Almost all of your cells contain a complete copy of your genetic information – your genome – across 46 chromosomes (23 pairs).
Sperm and egg cells (known as gametes) are different – they have a total of 23 chromosomes, only one of each pair. When a sperm and egg combine during fertilisation, they form a single cell (zygote) that contains the full set of 46 chromosomes, 23 from each parent.
This single cell divides many times during a person's growth and development, with each new cell containing a complete copy of the genome.
