Genes  are  part  or  regions of an organism’s DNA.  DNA  is a blueprint for the bodies´ physical structure and physiological function. Every organism (plant or animal) is made up of cells and every cell has a nucleus.  Within the nucleus are chromosomes each of which contains a chain (or string) of DNA. The genes within DNA are the blueprint which carry information for the production of proteins. Proteins are the building blocks of the structure of the body and in the form of enzymes carry all of life´s biochemical processes (e.g. digestion and repair). It is now known that human beings have between 30-40 thousand genes from which are produced approximately 200 thousand proteins at different stages of life. DNA determines which proteins are produced at a given time and place within the body, which in turn determines the unique structure and function of a given organ (e.g. liver, muscle, brain).

Genes are located in the DNA chains. Regions within the DNA chain, which carry the information for a given protein, are called genes. From the proteins that DNA produces, it builds the body’s structure and controls it’s myriads of specific functions. (For example, one gene might determine eye colour while another gene might contribute to a personality trait). Genes are arranged along the DNA in groups or ‘families’. How each gene behaves is determined not only by how it interacts with other genes in its family, but with other gene families along the DNA chains.  Furthermore, the behaviour of all genes and gene families is influenced by proteins and other chemicals within the organism’s cells and the wider ecological environment it is a part of.

Gene behaviour is highly complex. Genes do not operate in isolation nor do they have a single function.  For example, while all the genes which govern an organism are present in every cell of that organism, they do not function the whole time or in every cell. All genes are associated with a sophisticated set of genetic control elements (i.e. a promoter, enhancers, etc), which allow them to be ‘switched on’ or ‘switched off’ as needed (For example, the genes for flower opening would only operate in the flower bud in spring). The complexity of gene behaviour can be illustrated by comparing the number and type of genes in different organisms - humans share 99% of their genes with sheep, half of their genes with the banana and have 20,000 fewer genes than the maize plant. These comparisons demonstrate that an organism’s structure and life processes are determined not just by how many genes it has but also by what kind of genes it possesses and how its genes interact with each other and the environment both within and outside the organism´s cells.