These proteins, which include enzymes that do specialized jobs, control the activities of the cell.
Different cells have different activities.
By controlling protein synthesis within each cell, the genes that make up DNA control the life of the entire organism. Although the outcome of protein synthesis can be involved and quite complex, its purpose is rather straightforward. In a hair follicle cell, a protein called keratin is made. Lots of it. Many ribosomes can be working on a single strand of mRNA at once.