1. Genes
Genes play an important role in our physical appearance.
They carry information that makes you who you are: curly hair, blue eyes, thin or at risk for heart diseases – which you may inherit from your parent (s).
What is a gene?
Each cell in the human body contains about 25,000 genes which carry the information that determines your traits.
Where are genes?
They are on chromosomes and the chromosomes are inside cells.
Your body is composed of billions of cells.
The chromosomes and genes are made of DNA.

2. Most cells have one nucleus and it acts like the brain of the cell telling every part of the cell what to do.
A cell nucleus contains 46 individual chromosomes or 23 pairs of chromosomes.
Half of the chromosomes come from one parent and half from the other parent.
The sex chromosomes determine your sex: X and Y
Females have two X chromosomes and Males have one X and one Y
How do Genes Work?
Each gene has a special job to do.
The DNA in a gene spells out specific instructions for making protein.
Proteins are the building blocks for everything in your body; bones, teeth, muscles and blood are all made up of proteins.
The proteins help our bodies work, grow and stay healthy.
We think that each gene may make as many as 10 different proteins.

3. Some genes don’t work right and this creates specific illnesses.
Genes that may have been changed are called mutations.
Mutations may be partly blamed for lung problems, cancer and other illnesses.
It may be due to missing genes or extra parts of genes or chromosomes.
Some of these illnesses may be inherited from parents.
What is gene therapy?
It uses genetic engineering to treat a disease caused by a gene that has changed in some way.
We can replace a sick gene with a healthy one.