KEY CONCEPT All cells need chemical energy.

4.1 Chemical Energy & ATP KEY CONCEPT All cells need chemical energy.

4.1 Chemical Energy & ATP Starch molecule Glucose molecule The chemical energy used for most cell processes is carried by ATP. • Molecules in food store chemical energy in their bonds.

4.1 Chemical Energy & ATP phosphate removed • ATP transfers energy from the breakdown of food molecules to cell functions. • Energy is released when a phosphate group is removed. • ADP is changed into ATP when a phosphate group is added.

4.1 Chemical Energy & ATP adenosine triphosphate tri=3 adenosine diphosphate di=2 Organisms break down carbon-based molecules to produce ATP. • Carbohydrates are the molecules most commonly broken down to make ATP. • not stored in large amounts • up to 36 ATP from one glucose molecule

4.1 Chemical Energy & ATP • Fats store the most energy. • 80 percent of the energy in your body • about 146 ATP from a triglyceride • Proteins are least likely to be broken down to make ATP. • amino acids not usually needed for energy • about the same amount of energy as a carbohydrate

4.1 Chemical Energy & ATP A few types of organisms do not need sunlight and photosynthesis as a source of energy. • Some organisms live in places that never get sunlight. • In chemosynthesis, chemical energy is used to build carbon-based molecules. • similar to photosynthesis • uses chemical energy instead of light energy

4.2 Overview of Photosynthesis KEY CONCEPTThe overall process of photosynthesis produces sugars that store chemical energy.

4.2 Overview of Photosynthesis Photosynthetic organisms are producers. • Producers make their own source of chemical energy. • Plants use photosynthesis and are producers. • Photosynthesis captures energy from sunlight to make sugars.

4.2 Overview of Photosynthesis chloroplast leaf cell leaf • Chlorophyll is a molecule that absorbs light energy. • In plants, chlorophyll is found in organelles called chloroplasts.

4.2 Overview of Photosynthesis grana (thylakoids) chloroplast stroma Photosynthesis in plants occurs in chloroplasts. • Photosynthesis takes place in two parts of chloroplasts. • grana (thylakoids) • stroma

4.2 Overview of Photosynthesis • The light-dependent reactions capture energy from sunlight. • take place in thylakoids • water and sunlight are needed • chlorophyll absorbs energy • energy is transferred along thylakoid membrane then to light-independent reactions • oxygen is released

4.2 Overview of Photosynthesis • The light-independent reactions make sugars. • take place in stroma • needs carbon dioxide from atmosphere • use energy to build a sugar in a cycle of chemical reactions

4.2 Overview of Photosynthesis granum (stack of thylakoids) 1 chloroplast sunlight 6H2O 6O2 2 energy thylakoid stroma (fluid outside the thylakoids) 6CO2 1 six-carbon sugar C6H12O6 3 4 • The equation for the overall process is: 6CO2 + 6H2O  C6H12O6 + 6O2

4.3 Photosynthesis in Detail KEY CONCEPT Photosynthesis requires a series of chemical reactions.

4.3 Photosynthesis in Detail The first stage of photosynthesis captures and transfers energy. • The light-dependent reactions include groups of molecules called photosystems.

4.3 Photosynthesis in Detail • Photosystem II captures and transfers energy. • chlorophyll absorbs energy from sunlight • energized electrons enter electron transport chain • water molecules are split • oxygen is released as waste • hydrogen ions are transported across thylakoid membrane

4.3 Photosynthesis in Detail • Photosystem I captures energy and produces energy-carrying molecules. • chlorophyll absorbs energy from sunlight • energized electrons are used to make NADPH • NADPH is transferred to light-independent reactions

4.3 Photosynthesis in Detail • The light-dependent reactions produce ATP. • hydrogen ions flow through a channel in the thylakoid membrane • ATP synthase attached to the channel makes ATP

4.3 Photosynthesis in Detail The second stage of photosynthesis uses energy from the first stage to make sugars. • Light-independent reactions occur in the stroma and use CO2 molecules.

