Biological Computation

Introduction and Biological Background    ◾    21

carries oxygen in the bloodstream to the muscles, has four cavities that

can be loaded with heme, an iron compound that can bind to oxygen.

Researchers distinguish between several levels in the organization of

proteins. e rst, called the primary structure, refers to the sequence of

amino acids. e secondary structure describes local structures along the

amino acid sequence such as dierent kinds of helices, extended strands

that combine to create sheets, turns, and loops. ese structures are

maintained by a network of chemical bonds (hydrogen bonds) between

neighboring amino acids. e three-dimensional structure of a protein is

referred to as its tertiary structure and describes the three-d ...