🍭 Causes of variation (CCEA)

Let’s look at 3 broad categories of source of genetic variation: gene mutation, chromosome mutation and sexual reproduction.



DNA mutation occurs spontaneously and creates a direct change in the genetic material. Single bases may be changed, added or removed, or even large chunks of chromosomes can be swapped between them or duplicated. Whole chromosomes, too, can shift around.


Mutations are a random occurrence during DNA replication and the rate of mutation is influenced by external factors such as UV radiation. There are different types of mutation…