1. Proteins

3. PROTEINS

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

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. Understanding: There are 20 different amino acids
in polypeptides synthesized on ribosomes.

9. “Essential Amino Acids” are those that must be ingested in the diet (our body can’t make them)
Chart for reading amino acids
Amino acid name – abb - Letter
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

10. 02
Understandings:
Amino acids are linked together by condensation to form Polypeptides

11. 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

12. Condensation

14. Understanding: Amino acids can be linked together in any sequence, giving a huge range of possible polypeptides

15. Understanding: A protein may consist of a single Polypeptide or more than one polypeptide linked together

16. The amino acid sequence determines the
three - dimensional conformation of a protein.

17. Proteins have four levels of organization

18. Primary structure is the amino acid sequence

19. Understanding: The amino acid sequence of
polypeptides is coded for by DNA (genes) and is
unique for each kind of protein.

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

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

24. Proteins have four levels of organization

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

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

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

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

31. Proteins have four levels of organization

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

35. 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

37. Types of interactions
Hydrogen bonds between polar side chains

39. Types of interactions
Ionic bonds between positively and negatively charged side chains

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

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

45. 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

46. Application: Denaturation of proteins by heat or by deviation of pH from the optimum
May be due to changes in: pH
Temperature
Various chemicals

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

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

51. Living organisms synthesize many different proteins with a wide range of functions.

60. Folded proteins are placed into two general categories

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

62. 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

65. 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

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

67. Functions of globular proteins
Storage proteins function in the storage of amino acids
Ovalbumin is the proteins in egg whites
Casein is the protein in milk, source of amino acids for baby mammals

69. Functions of globular proteins
Transport proteins function in the movement of other substances
Haemoglobin, the iron containing protein in blood, transport oxygen from lungs to other parts of the body (C3032H4816O872N780S9Fe4)
Membrane transport proteins such as channels for potassium and water

71. 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)

73. 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

74. Functions of globular proteins
Cholesterol receptors on the cell membrane allow LDL to be endocytosed into the cell

75. Functions of globular proteins
Protective proteins function as protection against disease
Antibodies combat bacteria and viruses

76. Functions of globular proteins
Enzymes speed up chemical reactions
Amylase and other digestive enzymes hydrolyze polymers in food
Catalase converts hydrogen peroxide H2O2 into water and oxygen gas during cellular respiration

77. Active Genes Depends what type of cell they are
Number of active genes varies by organism
Common name of the organism
Approximate number of genes in the organism’s genome
Yeast (single-celled fungi)
6,000
Drosophila (fruit fly)
14,000
Rice plant
51,000
Laboratory mouse
30,000
Domestic dog
19,000
Humans
20-25,000
Number does not correlate to complexity

78. Understanding: Every individual has a unique
proteome.