1. PROTEINS

2. Proteins Proteins do the nitty-gritty jobs of every living cell. Proteins are made of long strings of individual building blocks known as amino acids.

3. Amino acids contain an amino group, a carboxyl group, a carbon and a unique R group

4. 3.2.2 Identify amino acids... from diagrams showing their structure.

5. Polar R groups make the amino acid hydrophilic Non-polar R groups make the amino acid hydrophobic

6. Ionic R groups make the amino acid hydrophilic

7. 7.5.3 Explain the significance of polar and non-polar amino acids.

8. There are 20 commonly occurring amino acids that are found in proteins alanine - ala - A arginine - arg - R *** asparagine - asn - N aspartic acid - asp - D cysteine - cys - C glutamine - gln - Q glutamic acid - glu - E glycine - gly - G histidine - his - H *** isoleucine - ile - I leucine - leu - L lysine - lys - K methionine - met - M phenylalanine - phe - F proline - pro - P serine - ser - S threonine - thr - T tryptophan - trp - W tyrosine - tyr - Y valine - val - V “Essential Amino Acids” are those that must be ingested in the diet (our body can’t make them)

9. Peptide Bonds join amino acids It’s a condensation reaction (meaning that H20 is released when the bond is formed). Two amino acids form a DI-PEPTIDE POLYPEPTIDES are formed from more than two amino acids bonded together

11. 3.2.5 Outline the role of condensation and hydrolysis in the relationships between … amino acids and polypeptides. 7.4.5 Draw and label a diagram showing the structure of a peptide bond between two amino acids.

12. Proteins have four levels of organization

13. Primary structure is the amino acid sequence

14. The amino acid sequence is coded for by DNA and is unique for each kind of protein

15. The amino acid sequence determines how the polypeptide will fold into its 3D shape

16. Even a slight change in the amino acid sequence can cause the protein to malfunction For example, mis-formed hemoglobin causes sickle cell disease

17. Proteins have four levels of organization

18. Secondary structure results from hydrogen bonding between the oxygen of one amino acid and the hydrogen of another

20. The alpha helix is a coiled secondary structure due to a hydrogen bond every fourth amino acid

23. The beta pleated sheet is formed by hydrogen bonds between parallel parts of the protein

25. A single polypeptide may have portions with both types of secondary structure

26. Proteins have four levels of organization

28. Tertiary structure depends on the interactions among the R group side chains

30. Types of interactions Hydrophobic interactions: amino acids with nonpolar side chains cluster in the core of the protein, out of contact with water = charged = hydrophobic

32. Types of Interactions Hydrogen bonds between polar side chains

34. Types of Interactions Ionic bonds between positively and negatively charged side chains

36. Types of interactions Disulfide bridge (strong covalent bonds) between sulfur atoms in the amino acid cysteine

38. Proteins have four levels of organization

39. Quaternary structure results from interactions among separate polypeptide chains.

40. For example, hemoglobin is composed of 4 polypeptide chains Link to video

41. Proteins have four levels of organization

42. The folding of proteins is aided by other proteins, called chaperones Act as temporary braces as proteins fold into their final conformation Research into chaperones is a area of research in biology

44. 7.5.1 Explain the four levels of protein structure, indicating the significance of each level.

45. Denaturation results in disruption of the secondary, tertiary, or quaternary structure of the protein

46. Denaturation may be due to changes in pH, temperature or various chemicals –

47. Protein function is lost during denaturation, which is often irreversible

48. 3.6.4 Define denaturation.

49. Folded proteins are placed into two general categories

50. Fibrous proteins have polypeptide chains organized in long fibers or sheets Water insoluble Very tough physically, may be stretchy

51. Functions of Fibrous Proteins Structural proteins function in support –Insects and spiders use silk fibers to make cocoons and webs –Collagen and elastin are used in animal tendons and ligaments –Keratin is the protein in hairs, horns and feathers

54. Functions of Fibrous Proteins Contractile proteins function in movement –Actin and myosin contract to create the cleavage furrow and to move muscles –Contractile proteins move cilia and flagella

55. Globular proteins have their chains folded into compact, rounded shapes Easily water soluble

56. Functions of Globular Proteins Storage proteins function in the storage of amino acids –Ovalbumin is the protein in egg whites –Casein is the protein in milk, source of amino acids for baby mammals

58. Functions of Globular Proteins Transport proteins function in the movement of other substances –Hemoglobin, the iron containing protein in blood, transport oxygen from lungs to other parts of the body (C 3032 H 4816 O 872 N 780 S 9 Fe 4 ) –Membrane transport proteins such as channels for potassium and water

60. Functions of Globular Proteins Hormone proteins function as cellular messenger molecules that help maintain homeostasis –Insulin: sends message “allow sugar into cells” (when blood glucose levels are high, cells will transport glucose into the cells for use or storage) –Glucagon: sends message “we need more sugar in the blood” (when blood glucose is too low, cells will release glucose)

62. Functions of Globular Proteins Receptor proteins allow cells to respond to chemical stimuli –Growth factor receptors initiate the signal transduction pathway when a growth hormone attaches

63. Functions of Globular Proteins –Cholesterol receptors on the cell membrane allow LDL to be endocytosed into the cell

64. Functions of Globular Proteins Protective proteins function as protection against disease –Antibodies combat bacteria and viruses

65. Functions of Globular Proteins Enzymes speed up chemical reactions –Amylase and other digestive enzymes hydrolyze polymers in food –Catalase converts hydrogen peroxide H 2 O 2 into water and oxygen gas during cellular respiration

72. 7.5.2 Outline the difference between fibrous and globular proteins, with reference to two examples of each protein type. 7.5.4 State four functions of proteins, giving a named example of each.