14.1 – 14.4 By: Sheyanne Wertz and Alexis Reid Period C

14.1: P ROTEINS Proteins are the most important biological compound There are many functions of proteins Structure- structural protein make up animals. Two important structural proteins are collagen and keratin Catalysis- every reaction that takes place in the living organisms are catalyzed by proteins called enzymes.

F UNCTIONS OF P ROTEINS Movement- Every time we move we use muscles. Muscles are made up of protein molecules called myosin and actin. Transport- Hemoglobin is a protein in the blood that transports oxygen from the lungs to cells and co2 from the cells to the lungs. Hormones- Many are proteins. Such as insulin, erythropoietin, and human growth hormones.

M ORE FUNCTIONS Protection- If a foreign protein gets in our body, our body will make our own protein called antibodies to counteract it. The antibody production helps fight diseases. Storage- Proteins store materials Regulation- Proteins control genes, regulating the kind of protein synthesized in a cell, but also dictate when such manufactures take place

14.1 CONTINUED A typical cell has 9,000 different proteins The entire human body has 100,000 proteins Proteins can be classified in two different groups Fibrous protein- Insoluble in water used for structural purposes Globular proteins- More or less soluble in water used for nonstructural purposes.

14.2 Amino acids are organic compounds containing an amino and a carboxylic acid group Proteins are chains of amino acids 20 common amino acids found in proteins They are known as the alpha amino acids

14.2 C ONTINUED They are classified by their side chains Nonpolar - Hydrophobic Polar but neutral - Hydrophilic Acidic - Hydrophilic Basic - Hydrophilic All amino acids in human tissue are L- amino acids They are tetrahedral structures

14.3 Amino acids in the solid state, as well as in water carry both positive and negative charges. They are called zwitterions German word “zwitter” means hybrid They are ionic compounds

14.3 CONTINUED The pH at which the number of positive charges equals the number of negative charges is the isoelectric point of an amino acid or protein. Amino acids are zwitterions High melting points, fairly soluble in water

Zwitterions with different pH levels

14.4 Amino acids are almost identical besides their side chains The side chain is what gives the amino acid its unique nature and its particular properties Some amino acids have charged side chains

Amino acid side chain

14.4 C ONTINUED Cysteine is a special amino acid because its side chain can form disulfide bridges with another cysteine Aromatic amino acids are important physiologically Precursors of neurotransmitters Absorb ultraviolet light Allows us to easily measure and locate them

Disulfide bond found in cystine