Genetics - What are Genes?

Inside every cell of each living thing (plant or animal) are sets of instructions called genes. The genes provide the instructions on what is the plant or animal, what it looks like, how it is to survive, and how it will interact with its surrounding environment. The genes are strung together in long stands of material called deoxyribonucleic acid (DNA) and these long strands are called chromosomes. Most living things have pairs of chromosomes (one from each parent), though they may have a different number of chromosomes from another living thing. For example, humans have 23 pairs of chromosomes and the fruit fly has 4 pairs.

Each gene is made up of long combinations of four different nucleotide bases. It is the various combinations of the nucleotide bases that determine everything about a living creature.

The four nucleotides are called:

* adenine(A),
* cytosine (C),
* guanine (G), and
* thymine (T).

The gene for green eyes might have this nucleotide sequence.

AAACCGGTTTTT

The gene for blue eyes might have this nucleotide sequence.

AAACCGGTTTAA

Notice how the nucleotide sequences below are very similar. The only difference being the last two bases. They both describe an eye with the last two characters stating the color of the eye.

Note: These gene formula are not accurate, the correct sequence could be up to several thousand bases long).

Many of the genes have a quality known as Dominate or Recessive. Dominant traits are more common than Recessive traits due to this quality.