by Diego Avilés and Miguel Ibarra

This web is designed to help you understand the process a cell uses to create the different types of proteins necessary for life. The first step in this process is transcription. Then, the cell uses a process called translation, which actually builds amino acid chains and proteins.

Before we delve into the processes that help create proteins, we first have to look at DNA.

DNA

DNA is composed of long chains of nitrogenous bases. Adenine, Thymine, Guanine, and Cytosine are the four types of bases in the DNA double helix. Thymine on one strand will bond with Adenine on the other strand; similarly, Guanine will bond with Cytosine. These nitrogenous bases are connected to sugars (deoxyribose) and phosphates to form the complete double helix structure of DNA (see below). An enzyme called RNA polymerase splits the bonds between two complimentary bases, which will  provide a template for the formation of the mRNA.

A pictorial representation of the structure and bonds in a DNA molecule.

Another representation of a DNA molecule.

A picture of the enzyme RNA polymerase.