Genetic Information

In the nucleus of every cell there are chromosomes.

Chromosomes are long threads made of DNA.

DNA = carries a code that instructs the cell about

Gene = carry instructions (genetic information).

Genes come in different forms for example eye colour: green, blue, brown.

3.13 Recall that the nucleus of a cell contains chromosomes on which genes are located.

Fertilisation

Sex cells (egg and sperm) are called gametes.

The nuclei of the gametes only contain half the chromosomes of normal cells.

So during fertilisation one sperm cell enters and ovum (egg cell) and the two nuclei fuse to form a nulceus with a complete set of genes.

Fertilisation

Keywords

Nucleus Chromosomes DNA Gametes Fertilisation Cell division Inherited characteristics Embryo mutations

A THE SAME AND DIFFERENT

• what makes us different• what genes are and what genes do.

The Same & DifferentNew plants and animals look a lot like their parents. They have inherited information from them. This information controls how the new organisms develop. A lot of information goes into making a human being. So inheritance does a big job pretty well. All people have most features in common. Children look a lot like their parents. If you look at the people around you, the differences between us are very, very small but were interested in them because they make us unique.

The Same & DifferentThese sisters have some features in common.

“Aly & AJ”

Environment makes a difference

Almost all of your features are affected by the information you inherited from your parents. For example your eye colour depends on this information.But most of your features are also affected by the environment. For example, your skin colour depends on inherited information. But if you spend time in the sun your skin will get darker.

Questions1. Choose two students

in the photograph. Write down five ways in which they look different.

2. What two things can affect how you develop?

3. Explain what is meant by inherited information.