DNA contains hereditary material. It is located in the nucleus of a cell and contains instructions for producing proteins necessary for cellular function. These instructions are coded using four nitrogenous bases. The sequence of the bases determines the type of protein produced.
The four nitrogenous bases in DNA are adenine, thymine, guanine and cytosine. Each base is attached to a sugar and a phosphate molecule and make up a structure known as a nucleotide. The sugar of one nucleotide attaches to the phosphate of another nucleotide to form a long chain. The nitrogenous bases from two nucleotides bond and result in a ladder-like appearance for the DNA.
DNA is tightly wound into a structure known as a double helix. The double helix unwinds before a cell divides, and the bond between the nitrogenous bases is broken. Each nitrogenous base pairs with a new complementary base to form two copies of the DNA. This ensures that each cell has a copy of DNA.
The process of creating a protein begins in the cell's nucleus. The sequence of nitrogenous bases on a DNA strand is transcribed onto a strand of messenger RNA. The information on the messenger RNA is translated into a sequence of amino acids that link together in a particular pattern to form different proteins.