2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemistry of Life Chapter 2 Table of Contents Section 1 Nature of Matter Section 2 Water and Solutions Section 3 Chemistry of Cells Section 4 Energy and Chemical Reactions

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 1 Nature of Matter Objectives Differentiate between atoms and elements. Analyze how compounds are formed. Distinguish between covalent bonds, hydrogen bonds, and ionic bonds. Chapter 2

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Matter Section 1 Nature of Matter Chapter 2 - Takes up space and has mass - Exists as elements (pure form) and in chemical combinations called compounds Biology is a multidisciplinary science that involves principles of chemistry, physics and mathematics.

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Atoms An atom is the smallest unit of matter that cannot be broken down by chemical means. As shown below, an atom consists of three kinds of particles: electrons, protons, and neutrons. Section 1 Nature of Matter Chapter 2 Oxygen atom (O) Nucleus: 8 protons (+) 8 neutrons outermost energy level: 6 electrons (-) inner energy level: 2 electrons (-)

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Atoms, continued Elements An element is a pure substance made of only one kind of atom. Elements differ in the number of protons their atoms contain. The number of neutrons in an atom is often but not always equal to the number of protons in the atom. Section 1 Nature of Matter Chapter 2

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Living things consist of atoms of different elements. Carbon Nitrogen Oxygen Hydrogen Hydrogen atom (H) Oxygen atom (O)

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding Atoms can join with other atoms to form stable substances. A force that joins atoms is called a chemical bond. A compound is a substance made of the joined atoms of two or more different elements. Section 1 Nature of Matter Chapter 2

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Compounds Section 1 Nature of Matter Chapter 2 O HH _ ++

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Covalent Bonds Covalent bonds form when two or more atoms share electrons to form a molecule. A molecule such as the water molecule shown below, is a group of atoms held together by covalent bonds. Section 1 Nature of Matter Chapter 2

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Molecule Section 1 Nature of Matter Chapter 2

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Covalent Bonds The arrangement of their electrons determines how atoms bond together. An atom becomes stable when its outer electron level is full. If the outer electron level is not full, an atom will react readily with atoms that can provide electrons to fill its outer level. Section 1 Nature of Matter Chapter 2

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Hydrogen Bonds In a water molecule, the shared electrons are attracted more strongly by the oxygen nucleus than by the hydrogen nuclei. Molecules with an unequal distribution of electrical charge, such as water molecules, are called polar molecules. This attraction between two water molecules is an example of a hydrogen bond—a weak chemical attraction between polar molecules. Section 1 Nature of Matter Chapter 2

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Hydrogen Bonds Water molecules are attracted to each other by hydrogen bonds. Section 1 Nature of Matter Chapter 2

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Ionic Bonds Sometimes atoms or molecules gain or lose electrons. An atom or molecule that has gained or lost one or more electrons is called an ion. Ions have an electrical charge because they contain an unequal number of electrons and protons. Ions of opposite charge may interact to form an ionic bond. Section 1 Nature of Matter Chapter 2

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Ion Section 1 Nature of Matter Chapter 2 Sodium atom (Na)Chlorine atom (CI)Sodium ion (Na + )Chloride ion (CI - ) Na loses an electron to CI ionic bond gained electron

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Chemical Bonding, continued Ionic Bonds Ionic bonds in sodium chloride, NaCl, are formed by the interaction between sodium ions, Na +, and chloride ions, Cl –. Section 1 Nature of Matter Chapter 2

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 2 Water and Solutions Objectives Analyze the properties of water. Describe how water dissolves substances. Distinguish between acids and bases. Chapter 2

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Water in Living Things Storage of Energy Many organisms release excess heat through water evaporation. In organisms, this ability to control temperature enables cells to maintain a constant internal temperature when the external temperature changes. In this way, water helps cells maintain homeostasis. Section 2 Water and Solutions Chapter 2

20. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Water in Living Things, continued Cohesion and Adhesion Cohesion is an attraction between substances of the same kind. Because of cohesion, water and other liquids form thin films and drops. Molecules at the surface of water are linked together by hydrogen bonds like a crowd of people linked by holding hands. This attraction between water molecules causes a condition known as surface tension. Section 2 Water and Solutions Chapter 2

21. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Water in Living Things, continued Cohesion and Adhesion Adhesion is an attraction between different substances. Adhesion powers a process, called capillary action, in which water molecules move upward through a narrow tube, such as the stem of a plant. Section 2 Water and Solutions Chapter 2

22. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparing Cohesion and Adhesion Section 2 Water and Solutions Chapter 2

23. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions A solution is a mixture in which one or more substances are evenly distributed in another substance. Many important substances in the body have been dissolved in blood or other aqueous fluids. Because these substances can dissolve in water, they can more easily move within and between cells. Section 2 Water and Solutions Chapter 2

24. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions, continued Polarity The polarity of water enables many substances to dissolve in water. When ionic compounds are dissolved in water, the ions become surrounded by polar water molecules. The resulting solution is a mixture of water molecules and ions. Section 2 Water and Solutions Chapter 2

25. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions, continued Polarity When sodium chloride, NaCl, is dissolved in water, sodium ions, Na +, and chloride ions, Cl –, become surrounded by water molecules, H 2 O. Section 2 Water and Solutions Chapter 2

26. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions, continued Polarity Nonpolar molecules do not dissolve well in water. The inability of nonpolar molecules to dissolve in polar molecules is important to organisms. For example, the shape and function of cell membranes depend on the interaction of polar water with nonpolar membrane molecules. Section 2 Water and Solutions Chapter 2

27. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparing Polar and Nonpolar Covalent Bonds Section 2 Water and Solutions Chapter 2

28. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions, continued Acids and Bases Compounds that form hydrogen ions when dissolved in water are called acids. When an acid is added to water, the concentration of hydrogen ions in the solution is increased above that of pure water. Section 2 Water and Solutions Chapter 2

29. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Acids Section 2 Water and Solutions Chapter 2 more acidic stomach acid pH between 1 and 3

30. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions, continued Acids and Bases Compounds that reduce the concentration of hydrogen ions in a solution are called bases. Many bases form hydroxide ions when dissolved in water. Section 2 Water and Solutions Chapter 2

31. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Bases Section 2 Water and Solutions Chapter 2 bile pH between 8 and 9 more basic

32. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Aqueous Solutions, continued Acids and Bases The pH scale measures the concentration of hydrogen ions in a solution. Section 2 Water and Solutions Chapter 2

33. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu pH Section 2 Water and Solutions Chapter 2 pure water pH 7

34. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 3 Chemistry of Cells Objectives Summarize the characteristics of organic compounds. Compare the structures and function of different types of biomolecules. Describe the components of DNA and RNA. State the main role of ATP in cells. Chapter 2

35. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds Carbohydrates Carbohydrates are organic compounds made of carbon, hydrogen, and oxygen atoms in the proportion of 1:2:1. Carbohydrates are a key source of energy, and they are found in most foods—especially fruits, vegetables, and grains. Section 3 Chemistry of Cells Chapter 2

36. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbohydrates Section 3 Chemistry of Cells Chapter 2 Polymer (starch) Starch is a polymer of glucose monomers that often has a branched structure. Polymer (cellulose) Cellulose is a polymer of glucose monomers that has a straight, rigid structure monomer

37. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Carbohydrates The building blocks of carbohydrates are single sugars, called monosaccharides, such as glucose, C 6 H 12 O 6, and fructose. Simple sugars such as glucose are a major source of energy in cells. Section 3 Chemistry of Cells Chapter 2

38. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Monosaccharides Section 3 Chemistry of Cells Chapter 2

39. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Carbohydrates Disaccharides are double sugars formed when two monosaccharides are joined. Sucrose, or common table sugar, is a disaccharide that consists of both glucose and fructose. Section 3 Chemistry of Cells Chapter 2

40. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Carbohydrates Polysaccharides such as starch are chains of three or more monosaccharides. Section 3 Chemistry of Cells Chapter 2

41. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Lipids Lipids are nonpolar molecules that are not soluble in water. They include fats, phospholipids, steroids, and waxes. Fats are lipids that store energy. A typical fat contains three fatty acids bonded to a glycerol molecule backbone. Section 3 Chemistry of Cells Chapter 2

42. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Types of Lipids Section 3 Chemistry of Cells Chapter 2 Triglyceride Phospholipid

43. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Fats Section 3 Chemistry of Cells Chapter 2

44. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Lipids In a saturated fatty acid, all of the carbon atoms in the chain are bonded to two hydrogen atoms (except the carbon atom on the end, which is bonded to three hydrogen atoms). In an unsaturated fatty acid, some of the carbon atoms are linked by a “double” covalent bond, each with only one hydrogen atom, producing kinks in the molecule. Section 3 Chemistry of Cells Chapter 2

45. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Saturated and Unsaturated Fatty Acids Section 3 Chemistry of Cells Chapter 2

46. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Proteins A protein is a large molecule formed by linked smaller molecules called amino acids. Amino acids are the building blocks of proteins. Twenty different amino acids are found in proteins. Section 3 Chemistry of Cells Chapter 2

47. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Structure of Proteins Section 3 Chemistry of Cells Chapter 2

48. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Amino Acids Section 3 Chemistry of Cells Chapter 2

49. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Amino acids interact to give a protein its s h a p e. hydrogen bond Hemoglobin – Incorrect amino acids change a protein’s structure and function.

50. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Nucleic Acids A nucleic acid is a long chain of smaller molecules called nucleotides. A nucleotide has three parts: a sugar, a base, and a phosphate group, which contains phosphorus and oxygen atoms. Section 3 Chemistry of Cells Chapter 2

51. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Nucleic Acid Section 3 Chemistry of Cells Chapter 2 A phosphate group nitrogen-containing molecule, called a base deoxyribose (sugar)

52. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Nucleotide Section 3 Chemistry of Cells Chapter 2

53. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued Nucleic Acids There are two types of nucleic acids—DNA and RNA—and each type contains four kinds of nucleotides. DNA, or deoxyribonucleic acid, consists of two strands of nucleotides that spiral around each other. RNA, or ribonucleic acid, consists of a single strand of nucleotides. Section 3 Chemistry of Cells Chapter 2

54. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Structure of Nucleic Acids Section 3 Chemistry of Cells Chapter 2

55. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu DNA Overview Section 3 Chemistry of Cells Chapter 2

56. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Ribonucleic Acid (RNA) Section 3 Chemistry of Cells Chapter 2

57. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Carbon Compounds, continued ATP ATP or adenosine triphosphate, is a single nucleotide with two extra energy-storing phosphate groups. When food molecules are broken down inside cells, some of the energy in the molecules is stored temporarily in ATP. Section 3 Chemistry of Cells Chapter 2

58. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Comparing ADP and ATP Section 3 Chemistry of Cells Chapter 2

59. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Energy and Chemical Reactions Objectives Evaluate the importance of energy to living things. Relate energy and chemical reactions. Describe the role of enzymes in chemical reactions. Identify the effect of enzymes on food molecules. Chapter 2

60. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Energy for Life Processes Energy is the ability to move or change matter. Energy exists in many forms—including light, heat, chemical energy, mechanical energy, and electrical energy—and it can be converted from one form to another. Energy can be stored or released by chemical reactions. Section 4 Energy and Chemical Reactions Chapter 2

61. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Energy for Life Processes, continued Energy in Chemical Reactions In chemical reactions, energy is absorbed or released when chemical bonds are broken and new ones are formed. Metabolism is the term used to describe all of the chemical reactions that occur within an organism. Exothermic reactions release more energy than they absorb. Endothermic reactions absorb more energy than they release. Section 4 Energy and Chemical Reactions Chapter 2

62. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Energy and Chemical Reactions Section 4 Energy and Chemical Reactions Chapter 2

63. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Energy for Life Processes, continued Activation Energy The energy needed to start a chemical reaction is called activation energy. Activation energy is simply a chemical “push” that starts a chemical reaction. Even in a chemical reaction that releases energy, activation energy must be supplied before the reaction can occur. Section 4 Energy and Chemical Reactions Chapter 2

64. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu

65. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Enzymes Enzymes are substances that increase the speed of chemical reactions. Most enzymes are proteins. Enzymes are catalysts, which are substances that reduce the activation energy of a chemical reaction. An enzyme increases the speed of a chemical reaction by reducing the activation energy of the reaction. Section 4 Energy and Chemical Reactions Chapter 2

66. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Enzymes, continued Enzyme Specificity A substance on which an enzyme acts during a chemical reaction is called a substrate. Enzymes act only on specific substrates. An enzyme’s shape determines its activity. Typically, an enzyme is a large protein with one or more deep folds on its surface. These folds form pockets called active sites. Section 4 Energy and Chemical Reactions Chapter 2

67. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Enzymes, continued Enzyme Specificity An enzyme acts only on a specific substrate because only that substrate fits into its active site. Step 1 When an enzyme first attaches to a substrate, the enzyme’s shape changes slightly. Step 2 At an active site, an enzyme and a substrate interact, reducing the reaction’s activation energy. Step 3 The reaction is complete when products have formed. Section 4 Energy and Chemical Reactions Chapter 2

68. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Enzyme Activity Section 4 Energy and Chemical Reactions Chapter 2

69. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Enzymes, continued Factors in Enzyme Activity Any factor that changes the shape of an enzyme can affect the enzyme’s activity. Temperature and pH value can alter an enzymes effectiveness. The enzymes that are active at any one time in a cell determine what happens in that cell. Section 4 Energy and Chemical Reactions Chapter 2

70. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Factors Affecting Reaction Rate Section 4 Energy and Chemical Reactions Chapter 2

71. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice Use the figure below to answer questions 1–3. Standardized Test Prep Chapter 2

72. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 1.The molecule shown in the diagram is A.cellulose B.DNA C.RNA D.ATP Standardized Test Prep Chapter 2

73. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 1.The molecule shown in the diagram is A.cellulose B.DNA C.RNA D.ATP Standardized Test Prep Chapter 2

74. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 2.What is the main function of this molecule? F.promoting chemical reactions G.making up cell membranes H.storing energy J. storing hereditary information Standardized Test Prep Chapter 2

75. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 2.What is the main function of this molecule? F.promoting chemical reactions G.making up cell membranes H.storing energy J. storing hereditary information Standardized Test Prep Chapter 2

76. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 3. What do the dashed lines in the drawing represent? A.nuclear bonds B.covalent bonds C.hydrogen bonds D.ionic bonds Standardized Test Prep Chapter 2

77. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Multiple Choice, continued 3. What do the dashed lines in the drawing represent? A.nuclear bonds B.covalent bonds C.hydrogen bonds D.ionic bonds Standardized Test Prep Chapter 2