Each protein is a molecule made up of different combinations of 20 types of smaller, simpler amino acids. Protein molecules are long chains of amino acids that are folded into a three-dimensional ...

How can just four nitrogenous bases--adenine, cytosine, guanine, and uracil--possibly code for all 20 amino acids? Thus, early researchers quickly determined that the smallest combination of As ...

View Full Profile. Learn about our Editorial Policies. Living organisms synthesize a staggering variety of proteins by combining 20 amino acids into chains of any length and order. In the past, to ...