1. Bio 134 Ch. 6

2. 6.1 Atoms, Elements, and Compounds P. 148-155

3. Main Idea Matter is composed of tiny particles called atoms

4. Atom Building blocks of matter

5. Structure of an Atom Nucleus – the center of the atom where protons and neutrons are located Protons – positively charged particles Neutrons – particles that have no charge Electrons – negatively charged particles located around the nucleus

7. Inside an Atom

8. Element A pure substance that cannot be broken down into other substances by physical or chemical means Are made of 1 type of atom

10. Isotopes Atoms of the same element that have different numbers of neutrons Add the number of protons and neutrons

11. Compounds Are a pure substance formed when two or more different elements combine H 2 O –2 hydrogens, 1 oxygen

12. What are 2 characteristics of compounds? 1. Always formed in a fixed ratio –Example: Water – H 2 O – always has 2 H for every 1 O 2. Can only be broken down into specific parts by a chemical reaction

13. Chemical Bond The force that hold two substances together –Example: water (H 2 O), salt(NaCl), methane (CH 4 )

14. Chemical Bond They travel around the nucleus in areas called energy levels A partially filled energy level is not stable. Atoms become more stable by losing e- or attracting e- from other atoms

15. Covalent Bonds a chemical bond that forms when e- are shared

16. Molecule Substances with covalent bonds –Example: water (H 2 O) Covalent bonds can be single (sharing only 1 pair of e-) double (sharing 2 pairs of e-) or triple (sharing 3 pairs of e-)

17. Ionic Bond Ion – an atom that has lost or gained one or more electrons and has a positive or negative charge Ionic Bonds – when + charged ions bond with – charged ions

18. NaCl Ionic Bond

19. Van der Waals Forces  When molecules come close together, the attractive forces between slightly positive and negative regions pull on the molecules and hold them together.  The strength of the attraction depends on the size of the molecule, its shape, and its ability to attract electrons

20. End of 6.1

21. 6.2 Chemical Reactions p. 156 - 160

22. Main Idea Chemical reactions allow living things to grow, develop, reproduce, and adapt

23. Reactants and Products Chemical reaction – the process by which atoms or groups of atoms in substances are reorganized into different substances -Chemical bonds are broken down or formed

24. How do you know a chemical reaction has taken place? Color change Production of heat Production of light Formation of a gas, solid, or liquid

25. Example of a chemical reaction:

26. Chemical Equations Reactants – the starting products are always on the left side of the arrow Products – the substances formed during the reaction are always on the right side of the arrow Reactants  Products

27. Balanced Equations Law of Conservation of Mass – states that matter can not be created nor destroyed The number of atoms of each element on the reactant side must be equal to the number of atoms of the same element on the products side

28. Why do we balance chemical equations? Because matter can not be created nor destroyed

29. Paper Burning Demo

30. Paper Burning Check… How do we know a reaction took place? What happened when we covered the paper with the glass cover? What was needed in order for the paper to burn?

31. Energy of Reactions Activation Energy – the minimum amount of energy needed for reactants to form products in a chemical reaction –Example – a candle will not burn until you light the wick, the flame provides the activation energy for the reaction of the substances in the candle

32. Types of Reactions Exothermic reactions – it releases energy in the form of heat

33. Types of Reactions Endothermic reactions – it absorbs heat energy

34. Back to Paper burning… What was the activation energy that started the reaction of the paper burning? Was it an endothermic or exothermic reaction?

35. Enzymes Catalyst – a substance that lowers the activation energy needed to start a chemical reaction Enzymes – are biological catalysts that speed up the rate of chemical reactions in biological processes

36. Enzyme Activity

37. Substrates – the reactants that bind to the enzyme Active site – the specific location where a substrate binds on an enzyme

38. Substrates and Active Sites

39. What are the factors that affect Enzyme Activity? pH Temperature Other substances

40. End of 6.2

41. 6.3 Water and Solutions P. 162 - 165

42. Why is water so important in Biology?

43. Main Idea The properties of water make it well suited to help maintain homeostasis in an organism

44. Polar molecule Molecles that have an unequal distribution of charges and have oppositely charged regions Example of polarity – the reason water and oil don’t mix – water is polar and oil is not

45. Example of polarity – Water and Oil

46. Hydrogen bond A weak interaction ivolving a hydrogen atom and a F, O, or N atom Is a strong type of van der Waals interaction

