1. UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of life

2. UNIT 1: INTRODUCING BIOLOGY Chapter 2: Chemistry of Life I. Atoms, Ions, and Molecules (2.1) A. Living things consist of atoms of different elements

3. 1. An atom is the smallest basic unit of matter 2. An element is one type of atom 3. An atom has a nucleus and electrons

4. a. The nucleus has protons and neutrons b. Electrons are in energy levels outside the nucleus

5. 4. A compound is made of atoms of different elements bonded together a. Water (H 2 0) b. Carbon dioxide (CO 2 ) c. Many other carbon-based compounds in living things.

6. B. Ions form when atoms gain or lose electrons 1. An ion is an atom that has gained or lost one or more electrons a. Positive ions -lost electron(s) b. Negative ions -gain electron(s) 2. Ionic bonds form between oppositely charged ionsIonic bonds

7. 1. A covalent bond forms when atoms share a pair of electrons a. Multiple covalent bonds b. Diatomic molecules

8. 2. A molecule is two or more atoms held together by covalent bonds

9. II. Properties of Water A. Life depends on hydrogen bonds in water 1. Water is a polar molecule a. Polar molecules have slightly charged regions

10. b. Nonpolar molecules do not have charged regions

11. c. Hydrogen bonds form between slightly positive hydrogen atoms and slightly negative atoms.

12. 2. Hydrogen bonds are responsible for three important properties of water. a. High specific heat b. Cohesion- attraction between molecules of the same substance (because of hydrogen bonds, water is very cohesive)

13. c. Adhesion- attraction between different substances. Adhesion between water and other charged or polar substances very important force. (responsible for capillary action)

14. B. Many compounds dissolve in water 1. A solution is formed when one substance dissolves in another a. A solution is a homogeneous mixture

15. b. Solvents dissolve other substances c. Solutes dissolve in a solvent

16. 2. “Like dissolves like” a. Polar solvents dissolve polar solutes b. Nonpolar solvents dissolve nonpolar solutes c. Polar substances and nonpolar substances generally remain separate

18. C. Some compounds form acids and bases 1. An acid releases a hydrogen ion when it dissolves in water a. High H+ concentration b. pH less than 7

19. 2. A base removes hydrogen ions from a solution a. low H+ concentration b. pH greater than 7

20. 3. A neutral solution has a pH of 7

22. III. Carbon-Based Molecules (2.3) A. Carbon atoms have unique bonding properties 1. Carbon forms covalent bonds with up to four other atoms, including other carbon atoms.

23. 2. Carbon-based molecules have three general types of structures a. Straight chain b. Branched chain c. Ring

24. B. Many carbon based molecules are made of many small subunits bonded together 1. Monomers are the individual subunits 2. Polymers are made of many monomers

25. B. Four main types of carbon-based molecules are found in living things. 1. Carbohydrates are made of carbon, hydrogen, and oxygen a. Carbohydrates include sugars and starches b.Monosaccharides are simple (single) sugars c. Disaccharides are double sugarsDisaccharides

26. c. Polysaccharides include starches, cellulose, and glycogen d. Carbohydrates can be broken down to provide energy for cells e. Some carbohydrates are part of cell structure

27. Fig. 5-6 (b) Glycogen: an animal polysaccharide Starch Glycogen Amylose Chloroplast (a) Starch: a plant polysaccharide Amylopectin Mitochondria Glycogen granules 0.5 µm 1 µm

28. Fig. 5-8  Glucose monomer Cellulose molecules Microfibril Cellulose microfibrils in a plant cell wall 0.5 µm 10 µm Cell walls

29. Fig. 5-10 The structure of the chitin monomer. (a) (b) (c) Chitin forms the exoskeleton of arthropods. Chitin is used to make a strong and flexible surgical thread.

30. 2. Lipids are nonpolar molecules that include fats, oils, and cholesterol a. Many contain carbon chains called fatty acids b. Fats and oils contain fatty acids bonded to glycerol.

