1. Proteins are versatile macromolecules that serve as building blocks and catalysts

2. Proteins are bodybuilding macromolecules

3. Proteins are an essential dietary component  Growth  Repair  Replacement How many grams of protein do we need everyday?

4.  Food labels indicate an item’s protein content.  Why is this insufficient for you to determine whether you are protein deficient, even if your protein intake exceeds your recommended daily amount?

5. Not All Proteins are Created Equal  Complete proteins have all essential amino acids  Incomplete proteins  Complementary proteins

7. Which combination of foods would contain all of the essential amino acids? 1.Almonds and white rice 2. Almonds and lentils 3. White rice and lentils 4. Almonds and apples

8. Take-home message  Of the 20 amino acids that serve as building blocks for proteins, about half are essential for humans; they cannot be synthesized by the body, so they must be consumed in the diet.  Complete proteins contain all essential amino acids, while incomplete proteins do not.

9. A protein’s function is influenced by its three-dimensional shape  Peptide bonds

10. Primary Structure  The sequence of amino acids

11. Secondary Structure  Hydrogen bonding between amino acids  The two most common patterns: twist in a corkscrew-like shape zig-zag folding

12. Tertiary Structure  Folding and bending of the secondary structure  Due to bonds such as hydrogen bonds or covalent sulfur- sulfur bonds.

13. Quaternary Structure  When two or more polypeptide chains are held together by bonds between the amino acids on the different chains.  Hemoglobin

14.  Egg whites contain much protein.  Why does beating them change their texture, making them stiff?

15.  Egg whites contain much protein.  Why does beating them change their texture, making them stiff?

16. Why is wet hair easier to style than dry hair?

17. Why do some people have curly hair and others have straight hair?

18. Getting hair straightened at a hair salon involves: 1.changing the tertiary structure of the hair proteins. 2.reforming hydrogen bonds that have been broken. 3.changing the primary structure of the hair proteins. 4.Both 1 and 2.

19. Take-home message  A protein’s particular amino acid sequence determines how it folds into a particular three- dimensional shape.  This shape determines many of the protein's properties, including which molecules it will interact with.  When a protein's shape is deformed, the protein usually loses its ability to function.

20. Enzymes are proteins that initiate and speed up chemical reactions.

23. Activation Energy Chemical reactions occurring in organisms can either release energy or consume energy. In either case, the reaction needs a little “push” in order to initiate the reaction- called activation energy. Enzymes act as catalyst by lowering the activation energy

24. An enzyme can reduce the activation energy in a variety of ways 1) By stressing, bending, or stretching critical chemical bonds 2) By directly participating in the reaction 3) By creating a microhabitat that is conducive to the reaction 4) By simply orienting or holding substrate molecules in place so that they can be modified.

25. How does lactase catalyze breakdown of lactose into glucose and galactose? 1.By stressing and bending the covalent bond between the two sugars. 2.By directly participating in the reaction. 3.By creating a microhabitat conducive for bond breaking. 4.By reorienting the molecule in space.

26. Take-home message  Enzymes are proteins that help initiate and speed up chemical reactions.  They aren’t permanently altered in the process but rather can be used again and again.

27. Enzymes regulate reactions in several ways (but malformed enzymes can cause problems)

28. The rate at which an enzyme catalyzes a reaction is influenced by several chemical and physical factors

32. “Misspelled” Proteins  Incorrect amino acid sequence  Active site disruptions  Phenylketonuria

33. Why does a misspelling in the primary structure of phenylalanine hydroxylase inhibit its function? 1.Enzyme shape is incorrect 2.Enzyme fails to bind substrate 3.pH has changed 4.Presence of an inhibitor 5.Both 1 and 2.

34. Q Why do some adults get sick when they drink milk?

35. Take-home message  Enzyme activity is influenced by physical factors such as temperature and pH, as well as chemical factors, including enzyme and substrate concentrations.

36. Take-home message  Inhibitors and activators are chemicals that bind to enzymes. By blocking the active site or altering the shape or structure of the enzyme, they can change the rate at which the enzyme catalyzes reactions.