DNA 101

In this image, cellular machinery (in yellow) is transcribing DNA (the chain on the right) into RNA (upper left). Illustration by Linda Nye

DNA is short for deoxyribonucleic acid. Two chains of four chemical bases (abbreviated A, T, C and G) make up DNA and act as a cell’s recipe book to make proteins. The particular sequence of a DNA chain – meaning the precise order of the four chemical bases – determines what will be made. A DNA segment beginning with ATTCGC would produce a very different protein than one that starts with CCGTAT. This can be likened to adjusting the order of letters in a word. Though the letters are the same, the meaning changes. For example,  act means something very different than cat.
Not all DNA is destined to become a protein. Just as a recipe might contain more information than just a list of ingredients, only some regions of your DNA – called  – are directly translated into proteins. Cellular machinery follows the instructions written in a gene’s recipe to create a corresponding sequence of   which is chemically similar to DNA but acts as a messenger, carrying the recipe from the . Out in the cell’s the mRNA sequence is read by more machines, called Following the mRNA instructions, ribosomes string together  the building blocks that make up proteins. Proteins do most of the work in the cell.
As  producing two cells where there was once only one, the parent cell’s DNA is duplicated and the same protein-making recipe is passed on to the daughter cell.