Ch. 4- Carbon and the Molecular Diversity of Life Structure & Ch. 5- Function of Macromolecules

1. Ch. 4- Carbon and the Molecular Diversity of Life Structure & Ch. 5- Function of Macromolecules Chapters 4 and 5

2. The Uniqueness of Carbon • Requires 4 electrons to fill its outer shell. • Will form tetrahedral molecules with other atoms. Has equidistant bond angles of 109.5°. • Will readily form single, double and triple covalent bonds. • Carbon forms a variety of chained and ringed organic compounds. • Carbon is the backbone for many organic compounds.

3. Carbon in a Tetrahedron!

4. Fat droplets (stained red) 100 µm (b) Mammalian adipose cells (a) A fat molecule Figure 4.6 A, B Hydrocarbons: • Are molecules consisting of only carbon and hydrogen. • Are found in many of a cell’s organic molecules.

5. Functional groups are the parts of molecules involved in chemical reactions Functional groups • Are the chemically reactive groups of atoms within an organic molecule.

6. Six functional groups are important in the chemistry of life • Hydroxyl • Carbonyl • Carboxyl • Amino • Sulfhydryl • Phosphate • P. 64

7. OH CH3 Estradiol HO Female lion OH CH3 CH3 O Testosterone Male lion Figure 4.9 Functional groups give organic molecules distinctive chemical properties

8. Organic Compounds • Four major groups: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic Acids • Differ in their functional groups

9. Organic Compounds • Some organic compounds are small with one or a few functional groups- monomers. (Ex. Glucose = monosaccharide). • Other organic compounds are made from linking several simple monomers together in complex chains- polymers (1000’s of glucose monomers = starch, polysaccharide).

10. Monomers  Polymers SimpleComplex • Monosaccharides  Polysaccharides • Glycerol, Fatty Acids Lipids, Fats • Amino Acids  Proteins • Nucleotides  Nucleic Acids

11. Building Macromolecules • All polymers are formed by making covalent bonds between two monomers. • The –OH group from one monomer is removed and the –H from the other is removed – Dehydration Synthesis • H2O is removed which requires energy.

12. Dehydration Synthesis HO H HO H ENERGY HOH HO H

14. Dehydration Synthesis • When polymers are built from smaller monomers- anabolic reactions (synthesizing). Requires energy. • These reactions require the reactants to be held close together and chemical bonds to be stressed and broken-catalysis. • Catalysis is caused by enzymes.

15. Hydrolysis Reactions • Cells may also disassemble polymers into monomers- catabolic reactions (breakdown). • A molecule of H2O is added and split; a H is added to one monomer and the OH is added to the other-hydrolysis (water splitting). • Catabolic reactions release the energy stored in the bonds of the monomers.

17. Carbohydrates • Contain C, H, O atoms (CH2O)n • Functions: Main source of energy- for immediate use or for energy storage, Used for structure- on surfaces of cell membranes (bacteria, eukaryotes), or support cell walls (plants).

18. Three Types of Carbohydrates 1. Monosaccharides- “mono”- single; simple sugars that are made of 3-6 C’s in a chain or ring. Ex. C6H12O6 , Glucose, most abundant monosaccharide

19. Straight Chain or Rings

20. Monosaccharides- Isomers

21. H H H C H H C H H H H H H H (a) Structural isomers H C C C C C H H C C H C H H H H H H H H H X X X (b) Geometric isomers C C C C X H H H CO2H CO2H c) Enantiomers C C H H NH2 NH2 CH3 CH3 Figure 4.7 A-C Three types of isomers are: • Structural • Geometric • Enantiomers

22. L-Dopa (effective against Parkinson’s disease) D-Dopa (biologically inactive) Figure 4.8 Enantiomers: Are important in the pharmaceutical industry.

24. Isomers • Structural Isomers- monosaccharides with the same empirical formula but different structures. Ex. Glucose and Fructose • Stereoisomers – monosaccharides that have the same empirical formula but they have functional groups as mirror images of each other. • Ex. Glucose and Galactose

25. Monosaccharides of Nucleic Acids

26. Other Monosaccharides • Fructose- commonly found in fruit. • Galactose- found in milk. • Ribose- found in RNA. • Deoxyribose- found in DNA.

