14.1 – 14.4

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

2. 14.1: Proteins • 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.

3. Functions of Proteins • 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.

4. More 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

5. 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.

6. 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

7. 14.2 Continued • 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

9. 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

10. 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

11. Zwitterions with different pH levels

12. 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

13. Amino acid side chain

14. 14.4 Continued • 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

15. Disulfide bond found in cystine