Page 51 - Science Coursebook

3.4 More about inheritance

Passing on genes chromosome
As you grow, your cells divide to make more and
more cells. Each time a cell divides, a complete
set of chromosomes and genes is passed on to genes
each daughter (new) cell.

But where did your very first cell come from?
You began your life as a zygote. This is a
cell that was made when the nucleus of your
father's sperm cell and your mother's egg
cell fused together. The sperm cell contained
chromosomes and genes from your father. The
egg cell contained chromosomes and genes from
your mother. Exactly half of your chromosomes
and genes came from each of your parents.

When a cell divides, the daughter cells inherit
exactly the same genes as the parent cell.

At fertilisation, the chromosomes of
the male parent combine with the
chromosomes of the female parent.

So your genes are a mixture of ones that came
from your father, and ones that came from
your mother. They can mix up in almost any
combination. You might have a gene from your
father that gave you curly hair, and a gene from
your mother that helped to make you good Children inherit half of their genes from each of
at running. their parents.

Summary
• Genes are found on chromosomes, in the nucleus of a cell.
• Most genes come in several different forms.
• Offspring inherit half of their genes from each of their parents.

3 Variation and inheritance 49