27. Monosaccharides • Most offer a number C-H bonds as potential chemical energy. • May also be used as monomers to build more complex polymers for energy storage or structural molecules.

28. 2. Disaccharides • Are two monosaccharides that form a glycosidic bond by removing a H2O molecule. • Glucose + Fructose-->Sucrose (table sugar)

29. Sucrose- A Disaccharide

32. Disaccharides • Monosaccharides (glucose) is often converted into a disaccharide before being transported around an organism’s body. • Unable to be usedin this form until it arrives at a tissue. • Plants transport glucose as sucrose. (sugar cane)

33. Lactose

34. Lactose • Mammals use lactose to transport glucose to infant. • Adults usually lack the enzyme, lactase, which breaks down lactose glucose + galactose.

35. Other Disaccharides • Sucrose (Table Sugar)- Glucose + Fructose • Lactose (Milk Sugar)- Glucose + Galactose • Maltose (Breakdown from Starch)- Glucose + Glucose

36. 3. Polysaccharides • Formed when monosaccharides are linked in chains by glycosidic bonds. • They are polymers- long chains of monomers (building blocks). • Polymer = polysaccharide, • Monomers = monsaccharides

37. Polysaccharides • Two Basic Functions- 1. Storage Polysaccharides: May store 1000’s of monomers for energy. Usually stored in special storage structures. 2. Structural: May form structural parts of cells and/or tissues.

38. Starch = Amylose

39. Chloroplast Starch 1 m Amylose Amylopectin (a) Starch: a plant polysaccharide Figure 5.6

40. Plant Storage- Starch • Amylose- hundreds of glucose molecules in a long, unbranched chain. • The glycosidic bond is between the 1C-4C. • The chains coil in water and don’t form H bonds, therefore not very soluble in H2O. • Only 20% of starch in potatoes is amylose. • 80% is amylopectin- short and branched glucose chains. Is cross-linked.

41. Starch Storage • Plants use special tissues called tubers. • Also stored in bulbs of perennials.

42. Mitochondria Giycogen granules 0.5 m Glycogen Figure 5.6 (b) Glycogen: an animal polysaccharide Glycogen: • Consists of glucose monomers. • Is the major storage form of glucose in animals.

43. Animal Storage- Glycogen • Insoluble, branched amylose chains. • Longer and more branched than starch. • Stored in liver and skeletal muscle. • Not transported in blood.

44. Starch Cellulose

45. H O C CH2OH CH2OH OH H C H O O OH H H H H HO C H 4 4 1 OH H OH H HO HO OH H H C OH H OH OH H C H OH  glucose C  glucose H OH (a)  and  glucose ring structures CH2OH CH2OH CH2OH CH2OH O O O O 1 4 4 4 1 1 1 OH OH OH OH O O O O HO OH OH OH OH (b) Starch: 1– 4 linkage of  glucose monomers OH OH CH2OH CH2OH O O O O OH OH OH OH 4 O 1 HO OH O O CH2OH CH2OH OH OH (c) Cellulose: 1– 4 linkage of  glucose monomers Figure 5.7 A–C Cellulose has different glycosidic linkages than starch.

46. Structural Polysaccharides • Cellulose- a chain of glucose molecules in which the monomers alternate positions. • Similar to amylose but not recognized by the same enzymes. • A water-tight, structural molecule. • Plant cell walls

47. Cellulose- A Structural Polysaccharide of Plants

48. About 80 cellulose molecules associate to form a microfibril, the main architectural unit of the plant cell wall. Cellulose microfibrils in a plant cell wall Microfibril Cell walls  0.5 m Plant cells OH OH CH2OH CH2OH O O O O OH OH OH OH O O O O O OH CH2OH OH CH2OH Cellulose molecules CH2OH OH CH2OH OH O O O O OH OH OH OH O O O Parallel cellulose molecules are held together by hydrogen bonds between hydroxyl groups attached to carbon atoms 3 and 6. O O OH CH2OH OH CH2OH CH2OH CH2OH OH OH O O O O OH OH OH OH O O O O A cellulose molecule is an unbranched  glucose polymer. O OH CH2OH OH CH2OH Figure 5.8 • Glucose monomer A major component of the tough walls that enclose plant cells

49. Figure 5.9 • Cellulose is difficult to digest: • Cows have microbes in their stomachs to facilitate this process (relationship?).

50. Polysaccharides and Clean Hair!