1. Proteins
Amino acids structure
Peptide bonds
(condensation reaction)

2. Protein Structures
Primary Structures: peptide bonds between amino acids
Secondary Structures: hydrogen bonds between COOH & NH2 of different AA
Tertiary Structures: disulfide bonds between variable side groups
Quaternary Structures: multiple polypeptides

3. Primary Structure … Try – Gly – Lys – Pro – Val – Arg – Glu …
N-terminal C-terminal

4. Secondary Protein Structure: hydrogen bonds
Alpha-helix
Beta-pleated sheets

5. HEAT
Proteins are wound-up, and held together by disulfide & hydrogen bonds. Denaturation – change of molecular shape (unwind), and hydrogen bonds are broken. Coagulation - liquid  semisolid
HEAT

7. Denaturation
Beating an egg
Cooking an egg

8. Denaturation Thermal denaturation (stable 47-67°C)
Ionic strength/pH (disrupt H-bonds)
Mechanical treatment (beating)
Lab: Effect of Acid on Proteins

9. Effects of Acid on Proteins
How does gastric juice facilitate protein digestion?
Outer-most layer of protein denatures and coagulates first
Key words: H+ ions, hydrogen and disulfide bonds

10. Anatomy of an Egg

11. Some Parts You Can Name…
Albumin (white)
Yolk
Shell: pores

13. Shell
Texture
Pores

14. Inner & Outer Membrane
Protection
Air cell in between
Semi-permeable

15. Air Cell
Location
Formed after being laid

16. Albumen > 50% of an egg ~ 90% water 40 different proteins
Thick & thin albumen

17. Chalazae
opaque twisted cordlike
anchoring the yolk
prominent in fresh eggs

18. Vitelline Membrane
enclosing the yolk

19. Yolk even more protein, less water vitamins (A, B, D)
mineral (Fe, Ca, P)
some fats

20. Denaturation