Genomics is a field of biology that deals with the structure, function, evolution, mapping, and editing of genomes. A genome refers to the complete set of DNA of an organism, including all of its genes. It differs from genetics, which refers to the study of individual genes and their roles in inheritance. Genomics focuses on the combined characterization and quantification of all genes of an organism, their interrelations and influence on the organism. Genes express the production of proteins with the assistance of enzymes and messenger molecules. The proteins make up body structures such as organs and tissues as well as control chemical reactions and carry signals between cells.