a gene mutation?

Answer 6

occurs when there is a change in a single gene.
they occur during replication of the DNA molecule before cell division. if DNA is copied incorrectly the changed DNA will continue to be copied in all future divisions.

Question 7

three types of gene mutation?

Answer 7

1. a single base is changed in a gene the DNA may now code for a new amino acid and a completely different protein
2. the protein may not be created at all
3. there may be no change

Question 8

types of gene mutations (3)

Answer 8

albinism: is the result of a missing protein melanin, which is responsible for the pigment of hair.skin and eyes

Duchenne muscular dystrophy:
missing the protein dystrophin results in the wasting of the leg muscles and later the arms, shoulders and chest. muscle weakness at the age 3-5 and then eventually death due to the failure of respiratory muscles
boys don’t usually live past the age of 25

cystic fibrosis: results from a change in the DNA of the CFTR gene resulting in different amino acids in the CFTR protein.
CFTR regulates the development of the chloride channels in the cell membrane, without the person cannot transport chloride ions and the movement of water into and out of the cells.
the person suffers from a salty-tasting skin, persistent coughing, wheezing and digestive problems

Question 9

what are chromosomal mutations

Answer 9

occur when there is a change in the whole or part of a chromosome
many genes are affected

Question 10

name and explain the 5 different types of chromosomal mutations

Answer 10

1. deletion- part of a chromosome is lost
2. duplication - a section of a chromosome occurs twice
3. inversion - breaks occur in a chromosome and the broken piece joins back in but inverted (flipped)
4. translocation - part of a chromosome breaks off and is re-joined to the wrong chromosome
5. non-disjunction - during meiosis a chromosome pair does not separate and so one daughter cell has one less chromosome (monosomy) and one has one extra (trisomy)

Question 11

what is monosomy?

name and describe two types of syndromes that monosomy causes

Answer 11

when there is a missing chromosome

1. cri-du-chat where part of chromosme 5 is missing. infants often have problems with their larynx and nervous system.
2. turners syndrome - due to a missing sex chromosome. they are born female but are short in statue, lack secondary sex characteristics and are infertile

Question 12

what is trisomy?

name and describe the tow types of syndromes that trisomy causes

Answer 12

is when a person has an extra chromosome

1. down syndrome - occurs when an individual has an extra chromosome on pair 21
2. pataus syndrome occurs when an individual has an extra chromosome 13. they usually have smaller heads, mental retardation, extra fingers, cleft palate and malformations of the eyes and ears

Question 13

what is polyploidy?

Answer 13

an organism which has an extra set of chromosomes e.g. down syndrome