Date post: | 16-Jan-2015 |
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The next slide shows the key elements for this topic in the
Gateway Biology for OCR Biology
Genetic variation
Caused by
Alleles
are
Different versions of the cells DNA code
Gametes
are
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