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1 How to Use This Presentation
To View the presentation as a slideshow with effects select “View” on the menu bar and click on “Slide Show.” To advance through the presentation, click the right-arrow key or the space bar. From the resources slide, click on any resource to see a presentation for that resource. From the Chapter menu screen click on any lesson to go directly to that lesson’s presentation. You may exit the slide show at any time by pressing the Esc key.

2 Standardized Test Prep
Resources Chapter Presentation Visual Concepts Transparencies Standardized Test Prep

3 Chapter 2 Table of Contents Section 1 Nature of Matter
Chemistry of Life Table of Contents Section 1 Nature of Matter Section 2 Water and Solutions Section 3 Chemistry of Cells Section 4 Energy and Chemical Reactions

4 Chapter 2 Objectives Differentiate between atoms and elements.
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.

5 Chapter 2 Section 1 Nature of Matter Matter

6 Chapter 2 Section 1 Nature of Matter 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.

7 Chapter 2 Section 1 Nature of Matter Atoms An atom is the smallest unit of matter that cannot be broken down by _________ means. As shown below, an atom consists of three kinds of particles: electrons, ________, and neutrons.

8 Chapter 2 Section 1 Nature of Matter Atom

9 Chapter 2 Atoms, continued Elements
Section 1 Nature of Matter 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.

10 Chapter 2 Atoms, continued Elements
Section 1 Nature of Matter Atoms, continued Elements An element is a pure substance made of only one kind of ____. Elements differ in the number of _______ their atoms contain. The number of neutrons in an atom is often but not always equal to the number of protons in the atom.

11 Chapter 2 Section 1 Nature of Matter Element

12 Chapter 2 Chemical Bonding
Section 1 Nature of Matter 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.

13 Chapter 2 Chemical Bonding
Section 1 Nature of Matter Chemical Bonding Atoms can join with other atoms to form stable substances. A force that joins atoms is called a ________ bond. A ________ is a substance made of the joined atoms of two or more different elements.

14 Chapter 2 Section 1 Nature of Matter Compounds

15 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter 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.

16 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Covalent Bonds Covalent bonds form when two or more atoms _____ electrons to form a molecule. A molecule such as the water molecule shown below, is a group of atoms held together by covalent bonds.

17 Chapter 2 Section 1 Nature of Matter Molecule

18 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter 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.

19 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Covalent Bonds The arrangement of their electrons determines how atoms bond together. An atom becomes stable when its _____ 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.

20 Chapter 2 Section 1 Nature of Matter Covalent Bonding

21 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter 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.

22 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Hydrogen Bonds In a water molecule, the shared electrons are attracted more strongly by the ______ nucleus than by the hydrogen nuclei. Molecules with an unequal distribution of electrical charge, such as water molecules, are called _____ molecules. This attraction between two water molecules is an example of a hydrogen bond—a weak chemical attraction between polar molecules.

23 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Hydrogen Bonds Water molecules are attracted to each other by hydrogen bonds.

24 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Hydrogen Bonds Water molecules are attracted to each other by ________ bonds.

25 Chapter 2 Section 1 Nature of Matter Hydrogen Bonding

26 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter 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.

27 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter 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 ________ charge may interact to form an ionic bond.

28 Chapter 2 Section 1 Nature of Matter Ion

29 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Ionic Bonds Ionic bonds in sodium chloride, NaCl, are formed by the interaction between sodium ions, Na+, and chloride ions, Cl–.

30 Chemical Bonding, continued
Chapter 2 Section 1 Nature of Matter Chemical Bonding, continued Ionic Bonds Ionic bonds in sodium chloride, ____, are formed by the interaction between sodium ions, Na+, and chloride ions, Cl–.

31 Chapter 2 Section 1 Nature of Matter Ionic Bonding

32 Chapter 2 Objectives Analyze the properties of water.
Section 2 Water and Solutions Objectives Analyze the properties of water. Describe how water dissolves substances. Distinguish between acids and bases.

33 Chapter 2 Water in Living Things Storage of Energy
Section 2 Water and Solutions 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.

34 Chapter 2 Water in Living Things Storage of Energy
Section 2 Water and Solutions Water in Living Things Storage of Energy Many organisms release excess heat through water _________. 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 ___________.

35 Water in Living Things, continued
Chapter 2 Section 2 Water and Solutions 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.

36 Water in Living Things, continued
Chapter 2 Section 2 Water and Solutions Water in Living Things, continued Cohesion and Adhesion Cohesion is an attraction between substances of the ____ 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.

37 Water in Living Things, continued
Chapter 2 Section 2 Water and Solutions 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.

38 Water in Living Things, continued
Chapter 2 Section 2 Water and Solutions Water in Living Things, continued Cohesion and Adhesion Adhesion is an attraction between _________ 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.