47. Hydrogen Bonding

48. Mixture Combination of two or more substances in which each substance retains its individual characteristics Examples of mixtures:

50. Homogeneous mixture A mixture that has a uniform composition throughout Examples:

52. Solution When all of the components are evenly distributed throughout –Example: saltwater

53. Solvent The substance in which another substance is dissolved Example: water

54. Solute The that is dissolved in the solvent Example: salt

55. Heterogenous mixture The components remain distinct, you can tell what they are individually Example: a salad – has lettuce, vegetables, dressing – each ingredient remains independent

57. Suspension When a particles in a liquid are not dissolved, and remain moving

59. Colloid a heterogeneous mixture in which the particles do not settle out –Example – milk – protein and fat don’t settle out

61. Blood Solution – blood is a solution because it has many dissolved particles in it Suspension – blood is a suspension because it has many particles suspended in it such as cells

62. Acids and Bases Acid – substances that release Hydrogen ions (H+) when dissolved in water Base – substances that release hydroxide ions (OH-) when dissolved in water

63. pH The measure of concentration of H+ in a solution pH of pure water is 7 (neutral) pH of lower than 7 are acidic –have more H+ pH of higher than 7 are basic –-have more OH-

64. pH Scale

65. Buffers Mixtures that can react with acids or bases to keep the pH within a particular range In cells, buffers keep the range between 6.5 and 7.5 In blood, buffers keep the range at about 7.4

66. End of 6.3

67. 6.4 The Building Blocks of Life p. 166 - 171

68. How does Chemistry relate to Biology?

69. Main Idea Organisms are made of carbon-based molecules

70. Organic Chemistry Carbon can form covalent bonds with 4 other atoms, including other carbons Can form straight chains, branched chains, and rings

71. Macromolecules large molecules that are formed by joining smaller organic molecules together

72. Polymers Molecules made from repeating unit of identical or nearly identical compounds linked together by a series of covalent bonds Poly means many

73. P. 167 Use table 6.1 and list examples and functions of the 4 biological macromolecues

74. Carbohydrates Compounds composed of carbon, hydrogen, and oxygen in a ratio of 1O, 2H, 1C (CH 2 O) n – n is the number of units in the chain

75. Carbohydrate functions Energy source – monosaccharide, disaccharide, sucrose (table sugar), lactose (in milk) Structural support –in plants, cellulose provides support in cell walls –In animals Chitin is a polysaccharide that is the main component in the hard outer shell of shrimp, lobsters, and some insects and fungi

76. Lipids Molecules made mostly of carbon and hydrogen that make up fats, oils, and waxes Primary function is to store energy –In animals, stored in fat cells –In plants, used as waxy coating on some leaves

77. p. 169 Use your textbook to describe the following: –Saturated fats –Unsaturated fats –Polyunsaturated fats

78. Types of fats –Saturated fats - Lipids that have tail chains with only single bonds between the carbon atoms –Unsaturated fats - Lipids that have at least one double bond between carbon atoms –Polyunsaturated fats - Fats with more than one double bond in the tail

79. Other Lipids Phospholipid - Responsible for the structure and function of the cell membrane, serves as a barier in biological membranes Steroid – examples: cholesterol and hormones such as estrogen and testosterone

80. Proteins A compound made of small carbon compounds called amino acids

81. Amino acids Small compounds that are made of carbon, nitrogen, oxygen, hydrogen, and sometimes sulfer

82. Amino Acid Structure Have a central carbon atom An amino group (H 2 N) A H atom A variable group – this makes each one different (20 different groups)

83. 3-D structure Proteins have up to 4 levels of structure: –Primary structure - # of amino acids in a chain and the order they are in –Secondary structure – folds into a uinque 3-d shape (helix and pleat) –Tertiary structure – globular or long fibers –4 th level – combining with other proteins

84. Nucleic Acid Complex macromolecules that store and transmit genetic information Made of smaller nucleotides

85. Nucleotides Composed of carbon, nitrogen, oxygen, phosphorus, and hydrogen atoms 6 major nucleotides

86. DNA and RNA Nucleic acids found in living organisms

87. ATP The storehouse of chemical energy that can be used by the cells

88. End of 6.4

89. End of Ch. 6