The document discusses the key elements of genetic variation, including alleles, gametes, and mutations. Alleles are different versions of the DNA code within cells. Gametes are male and female sex cells that contain 23 chromosomes each. Genetic variation is caused by gamete formation which creates random sex cells, fertilization where male and female gametes combine randomly, and mutations from incorrect DNA division or environmental factors damaging cells.

1. The next slide shows the key elements for
this topic in the Gateway Biology for OCR
Biology

2. Alleles
Genetic variation
are
are
Different versions of the
cells DNA code
Gametes
Caused by
Male and female sex cells
Contain only 23 chromosomes
and all are different
1. Gamete formation –
splitting of the male and
female cell in gamete
formation leads to random
different sex cells.
2. Fertilisation – when
gametes combine during
fertilisation the 23
chromosomes from the
male and female randomly
form the 46 chromosomes
of the new baby
3.Mutations –
spontaneous incorrect
division of DNA OR
environmental factors such
as aggressive chemical
attack, UV, X rays or
gamma rays on cells