There is a nucleus in cells. This controls what the cell does. Inside the nucleus is chromosomes. Chromosomes are made up of DNA strands. DNA is made up of our genes!
Genes are what give us our eye colour and are what make us inherite disorders etc. The parents pass these on to their child in sex cells. If you get different versions of these it is called alleles.
The human body contains 23 pairs of chromosomes.
A pair of chromosomes carry the same gene but different versions of it. So the pair may be the same for example two brown eyes, or it maybe different for example brown and blue.sex cells only get 1 chromosome from each pair.so when you have the pairs one comes from the mum and one from the dad. This is the reason why the child looks simaler to a parent but never identacal.
A female has two X chromosomes. A male has a Y and a X chromosome. When sex cells form the pair of sex chromosomes are separated. This means that all normal egg cells always has an X. Where as half the sperm cells have an X and the other half have Y. For this reason it should be around equal of boys and girls in the population.
Did you know that once evreyone was female. Even the males were once female. Basicly whaat happens is the Y chromosome, also known as 'sex determing region Y' produces androgens. This causes the testes to grow.