what are genes

A gene is the basic physical and functional unit of heredity. It is a section of DNA made up of a sequence of As, Cs, Ts, and Gs. Genes carry the information that determines an organisms traits, which are features or characteristics that are passed on from parents to offspring. Every person has two copies of each gene, one inherited from each parent. Most genes are the same in all people, but a small number of genes (less than 1 percent of the total) are slightly different between people. These small differences contribute to each person's unique physical features. Genes can be broken down into two types: the Mendelian gene, which is a basic unit of heredity, and the molecular gene, which is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. Some genes act as instructions to make molecules called proteins, while many genes do not code for proteins. Genes in general direct specific processes in the body by coding for proteins, and a gene's primary function can be broken down into four general categories: encoding proteins to build something in the body, encoding proteins that help direct the body to do something, encoding proteins that help the body respond to its environment, and encoding proteins that help regulate the expression of other genes.