39 Comparing Cohesion and Adhesion
Chapter 2 Section 2 Water and Solutions Comparing Cohesion and Adhesion

40 Chapter 2 Aqueous Solutions
Section 2 Water and Solutions 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.

41 Chapter 2 Aqueous Solutions
Section 2 Water and Solutions Aqueous Solutions A solution is a mixture in which one or more substances are ______ 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.

42 Solutes, Solvents and Solutions
Chapter 2 Section 2 Water and Solutions Solutes, Solvents and Solutions

43 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions 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.

44 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Polarity The polarity of water enables many substances to ________ 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.

45 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Polarity When sodium chloride, NaCl, is dissolved in water, sodium ions, Na+, and chloride ions, Cl–, become surrounded by water molecules, H2O.

46 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Polarity When sodium chloride, NaCl, is _________ in water, sodium ions, Na+, and chloride ions, Cl–, become surrounded by water molecules, H2O.

47 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions 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.

48 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Polarity Nonpolar molecules do ___ 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.

49 Comparing Polar and Nonpolar Covalent Bonds
Chapter 2 Section 2 Water and Solutions Comparing Polar and Nonpolar Covalent Bonds

50 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions 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.

51 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Acids and Bases Compounds that form hydrogen ions when dissolved in water are called _____. When an acid is added to water, the concentration of hydrogen ions in the solution is increased above that of pure water.

52 Chapter 2 Section 2 Water and Solutions Acids

53 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions 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.

54 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Acids and Bases Compounds that reduce the concentration of hydrogen ions in a solution are called _____. Many bases form hydroxide ions when dissolved in water. The __ scale measures the concentration of hydrogen ions in a solution.

55 Chapter 2 Section 2 Water and Solutions Bases

56 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Acids and Bases The pH scale measures the concentration of hydrogen ions in a solution.

57 Aqueous Solutions, continued
Chapter 2 Section 2 Water and Solutions Aqueous Solutions, continued Acids and Bases The __ scale measures the concentration of hydrogen ions in a solution.

58 Chapter 2 Section 2 Water and Solutions pH

59 Chapter 2 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.

60 Chapter 2 Carbon Compounds Carbohydrates
Section 3 Chemistry of Cells 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.

61 Chapter 2 Carbon Compounds Carbohydrates
Section 3 Chemistry of Cells 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 ______, and they are found in most foods—especially fruits, vegetables, and grains.

62 Chapter 2 Section 3 Chemistry of Cells Carbohydrates

63 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Carbohydrates The building blocks of carbohydrates are single sugars, called monosaccharides, such as glucose, C6H12O6, and fructose. Simple sugars such as glucose are a major source of energy in cells.

64 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Carbohydrates The building blocks of carbohydrates are single sugars, called monosaccharides, such as _______, C6H12O6, and fructose. Simple sugars such as glucose are a major source of energy in cells.

65 Chapter 2 Section 3 Chemistry of Cells Monosaccharides

66 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

67 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Carbohydrates Disaccharides are double sugars formed when two monosaccharides are joined. _______, or common table sugar, is a disaccharide that consists of both glucose and fructose.

68 Chapter 2 Section 3 Chemistry of Cells Disaccharides

69 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Carbohydrates Polysaccharides such as starch, shown below, are chains of three or more monosaccharides.

70 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Carbohydrates Polysaccharides such as ______, shown below, are chains of three or more monosaccharides.

71 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

72 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Lipids Lipids are nonpolar molecules that are not soluble in water. They include ____, phospholipids, steroids, and waxes. Fats are lipids that store energy. A typical fat contains three fatty acids bonded to a glycerol molecule backbone.

73 Chapter 2 Section 3 Chemistry of Cells Types of Lipids

74 Chapter 2 Section 3 Chemistry of Cells Fats

75 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

76 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Lipids In a __________ 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.

77 Saturated and Unsaturated Fatty Acids
Chapter 2 Section 3 Chemistry of Cells Saturated and Unsaturated Fatty Acids

78 Chapter 2 Section 3 Chemistry of Cells Fatty Acids

79 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

80 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Proteins A protein is a large molecule formed by linked smaller molecules called _____ acids. Amino acids are the building blocks of ________. Twenty different amino acids are found in proteins.

81 Chapter 2 Section 3 Chemistry of Cells Structure of Proteins

82 Chapter 2 Section 3 Chemistry of Cells Proteins

83 Chapter 2 Section 3 Chemistry of Cells Amino Acids

84 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

85 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued Nucleic Acids A nucleic acid is a long chain of smaller molecules called ___________. A nucleotide has three parts: a sugar, a base, and a phosphate group, which contains phosphorus and oxygen atoms.

86 Chapter 2 Section 3 Chemistry of Cells Nucleic Acid

87 Chapter 2 Section 3 Chemistry of Cells Nucleotide

88 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

89 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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 __________________ acid, consists of two strands of nucleotides that spiral around each other. RNA, or ribonucleic acid, consists of a single strand of nucleotides.

