1. Daily Starter  Explain how a peptide bond is formed. (What is the reaction called and how does it happen?)

2.  TAKE OUT YOUR AMINO ACID CHART

3. Protein Structure The structure of a protein is very complex, with many twists and folds. Proteins are folded into a 3-dimensional structure and held together by chemical bonds.

4. 4 Levels of Protein Structure  Primary  Secondary  Tertiary  Quaternary

5. Primary Structure (1 st Level) The linkage of amino acids in a specific order. This connection is made by dehydration condensation and called a peptide bond.

7. Disulfide Bridges Some primary structures include disulfide bridges These are formed when 2 cysteine amino acid molecules lost their H (hydrogen) and covalently bond together

8. DiSulfide Bridge (Primary structure)

9. Secondary Structure (2 nd Level) The polypeptide chain (chain of a.a.) will begin to form H-bonds with adjacent a.a. molecules H-bonds are somewhat weak so they will form, break, and reform as the protein continues to twist and take a shape.

10. Secondary Structure (2 nd Level) Many H-bonds are needed to hold together a secondary structure (the more, the stronger the hold) There are 2 kinds of secondary folding patterns: 1.Alpha Helix 2.Beta pleated sheets

12. Alpha Helix The slightly negative Oxygen from the carboxyl (COO-) forms a H-bond with the slightly positive Hydrogen from the amino group (NH3+)

13. Beta Pleated Sheet The slightly negative Oxygen from the carboxyl (COO-) forms a H-bond with the slightly positive Hydrogen from the amino group (NH3+)

14. Video on Protein Folding http://youtu.be/lijQ3a8yUYQ http://youtu.be/yZ2aY5lxEGE