what is genes

A gene is the basic physical and functional unit of heredity. It is a section of DNA that contains the instructions for a specific molecule, usually a protein. Genes carry the information that determines an organisms traits, which are features or characteristics that are passed on from parents to offspring. Each cell in the human body contains about 20,000 to 25,000 genes. Some genes act as instructions to make molecules called proteins, while others do not code for proteins. During gene expression, the DNA is first copied into RNA, which can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic traits. Humans have two copies of each gene, one inherited from each parent. Most genes are the same in all people, but a small number of genes are slightly different between people, which contribute to each person's unique physical features. Scientists keep track of genes by giving them unique names.