8.1.1 - Origins of genetic variation

Question 1

What is the name given to factors that cause mutations?

Answer 1

Mutagens

Question 2

What are 3 examples of gene mutations?

Answer 2

substitution
Deletion
Insertion

Question 3

What is a mutation?

Answer 3

A mutation is a change in the DNA base sequence which results in a new and different allele.

Question 4

What happens in crossing over?

Answer 4

Homologous chromosomes line up.
They twist around each other and join at the chiasmata.
Parts of sister chromatids break off and swap over so genes are exchanged.

Question 5

Describe how a translocation occurs.

Answer 5

Part of a chromosome breaks off.
This joins to another chromosome which is non-homologous.

Question 6

What is a non-disjunction mutation?

Answer 6

During meiosis, the homologous pair may fail to separate, as a result a gamete may have 2 copies of that chromosome or none.