Genes and how they work

The organs and tissues of the body are made up of tiny building blocks called cells. Every cell contains all the biological information we inherit from our parents. This information is stored in our genes in the centre (nucleus) of every cell.

Genes affect the way we look and how our bodies grow and work. Different genes have different functions. Some things about our appearance such as our eye colour are completely determined by our genes. But most things about us are the result of an interaction between our genes and our environment. For example, our height and weight are linked to the genes we inherit (someone with tall parents is likely to be tall) but also to our diet, exercise, any childhood illnesses and so on.

Genes are grouped together on chromosomes. Every cell has 46 chromosomes, arranged into 23 pairs. One chromosome in every pair comes from your mother and one comes from your father, so half of your genes come from your mother and half from your father.

The information inside our genes is written in a ’code’ made up of four chemicals (bases): adenine, thymine, cytosine and guanine (shortened to the letters A, T, C and G). These four chemicals, repeated in different combinations, contain all the information our body needs to function. This coded information is called DNA (deoxyribonucleic acid).

DNA labelled
DNA labelled

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Cancer and genes

Faults (mutations) in some genes can cause cells to grow in an uncontrolled way, forming tumours.