We have mentioned before that the biological macromolecules are all polymers. Carbohydrates are sugar polymers. We built lipids from fatty acids, phosphate groups, and glycerol. Now we come to proteins, which are also polymeric. The subunits which make-up Proteins are Amino Acids. The amino acids are joined together by dehydration synthesis to form chains, which are hundreds of amino acids long; called proteins. Proteins function as enzymes or as structural units in cells. They do most of the "work" in a cell. Almost all of the exciting stuff; metabolism, memory, hormone action, and movement involves proteins.

Amino acids are aptly named. See which functional groups you recognize as part of this amino acid. You will also notice there is an R as part of this molecule. There is no element with the abbreviation, R. This letter is used as a sort of chemical variable, like X in math. At this position (the R-group) in an amino acid, different functional groups can be present. There are twenty different types of amino acids found in proteins. Each has a different R-group.

There are twenty different types of amino acids found in proteins: The eight essential amino acids are shown in bold. Essential amino acids must be acquired in the diet; nonessential amino acids can be synthesized by the body. Complete dietary proteins contain both the essential and nonessential amino acids. Incomplete proteins are missing one or more amino acids. Proteins are digested and degraded by enzymes in the stomach and further digestion occurs in the small intestine. This process takes the proteins you consume and coverts them into the component amino acids by breaking the covalent bonds which connect the subunits of the proteins.

The 20 types of amino acids differ only at the R position.

. See if you can identify the Carboxyl, the Amino, and the R-group of this amino acid (as practice for the exam). [Here is a hint; color the R-Group Blue].

Since each amino acid differs only at the R-group, Their different chemical characteristics arise solely from this part of the molecule. The amino acids within a single protein chain can interact, forming intra-molecular Hydrogen, ionic and covalent bonds. These interactions lead to a twisting and folding of the amino acid chain (protein) that is very important to the function of the protein.

The folding gives each protein a specific shape. The shape (structure) of proteins is extremely important to their function.We will spend a little time in Bio 115 examining the structure of proteins. The interactions between the shapes and charges of proteins is one the most important concepts in Biology.

Since the amino acid R-groups of a protein can interact, their location (order) in the chain is very important to the protein's structure. The amino acids in each type of protein are arranged in a particular order. The order of amino acids is called the protein's primary structure.



A protein's primary structure determines its shape placing the interacting amino acids in a particular position relative to each other.

More Protein stuff.