Question: what is a protein?

Allan Pang answered on 28 Jun 2012:

Proteins are the molecules in our body that essentially do almost all the job in a body of a living organism. Proteins allow to break down food to use it as energy, they also send signals throughout your body, transport nutrients through your body, allow movement, etc. There are several different types of protein, and how they are arranged or structured usually predicts or controls their functions. What is common among all proteins is that they are consisted of amino acids. Amino acids are small molecules made up of atoms of Carbon, Oxygen, Nitrogen, Sulfur and Hydrogen. To make a protein, these amino acids are joined together.

Hope that helps!