90 Structure of Nucleic Acids
Chapter 2 Section 3 Chemistry of Cells Structure of Nucleic Acids

91 Chapter 2 Section 3 Chemistry of Cells DNA Overview

92 Ribonucleic Acid (RNA)
Chapter 2 Section 3 Chemistry of Cells Ribonucleic Acid (RNA)

93 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells 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.

94 Carbon Compounds, continued
Chapter 2 Section 3 Chemistry of Cells Carbon Compounds, continued ATP ATP or adenosine triphosphate, is a single nucleotide with two extra ______-storing phosphate groups. When food molecules are broken down inside cells, some of the energy in the molecules is stored temporarily in ATP.

95 Chapter 2 Section 3 Chemistry of Cells Comparing ADP and ATP

96 Section 4 Energy and Chemical Reactions
Chapter 2 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.

97 Energy for Life Processes
Section 4 Energy and Chemical Reactions Chapter 2 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.

98 Energy for Life Processes
Section 4 Energy and Chemical Reactions Chapter 2 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 ______ or released by chemical reactions.

99 Section 4 Energy and Chemical Reactions
Chapter 2 Energy

100 Energy for Life Processes, continued
Section 4 Energy and Chemical Reactions Chapter 2 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.

101 Energy for Life Processes, continued
Section 4 Energy and Chemical Reactions Chapter 2 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. __________ is the term used to describe all of the chemical reactions that occur within an organism.

102 Energy and Chemical Reactions
Section 4 Energy and Chemical Reactions Chapter 2 Energy and Chemical Reactions

103 Energy for Life Processes, continued
Section 4 Energy and Chemical Reactions Chapter 2 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.

104 Energy for Life Processes, continued
Section 4 Energy and Chemical Reactions Chapter 2 Energy for Life Processes, continued Activation Energy The energy needed to _____ 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.

105 Activation Energy and Chemical Reactions
Section 4 Energy and Chemical Reactions Chapter 2 Activation Energy and Chemical Reactions

106 Section 4 Energy and Chemical Reactions
Chapter 2 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.

107 Section 4 Energy and Chemical Reactions
Chapter 2 Enzymes Enzymes are substances that increase the _____ of chemical reactions. Most enzymes are ________. Enzymes are _________, which are substances that reduce the activation energy of a chemical reaction.

108 Chapter 2 Enzymes, continued
Section 4 Energy and Chemical Reactions Chapter 2 Enzymes, continued An enzyme increases the speed of a chemical reaction by reducing the activation energy of the reaction.

109 Chapter 2 Enzymes, continued
Section 4 Energy and Chemical Reactions Chapter 2 Enzymes, continued An enzyme increases the speed of a chemical reaction by _________ the activation energy of the reaction.

110 Section 4 Energy and Chemical Reactions
Chapter 2 Enzyme

111 Chapter 2 Enzymes, continued Enzyme Specificity
Section 4 Energy and Chemical Reactions Chapter 2 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.

112 Chapter 2 Enzymes, continued Enzyme Specificity
Section 4 Energy and Chemical Reactions Chapter 2 Enzymes, continued Enzyme Specificity A substance on which an enzyme acts during a chemical reaction is called a substrate. Enzymes act only on ________ 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.

113 Chapter 2 Enzymes, continued Enzyme Specificity
Section 4 Energy and Chemical Reactions Chapter 2 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.

114 Chapter 2 Enzymes, continued Enzyme Specificity
Section 4 Energy and Chemical Reactions Chapter 2 Enzymes, continued Enzyme Specificity An enzyme acts only on a specific substrate because only that substrate ____ 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.

115 Section 4 Energy and Chemical Reactions
Chapter 2 Enzyme Activity

116 Chapter 2 Enzymes, continued Factors in Enzyme Activity
Section 4 Energy and Chemical Reactions Chapter 2 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.

117 Chapter 2 Enzymes, continued Factors in Enzyme Activity
Section 4 Energy and Chemical Reactions Chapter 2 Enzymes, continued Factors in Enzyme Activity Any factor that changes the shape of an enzyme can affect the enzyme’s activity. ____________ 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.

118 Factors Affecting Reaction Rate
Section 4 Energy and Chemical Reactions Chapter 2 Factors Affecting Reaction Rate

119 Chapter 2 Multiple Choice
Standardized Test Prep Multiple Choice Use the figure below to answer questions 1–3.

120 Multiple Choice, continued
Chapter 2 Standardized Test Prep Multiple Choice, continued 1. The molecule shown in the diagram is A. cellulose B. DNA C. RNA D. ATP

121 Multiple Choice, continued
Chapter 2 Standardized Test Prep Multiple Choice, continued 1. The molecule shown in the diagram is A. cellulose B. DNA C. RNA D. ATP

122 Multiple Choice, continued
Chapter 2 Standardized Test Prep 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

123 Multiple Choice, continued
Chapter 2 Standardized Test Prep 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

124 Multiple Choice, continued
Chapter 2 Standardized Test Prep 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

125 Multiple Choice, continued
Chapter 2 Standardized Test Prep 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


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