Chapter 2 pt 3

1. Atoms, Molecules, and Life Chapter 2pt 3

2. 2.5 How Are Biological Molecules Joined Together Or Broken Apart? • Biomolecules are polymers (chains) of subunits called monomers • A huge number of different polymers can be made from a small number of monomers • Biomolecules Are Joined Through Dehydration and Broken by Hydrolysis

3. Organic Molecule Synthesis • Monomers are joined together through dehydration synthesis • An H and an OH are removed, resulting in the loss of a water molecule (H2O)

5. Organic Molecule Synthesis • Polymers are broken apart through hydrolysis (“water cutting”) • Water is broken into H and OH and used to break the bond between monomers

7. Organic Molecule Synthesis • All biological molecules fall into one of four categories • Carbohydrates • Lipids • Proteins • Nucleic Acids

10. 2.6 What Are Carbohydrates? • Composition: C, H, and O in the ratio of 1:2:1 • Construction: • Simple or single sugars are monosaccharides • Two linked monosaccharides are disaccharides • Long chains of monosaccharides are polysaccharides

11. Monosaccharides • Basic monosaccharide structure • Backbone of 3-7 carbon atoms • Many –OH and –H functional groups • Usually found in a ring form in cells • Simple sugars provide important energy sources for organisms. • Most small carbs are water-soluble due to the polar OH functional groups

12. A simple sugar CH2OH H O H H H H O H H H 3 2 1 6 5 4 C C C C C C H H OH HO OH H O O O O O H H H H H H OH (a) (b) Glucose, linear form Glucose, ring form Fig. 2-13

14. Monosaccharides • Example monosaccharides continued • Fructose (found in corn syrup and fruits) • Galactose (found in lactose) • Ribose and deoxyribose (found in RNA and DNA)

17. Most small carbs are water-soluble due to the polar OH functional groups

18. Disaccharides • Disaccharides are two-part sugars • Sucrose (table sugar) = glucose + fructose • Lactose (milk sugar) = glucose + galactose • Maltose (malt sugar)= glucose + glucose

19. Manufacture of a disaccharide glucose fructose sucrose CH2OH CH2OH O O O O HOCH2 HOCH2 H H H H H H H H + dehydrationsynthesis O H OH H HO OH H HO H HO O H CH2OH CH2OH HO HO OH H OH H OH H H OH O H H Fig. 2-14

20. Polysaccharides • Monosaccharides are linked together to form chains (polysaccharides) • Polysaccharides are used for energy storage and structural components

21. Polysaccharides • Storage polysaccharides • Starch (polymer of glucose) • Formed in roots and seeds as a form of glucose storage • Glycogen (polymer of glucose) • Found in liver and muscles

24. Polysaccharides • Structural polysaccharides • Cellulose (polymer of glucose) • Found in the cell walls of plants • Indigestible for most animals due to orientation of bonds between glucoses

30. Polysaccharides • Structural polysaccharides continued • Chitin (polymer of modified glucose units) • Found in the outer coverings of insects, crabs, and spiders • Found in the cell walls of many fungi

32. 2.7 What Are Lipids? • Molecular characteristics of lipids • Lipids are molecules with long regions composed almost entirely of carbon and hydrogen. • The nonpolar regions of carbon and hydrogen bonds make lipids hydrophobic and insoluble in water.

33. What Are Lipids? • Lipids are diverse in structure and serve in a variety of functions • Energy storage • Waterproofing • Membranes in cells • Hormones

34. Lipid classification • Group 1: Oils, fats, and waxes • Group 2: Phospholipids • Group 3: Steroids

35. Group 1: Oils, fats, and waxes • Formed by dehydration synthesis • 3 fatty acids + glycerol  triglyceride • Contain only carbon, hydrogen, and oxygen • Contain one or more fatty acid subunits in long chains of C and H with a carboxyl group(–COOH) • Ring structure is rare

36. Group 1: Oils, fats, and waxes (continued) • Fats and oils form by dehydration synthesis from three fatty acid subunits and one molecule of glycerol. etc. CH2 CH2 CH2 H O CH H OH HO C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH C O + H OH etc. C HO C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 O H OH etc. C HO C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 H fatty acids glycerol Fig. 2-16

37. Group 1: Oils, fats, and waxes (continued) • Fats and oils formed by dehydration synthesis are called triglycerides. • Triglycerides are used for long-term energy storage in both plants and animals. etc. CH2 CH2 CH2 O H O CH + H H H C O C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH O O + H H etc. H C O C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 O O + etc. H C O C CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 H H H 3 watermolecules triglyceride Fig. 2-16

39. Group 1: Oils, fats, and waxes (continued) • Characteristics of fats • Solidity is due to the prevalence of single or double carbon bonds • Fats are solid at room temperature. • Fats have all carbons joined by single covalent bonds. • The remaining bond positions on the carbons are occupied by hydrogen atoms.

40. Group 1: Oils, fats, and waxes (continued) • Fatty acids of fats are said to be saturated and are straight molecules that can be stacked. (a) Beef fat (saturated) Fig. 2-18a

41. Group 1: Oils, fats, and waxes (continued) • Characteristics of oils • Oils are liquid at room temperature. • Some of the carbons in fatty acids have double covalent bonds. • There are fewer attached hydrogen atoms, and the fatty acid is said to be unsaturated.

42. Group 1: Oils, fats, and waxes (continued) • Unsaturated fatty acids have bends and kinks in fatty acid chains and can’t be stacked. (b) Peanut oil (unsaturated) Fig. 2-18b

43. Group 1: Oils, fats, and waxes (continued) • Characteristics of waxes • Waxes are solid at room temperature. • Waxes are highly saturated. • Waxes are not a food source. • Waxes are composed of long hydrocarbon chains and are strongly hydrophobic

44. Group 1: Oils, fats, and waxes (continued) • Waxes form waterproof coatings • Leaves and stems of plants • Fur in mammals • Insect exoskeletons • Used to build honeycomb structures

45. Group 1: Oils, fats, and waxes (continued) • Bees use waxes to store food and honey. Fig. 2-17b

46. Group 2: Phospholipids Phospholipids: form dual layered plasma membranes around all cells • Construction • like oils except one fatty acid is replaced by a phosphate group attached to glycerol. • 2 fatty acids + glycerol + a short polar functional group • water-soluble heads and water-insoluble tails.

47. Group 2: Phospholipids (continued) • The phosphate end of the molecule is water soluble; the fatty acid end of the molecule is water insoluble. CH3 CH2 CH2 CH2 CH3 O– CH2 CH2 CH2 H3C - N+ - CH2 - CH2 - O - P - O - CH2 O CH2 CH O HC - O - C - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH CH3 O H2C - O - C - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH2 - CH3 polar head glycerol fatty acid tails (hydrophilic) (hydrophobic) Fig. 2-19

48. Group 3: Steroids • Steroids contain four fused carbon rings. • Various functional groups protrude from the basic steroid “skeleton”. • Examples of steroids • Cholesterol • Found in membranes of animal cells • Male and female sex hormones

50. 2.8 What Are Proteins? • Functions of proteins • Proteins act as enzymes to catalyze (speed) many biochemical reactions. • They provide structure (ex/ elastin) • They can act as energy stores. • They are involved in carrying oxygen around the body (hemoglobin). • They are involved in muscle movement.