1. Section 6.4 Proteins

2. Objectives
Distinguish among proteins, carbohydrates, lipids and nucleic acids. (SPI )
List the functions of proteins.
Describe the structure of amino acids and proteins.
Describe factors that influence protein shape.
Identify positive tests for carbohydrates, lipids and proteins (SPI )

3. Proteins Functions Monomers Polymers Form cell structures
Chemical messengers Enzymes
Body defense
Regulation
Movement & support
Monomers
amino acids
Polymers
Polypeptides
Proteins

4. Protein “Prime importance” Found in: Cells (2/3 of dry cell weight )
Tissues
All body fluids except urine and bile
Not stored for future use (like
carbohydrates and lipids)

5. Proteins  Major components of:
Skin, nails, claws, hair, wool, feathers, hooves, muscles, tendons and cartilage.

6. Proteins  Essential Chemicals  Support (keratin/collagen)
 Enzymes (specific catalysts)
 Transport (channel proteins/hemoglobin)
 Defense (antibodies)
 Hormones (regulatory - insulin)
 Motion (actin/myosin)

7. 20 amino acids in proteins
Protein Composition
Polymers
Amino Acid Monomers
20 amino acids in proteins

8. Amino Acids
R C H C
NH2 O OH
acid group
amino group

9. Two or more amino acids bonded together.
Peptide
Two or more amino acids bonded together. AA X

10. Peptide Bond
Covalent bond forms between amino acids during dehydration synthesis reaction.

11. Polypeptides Chains of many amino acids joined by peptide bonds.
Proteins may contain more than one polypeptide chain.

12. Shape determines function.
Protein Structure
Shape determines function.

13. Levels of Protein Structure Primary
The sequence of amino acids.

14. Levels of Protein Structure Secondary
 Helix

15. Levels of Protein Structure Secondary
 Pleated Sheet

16. Levels of Protein Structure Tertiary
Secondary structures are folded.

17. Levels of Protein Structure Quarternary
Results when two or more polypeptides combine. (Hemoglobin, most enzymes)

18. Denaturation Of Proteins
Loss of normal shape – a physical change.
Once a protein loses it normal shape, it cannot perform its usual function.

19. How Proteins Can Be Denatured
Temperature
Cooking an egg
Albumin congeals
Addition of hydrogen or hydroxide ions (large pH changes)
Adding acid to milk
Causes curdling
Vigorous Shaking – making whipped cream
Organic Solvents
Salts of heavy metals (mercury, silver & lead)
Detergents
Ultraviolet Radiation

20. Pink – peptides (short chains)
Test for Proteins
Reagent - Biuret
Positive
Violet proteins
Pink – peptides (short chains)

21. Enzymes Extremely Important Type of Proteins

22. What role do enzymes play in organisms?
Essential Questions
What is an enzyme?
What role do enzymes play in organisms?

23. Objectives
Identify how enzymes control chemical reactions in the body (SPI )
Explain how enzymes affect activation energy.
Describe how an enzyme’s shape is important to its function.

24. Key Terms
Activation energy
Catalyst
Substrate
Active site

25. Reactions in Cells are Orderly

26. What must happen for a chemical reaction to begin?

27. Chemical bonds must weaken!

28. What will weaken chemical bonds!

29. Input energy!

30. What is this energy called?

31. Activation Energy

32. What form of energy is most readily available?

33. Heat

34. Why is heat a poor choice for cells?

35. Can lead to cell death.

36. What works better?

37. Use a catalyst.

38. In biological systems, what are these catalysts called?

39. Enzymes

40. How do they work?

41. They lower activation energy!

42. Energy of Activation

43. Activation Energy

44. Enzyme-Substrate Complexes

45. Important Enzyme Terms

46. Enzyme-Substrate Complexes

47. Degradation Reaction (Hydrolysis for example)

48. Some enzymes change shape.

49. What environmental conditions affect enzyme activity? Why?
Hint: Remember that enzymes are proteins!

50. Factors Affecting Enzyme-Catalyzed Reaction Rates
Substrate Concentration
Enzyme Concentration
Temperature (optimum)
pH (optimum)

51. Temperature and Enzyme-Catalyzed Reaction Rates

52. pH and Enzyme-Catalyzed Reaction Rates

53. Review How do enzymes affect activation energy?
Describe how an enzyme’s shape is important to its function.

54. Review List the functions of proteins.
Describe the structure of amino acids and proteins.
Describe factors that influence protein shape.