Proteins serve many purposes in the body such as forming structures, providing support, defense, transporting substances, and speeding up reactions. A protein is made up of polymers called amino acids, of which there are 20 types that differ in their side groups. Amino acids are linked together through dehydration reactions to form polypeptide chains or proteins. There are a huge number of possible protein combinations due to the variety of amino acid arrangements, demonstrating life's unity and diversity. For a protein to function properly it must fold into an exact three-dimensional shape, as the protein's structure determines its role.

1. Start-Up: Which one is a carbohydrate? Which is a lipid? How can you tell?

2. Proteins serve many purposes: Purpose Example 1. Form structures keratin (hair, nails)‏ 2. Provide support control cell shape 3. Provide defense white-blood cells 4. Receive & send messages insulin 5. Transport substances hemoglobin 6. Speed up reactions enzymes

3. But what exactly is a Protein? A protein is a polymer made up of monomers called amino acids There are 20 different amino acids They all have this basic structure, but differ in the side group (R)‏

4. The 9 Hydrophilic Amino Acids (only R groups are shown)‏

5. The 11 Hydrophobic Amino Acids (only R groups are shown)‏

6. A chain of amino acids is called a polypeptide

7. Amino acids are linked together by a dehydration reaction

8. Proteins differ by the arrangement of the 20 possible amino acids If you have a small polypeptide with only 4 0f the 20 possible amino acids you could make: 20 x 20 x 20 x 20 = 160,000 possible proteins!!! This is one example of the unity and diversity of life

9. For a protein to work properly it must be folded or twisted into an exact shape The shape of the protein determines its function (or job)‏ It is very important for a protein to maintain its shape in order to correctly perform its job

10. Structure determines function!