Genes and chromosomes explain the uniqueness of individuals as well as why features, traits and diseases occur in some families.
Every living thing has a set of “blueprints”. These blueprints are called genetic code and they determine what that living thing will be – a flower, tree, insect, animal or human.
The genetic code is made up of genes. These genes are put together in a special order to form DNA. DNA is grouped into units called chromosomes.
Humans have 23 pairs of chromosomes, making a total of 46. We receive half of our chromosomes from our mother and half from our father.
The X and Y chromosomes are known as sex chromosomes. Females have two X chromosomes and males have one X and one Y chromosome.
The 23 pairs of chromosomes can be identified by a high powered microscope according to their size, shape and the way they pick up laboratory dyes.
These chromosomes are in every cell of your body.
When a cell divides, the genetic information is copied so that each new cell will have the same code. Cells can sometimes change the information contained in their genes which can cause illnesses, such as some types of cancer.
If the mutation exists in egg or sperm cells, children can inherit the mutation from their parents.
Sometimes when an egg and sperm unite, the cell can get too many or too few chromosomes. An example of this is Down Syndrome – a condition where individuals have an extra 21st chromosome.