31. Fig. 5-11 Fatty acid (palmitic acid) Glycerol (a) Dehydration reaction in the synthesis of a fat Ester linkage (b) Fat molecule (triacylglycerol)

32. Fig. 5-11b (b) Fat molecule (triacylglycerol) Ester linkage

33. c. Lipids have several different functions 1). Broken down as a source of energy 2). Make up cell membranes 3). Used to make hormones

34. d. Fats and oils have different types of fatty acids 1). Saturated fatty acids 2). Unsaturated fatty acids

35. Fig. 5-12a (a) Saturated fat Structural formula of a saturated fat molecule Stearic acid, a saturated fatty acid

36. Fig. 5-12b (b) Unsaturated fat Structural formula of an unsaturated fat molecule Oleic acid, an unsaturated fatty acid cis double bond causes bending

37. Fig. 5-12 Structural formula of a saturated fat molecule Stearic acid, a saturated fatty acid (a) Saturated fat Structural formula of an unsaturated fat molecule Oleic acid, an unsaturated fatty acid (b) Unsaturated fat cis double bond causes bending

38. e. Phospholipids make up all cell membranes 1). Polar phosphate “head” 2). Nonpolar fatty acid “tails”

39. Fig. 5-13 (b) Space-filling model (a)(c) Structural formula Phospholipid symbol Fatty acids Hydrophilic head Hydrophobic tails Choline Phosphate Glycerol Hydrophobic tails Hydrophilic head

40. Fig. 5-14 Hydrophilic head Hydrophobic tail WATER

41. 3. Proteins are polymers of amino acid monomersProteins a. Twenty different amino acids are used to build proteins in organisms

42. b. Amino acids differ in side groups, or R groups c. Amino acids are linked by peptide bonds

43. Fig. 5-21a Amino acid subunits + H 3 N Amino end 25 20 15 10 5 1 Primary Structure

44. Fig. 5-21b Amino acid subunits + H 3 N Amino end Carboxyl end 125 120 115 110 105 100 95 90 85 80 75 20 25 15 10 5 1

45. Fig. 5-19a A ribbon model of lysozyme (a) Groove

46. Fig. 5-21f Polypeptide backbone Hydrophobic interactions and van der Waals interactions Disulfide bridge Ionic bond Hydrogen bond

47. d. Proteins differ in the number and order of amino acids 1). Amino acids interact to give a protein its shape 2). Incorrect amino acids change a proteins structure and function

48. Protein Types Enzymes Contractile Defensive Hormonal Receptor Sensory Storage Structural Transport

49. 4. Nucleic acids are polymers of monomers called nucleotides a. Nucleotides are made of sugar, phosphate group, and a nitrogen base.

50. Nucleotide : Monomer of Nucleic Acids

51. b. DNA stores genetic information c. RNA builds proteins

52. Fig. 5-UN2

53. Fig. 5-UN2a

54. Fig. 5-UN2b

55. IV. Chemical Reactions (2.4) A. Bonds break and form during chemical reactions. 1. Reactants are changed during a chemical reaction 2. Products are made by a chemical reactions. C 6 H 12 O 6 + O 2 CO 2 + H 2 O reactantsproducts Cellular Respiration Photosynthesis CO 2 + H 2 O C 6 H 12 O 6 + O 2

56. B. Bond energy is the amount of energy that breaks a bond 1. Energy is added To break bonds 2. Energy is released when bonds form

57. C. A reaction is at equilibrium when reactants and products form at the same rate. CO 2 + H 2 O H 2 CO 3

58. D. Chemical reactions release or absorb energy 1. Activation energy is the amount of energy that needs to be absorbed to start a chemical reaction.

59. 2. Exothermic reactions release more energy than they absorb. a. Reactants have higher bond energy than products b. Excess energy is released by the reaction

60. 3. Endothermic reactions absorb more energy than they release. a. Reactants have lower bond energy than products a. Energy is absorbed by the reaction to make up the difference.

61. V. Enzymes (2.5) A. A catalysts lowers activation energy 1. Catalysts are substances that speed up chemical reactions a. Decrease activation energy b. Increase reaction rate

62. B. Enzymes allow chemical reactions to occur under tightly controlled conditions. 1. Enzymes are catalysts in living things a. Enzymes are needed for almost all processes b. Most enzymes are proteins

63. C. Disruptions in homeostasis can prevent enzymes from functioning. 1. Enzymes function best in a small range of conditions 2. Changes in temperature and pH can break hydrogen bonds. 3. An enzyme’s function depends on its structure

65. D. An enzyme’s structure allows only certain reactants to bind to the enzyme 1. Substrates 2. Active Site

66. E. The lock-and-key model helps illustrate how enzymes function 1. Substrates brought together 2. bonds in substrates weakened