PROTEINS

Protein Molecules Are very large and complex ( often called macromolecules) Made up of hydrogen, carbon, oxygen, nitrogen, and sometimes other elements. Contains nitrogen which is not found carbohydrates or lipids. Made of chain of amino acids.

Amino Acids A type of organic acid ( molecules that contain a carboxyl group) Contains amine group – has two atoms of hydrogen and one atom of nitrogen.

Peptide Bonds Amino acids link to form protein molecules through peptide bonds. Some protein chains contain only a few amino acids but most molecules have 100 to 500 amino acids and some thousands. Peptide bonds hold chains of amino acids together in folds and tangles (like a wad of string) rather than a railroad track.

Shape and Function A protein’s shape determines its function. Rope-like fibers are fibrous proteins often serve as connective tissue such as collagen and elastin. Compact protein molecules that fold and bond similar to a ball called a globular shape make them good carriers. Hemoglobin is an example and carries oxygen in the blood.

Denaturation of Protein Denaturation is a process that changes the shape of a protein molecule without breaking its peptide bonds. Denaturation breaks the hydrogen bonds that create the twists and turns of a protein molecule. Coagulation changes a liquid into a soft, semisolid clot or mass.

Denaturation of Protein

Coagulation occurs when polypeptides unfold during denaturation. An example of coagulation is scrambling of egg. The protein coagulates as the egg cooks.

Many Functions of Proteins To build new body cells for growth. To repair or replace cells To make up enzymes and hormones used in many body processes. Pick up, deliver, and store nutrients in cells =example is lipoproteins carry lipids.

Proteins called antibodies help fight disease. – They form antibodies which are large proteins that weaken or destroy foreign substances in the body. They stabilize PH levels – they attract or release hydrogen ions in order to control acidity. They can supply energy if needed

ESSENTIAL AMINO ACIDS Amino acids the body needs but can not make itself. We must get them from eating them.

Complete - Incomplete A complete protein has all of the essential amino acids. An incomplete protein is missing one or more of the essential amino acids. A high quality protein contains all of the essential amino acids in proportion to the body’s need. An Egg is the standard.

Proteins have 4 calories per gram. Foods high in protein are all animal (meat, fish, poultry) or foods from animals such as dairy and eggs. Legumes (dry beans) and grains complement each other and combined supply all the essential amino acids. Examples rice and beans Macaroni and cheese is another complementary combination.