The Primary Structure of Proteins
1. What is the primary structure of a protein?
2. Explain the relationship between the primary structure of a protein and the gene for that protein.
3. What type of bond joins the amino acids to one another in the primary structure of a protein?
The Secondary Structure of Proteins
4. Define the secondary structure of a protein.
5. What are the two most common types of secondary structure?
6. What type of secondary structure is characteristic of:
a. the -keratins?
b. silk fibroin?
7. Describe the forces that maintain the two types of secondary structure: -helix and -pleated sheet.
8. Define fibrous proteins.
9. What is the relationship between the structure of fibrous proteins and their functions?
10. Describe a parallel -pleated sheet.
11. Compare a parallel -pleated sheet to an antiparallel -pleated sheet.
The Tertiary Structure of Proteins
12. Define the tertiary structure of a protein.
13. Use examples of specific amino acids to show the variety of weak interactions that maintain tertiary protein
structure.
14. Write the structure of the amino acid produced by the oxidation of cysteine.
15. What is the role of cysteine in maintaining protein structure?
16. Explain the relationship between secondary and tertiary protein structures.
The Quaternary Structure of Proteins
17. Describe the quaternary structure of proteins.
18. What weak interactions are responsible for maintaining quaternary protein structure?
19. What is a conjugated protein?
20. What is a prosthetic group?
An Overview of Protein Structure and Function
21. Why is hydrogen bonding so important to protein structure?
22. Explain why -keratins that have many disulfide bonds between adjacent polypeptide chains are much less elastic
and much harder than those without disulfide bonds.
23. How does the structure of the peptide bond make the structure of proteins relatively rigid?
24. Explain why genetic mutations that result in the replacement of one amino acid with another can lead to the
formation of a protein that cannot carry out its biological function.
Myoglobin and Hemoglobin
25. What is the function of hemoglobin?
26. What is the function of myoglobin?
27. Describe the structure of hemoglobin.
28. Describe the structure of myoglobin.
29. What is the function of heme in hemoglobin and myoglobin?
30. Write the equation representing the binding and release of oxygen from hemoglobin.
31. Carbon monoxide binds tightly to the heme groups of hemoglobin and myoglobin. How does this affinity reflect
the toxicity of carbon monoxide?
32. The blood of the horseshoe crab is blue because of the presence of a protein called hemocyanin. What is the
function of hemocyanin?
33. Why does replacement of glutamic acid with valine alter hemoglobin and ultimately result in sickle cell anemia?
34. How do sickled red blood cells hinder circulation?
35. What is the difference between sickle cell disease and sickle cell trait?
36. How is it possible for sickle cell trait to confer a survival benefit on the person who possesses it?
Denaturation of Proteins
37. Define the term denaturation.
38. What is the difference between denaturation and coagulation?
39. Why is heat an effective means of sterilization?
40. As you increase the temperature of an enzyme-catalyzed reaction, the rate of the reaction initially increases. It
then reaches a maximum rate and finally dramatically declines. Keeping in mind that many enzymes are proteins,
how do you explain these changes in reaction rate?
41. Why is it important that blood have several buffering mechanisms to avoid radical pH changes?
42. Define the term isoelectric.
43. Why do proteins become polycation at extremely low pH?
44. Why do proteins become polyanions at very high pH?
45. Yogurt is produced from milk by the action of dairy bacteria. These bacteria produce lactic acid as a by-product of
their metabolism. The pH decrease causes the milk protein to coagulate. Why are food preservatives not required
to inhibit the growth of bacteria in yogurt?
46. Wine is made from the juice of grapes by varieties of yeast. The yeast cells produce ethanol as a by-product of
their fermentation. However, when the ethanol concentration reaches 12-13%, all the yeast die. Explain this
observation.
Dietary Protein and Protein Digestion
47. Why is it necessary to mix vegetable proteins to provide an adequate vegetarian diet?
48. Name some ethnic foods that apply the principle of mixing vegetables proteins to provide all of the essential
amino acids.
49. What is the difference between essential and nonessential amino acids?
50. What is the difference between a complete protein and incomplete protein?
