1. The Chemical Building Blocks of Life Chapter 3

2. 2 Biological Molecules Biological molecules consist primarily of -carbon bonded to carbon, or -carbon bonded to other molecules. Carbon can form up to 4 covalent bonds. Carbon may be bonded to functional groups with specific properties.

3. 3 Functional Groups to Know

4. 4

5. 5 Biological Molecules Isomers are molecules with the same chemical formula. -structural isomers-functional groups attached to different parts of C-skeleton -stereoisomers-different arrangements of functional groups on same C Chiral molecules are mirror-images of each other. –dextrorotatory (D form) = right-handed form –levorotatory (L-form) = left-handed form

6. 6 Isomers

7. 7 Biological Molecules

8. 8 Biological molecules are typically large molecules constructed from smaller subunits. Monomer: single subunit (mono = 1; -mer = unit) Polymer: many units (poly = many)

9. 9 Biological Molecules dehydration synthesis: formation of large molecules by the removal of water -monomers are joined to form polymers monomer +monomer -> polymer + water Hydrolysis (digestion): breakdown of large molecules by the addition of water -polymers are broken down to monomers polymer + water -> monomers

10. 10 Biological Molecules (bad artwork!)

11. 11 Dehydration synthesis: a much better graphic!

12. 12 Carbohydrates Molecules with a 1:2:1 ratio of carbon, hydrogen, oxygen -empirical formula: (CH 2 O) n -examples: sugars, starch, glucose C–H covalent bonds hold much energy Carbohydrates are good energy storage molecules.

13. 13 Carbohydrates Glucose -a monosaccharide – single sugar -contains 6 carbons (a hexose) -very important in energy storage -fructose is a structural isomer of glucose -galactose is a stereoisomer of glucose

14. 14 Carbohydrates Linear form   ring form Position of the hydroxyl (OH) group determines whether it is the alpha- or beta- form.

15. 15 Carbohydrates

16. 16 Carbohydrates Disaccharides -2 monosaccharides linked together by dehydration synthesis -used for sugar transport or energy storage -examples: sucrose, lactose, maltose

17. 17 Carbohydrates

18. 18 Carbohydrates Polysaccharides -long chains of sugars -used for energy storage -plants use starch; animals use glycogen -used for structural support -plants use cellulose -animals e.g. insects, crayfish) use chitin

19. 19 Carbohydrates

20. 20 Complex Carbohydrates: starches alpha-linkages

21. 21 Carbohydrates w/beta linkages Cellulose

22. 22 Carbohydrates: chitin

23. Reading a Food Label 23

24. 24 Nucleic Acids Two types: DNA and RNA Can you spell the full name of these? Deoxyribonucleic acid Ribonucleic acid Functions: specialized for the storage, transmission, and use of genetic information

25. 25 Nucleic Acids Nucleic acids are polymers of nucleotides. -nucleotides: sugar + phosphate + nitrogenous base -sugar is deoxyribose in DNA or ribose in RNA -Nitrogenous bases include -purines: Adenine and Guanine -pyrimidines: Thymine, Cytosine, Uracil

26. 26 Nucleotide structure

27. 27 Nucleic Acids

28. 28 Nitrogenous Bases

29. 29 Nucleic Acids DNA -nucleotides connected by phosphodiester bonds - double helix: 2 polynucleotide strands connected by hydrogen bonds -polynucleotide strands are complementary -genetic information is carried in the sequence of nucleotides

30. 30 Nucleic Acids

31. 31 Nucleic Acids RNA -contains ribose instead of deoxyribose -contains uracil instead of thymine -single polynucleotide strand -functions: -read the genetic information in DNA -direct the synthesis of proteins

32. 32 Nucleic Acids DNA RNA

33. 33 Nucleic Acids Other nucleotides -ATP: adenosine triphosphate -primary energy currency of the cell -NAD + and FAD: electron carriers for many cellular reactions

34. 34 Proteins Protein functions include: 1. enzyme catalysts 2. defense 3. transport 4. support 5. motion 6. regulation 7. storage

35. 35 Proteins Proteins are polymers of amino acids. Amino acids -20 different amino acids; we can synthesize 12 of these -joined by dehydration synthesis -peptide bonds form between adjacent amino acids

36. 36 Proteins: dehydration synthesis

37. 37 Proteins Amino acid structure -central carbon atom surrounded by -amino group -carboxyl group -single hydrogen -variable R group

38. 38 Proteins The structure of the R group dictates the chemical properties of the amino acid. Amino acids can be classified as: 1. nonpolar 2. polar 3. charged 4. aromatic 5. special function

39. 39 Proteins The shape of a protein determines its function. -primary structure – sequence of amino acids; which ones are used and in what order -secondary structure – interaction of groups in the peptide backbone -  helix -  sheet

40. 40 Proteins

41. 41 Proteins

42. 42 Proteins

43. 43 Proteins Protein structure (continued) -tertiary structure – folded shape of the polypeptide chain; e.g., a coiled coil -quaternary structure – interactions between multiple polypeptide subunits Protein folding is aided by chaperone proteins.

44. 44 Proteins

45. 45 Proteins Motifs are common elements of secondary structure seen in many polypeptides. Domains are functional regions of a polypeptide.

46. 46 Proteins

47. 47 Proteins Denaturation is a change in the shape of a protein, usually causing loss of function. -may involve complete unfolding -caused by changes in the protein’s environment -pH -temperature -salt concentration

48. 48 Protein Denaturation

49. 49 Lipids Lipids are a group of molecules that are insoluble in water (what kind of screwy definition is that?) A high proportion of nonpolar C – H bonds causes the molecule to be hydrophobic. Two main categories: -fats (triglycerides) -phospholipids

50. 50 Lipids Triglycerides (fats) -composed of 1 glycerol + 3 fatty acids Fatty acids are long hydrocarbon chains which may be -saturated -unsaturated -polyunsaturated

51. 51 Lipids: with saturated fatty acids

52. 52 Lipids: with unsaturated fatty acids

53. What are trans fats? Trans = across; cis = bent 53 Elaidic acid, the primary trans unsaturated fatty acid found in many partially hydrogenated fats Oleic acid, a cis unsaturated fatty acid making up 50- 80% of olive oil

54. More on trans fats 54 have desirable properties, e.g., a favorable melting point (30-40 degrees C) increase risk of coronary heart disease increase low-density lipoproteins (LDL), the “bad” cholesterol lower high-density lipoproteins (HDL) US Food & Drug Administration (FDA) has determined that partially hydrogenated oils (that contain trans fats) are no longer “generally recognized as safe”; this will likely lead to a ban in the near future.

55. 55 Lipids Triglycerides -an excellent molecule for energy storage -store twice as much energy as carbohydrates -animal fats are usually saturated fats and are solid at room temperature -plant fats (oils) are usually unsaturated and are liquid at room temperature

56. 56 Lipids Phospholipids -composed of: -1 glycerol -2 fatty acids -a phosphate group Phospholipids contain polar “heads” and nonpolar “tails”.

57. 57 Phospholipids: two depictions

58. 58 Lipids Phospholipids spontaneously form micelles or lipid bilayers. These structures cluster the hydrophobic regions of the phospholipid toward the inside and leave the hydrophilic regions exposed to the water environment. Lipid bilayers are the basis of biological membranes.

59. 59 Lipids

60. 60 Lipids-basis for membranes