Meiosis and Genetic Variation

DNA from One Generation is Passed to the next by Gametes

• Gametes are the sperm cells in males and egg cells in females. They join together at fertilisation to form a zygote, which divides and develops into a new organism.
• Normal body cells have the diploid number (2n) of chromosomes - meaning each cell contains two of each chromosomes, one from the mum and one from the dad.
• Gametes have a haploid (n) number of chromosomes - there's only one copy of each chromosome.
• At fertilisation, a haploid fuses with a haploid egg, making a cell with the normal diploid number of chromosomes. Half these chromosomes are from the father (the sperm) and half are from the mother (the egg).

Gametes are formed by Meiosis

Meiosis is a type of cell division. Cells that divide by meiosis are diploid to start with, but the cells that are formed from meiosis are haploid - the chromosomes number halves. Without meiosis, you'd get double the number…