Amino Acids

Amino acids are the building blocks of proteins. Amino acids bind together to form polypeptide chains, and these polypeptides fold and coil together into specific conformations to form proteins. There are 20 different amino acids, each amino acid consisting of four distinct partners. The first is a carboxyl group. A carboxyl group has very weak acids that are able to donate hydrogen ions to biological reactions. The second partner is the amino acid group. Amino acid groups act as the base which, along with pH, the electronegativity of the entire amino acid is dependent

on. The third component of amino acids is the hydrogen atom. Finally the last component of amino acids is the variable R group. The R group is the component that determines many of the cells unique characteristics such as its hydrophobic or hydrophilic properties. The R group can be anything from a hydrogen atom to a carbon skeleton with many functional groups attached. These four components of amino acids are all attached to a central carbon called an alpha carbon.

Through a process called dehydration reaction, amino acids are able to bond to each other to form polypeptides. For dehydration reaction to occur, the carboxyl group of one amino acid must be adjacent to the amino group of another. When they are adjacent to one another, an enzyme can cause them to join by catalyzing dehydration reaction. This same process repeated over and over again will yield a polypeptide, the polymers of proteins. The polypeptides then foil and coil to form proteins.

Proteins have four distinct levels of structure. The first is the primary structure. The primary structure is the most basic of all the structures. It is the proteins unique sequence of amino acids. Any slight change in the structure of the primary structure of a protein can affect its ability to function. For example, the substitution of one amino acid for another can alter the protein and make it unable to function. This property is the cause of sickle cell anemia. The primary structure of hemoglobin is affected by the replacement of one amino acid for another.

The secondary structure of a protein refers to a certain repetition of structures found in proteins. There are two types of secondary structure: alpha-helix and beta-pleated. The alpha-helix structure of a protein is a tight helix formed form a polypeptide chain and it is the result of hydrogen bonds at regular intervals along the polypeptide chain. The delicate coil of alpha helixes is held together by hydrogen bonds