4.3 Photosynthesis in Detail • A molecule of glucose is formed as it stores some of the energy captured from sunlight. • carbon dioxide molecules enter the Calvin cycle • energy is added and carbon molecules are rearranged • a high-energy three-carbon molecule leaves the cycle

4.3 Photosynthesis in Detail • A molecule of glucose is formed as it stores some of the energy captured from sunlight. • two three-carbon molecules bond to form a sugar • remaining molecules stay in the cycle

4.4 An Overview of Cellular Respiration KEY CONCEPT The overall process of cellular respiration converts sugar into ATP using oxygen.

4.4 An Overview of Cellular Respiration mitochondrion animal cell Cellular respiration makes ATP by breaking down sugars. • Cellular respiration is aerobic, or requires oxygen. • Aerobic stages take place in mitochondria.

4.4 An Overview of Cellular Respiration • Glycolysis must take place first. • anaerobic process (does not require oxygen) • takes place in cytoplasm • splits glucose into two three-carbon molecules • produces two ATP molecules

4.4 An Overview of Cellular Respiration 1 ATP mitochondrion matrix (area enclosed by inner membrane) and 6CO 2 energy 2 3 energy from glycolysis ATP inner membrane and and 6H O 6O 2 2 4 Cellular respiration is like a mirror image of photosynthesis. • The Krebs cycle transfers energy to an electron transport chain. • takes place inmitochondrial matrix • breaks down three-carbonmolecules from glycolysis Krebs Cycle • makes a small amount of ATP • releases carbon dioxide • transfers energy-carrying molecules

4.4 An Overview of Cellular Respiration 1 ATP mitochondrion matrix (area enclosed by inner membrane) and 6CO 2 energy 2 Electron Transport 3 energy from glycolysis ATP inner membrane and and 6H O 6O 2 2 4 • The electron transport chain produces a large amount of ATP. • takes place in inner membrane • energy transferred to electron transport chain • oxygen enters process • ATP produced • water released as awaste product

4.4 An Overview of Cellular Respiration • The equation for the overall process is: C6H12O6 + 6O2  6CO2 + 6H2O • The reactants in photosynthesis are the same as the products of cellular respiration.

4.5 Cellular Respiration in Detail KEY CONCEPT Cellular respiration is an aerobic process with two main stages.

4.5 Cellular Respiration in Detail Glycolysis is needed for cellular respiration. • The products of glycolysis enter cellular respiration when oxygen is available. • two ATP molecules are used to split glucose • four ATP molecules are produced • two molecules of NADH produced • two molecules of pyruvate produced

4.5 Cellular Respiration in Detail The Krebs cycle is the first main part of cellular respiration. • Pyruvate is broken down before the Krebs cycle. • carbon dioxide released • NADH produced • coenzyme A (CoA) bonds to two-carbon molecule

4.5 Cellular Respiration in Detail • The Krebs cycle produces energy-carrying molecules.

4.5 Cellular Respiration in Detail • The Krebs cycle produces energy-carrying molecules. • NADH and FADH2 are made • intermediate molecule withCoA enters Krebs cycle • citric acid(six-carbon molecule)is formed • citric acid is broken down,carbon dioxide is released,and NADH is made • five-carbon molecule is broken down, carbon dioxide is released, NADH and ATP are made • four-carbon molecule is rearranged

4.5 Cellular Respiration in Detail The electron transport chain is the second main part of cellular respiration. • The electron transport chain uses NADH and FADH2 to make ATP. • high-energy electrons enter electron transport chain • energy is used to transport hydrogen ions across the inner membrane • hydrogen ionsflow through achannel in themembrane

4.5 Cellular Respiration in Detail The electron transport chain is the second main part of cellular respiration. • The breakdown of one glucose molecule produces up to38 molecules of ATP. • The electron transport chain uses NADH and FADH2 to make ATP. • ATP synthase produces ATP • oxygen picks up electrons and hydrogen ions • water is released as a waste product

4.6 Fermentation KEY CONCEPT Fermentation allows the production of a small amount of ATP without oxygen.

4.6 Fermentation Fermentation allows glycolysis to continue. • Fermentation allows glycolysis to continue making ATP when oxygen is unavailable. • Fermentation is an anaerobic process. • occurs when oxygen is not available for cellular respiration • does not produce ATP

4.6 Fermentation • Fermentation allows glycolysis to continue making ATP when oxygen is unavailable. • NAD+ is recycled to glycolysis • Lactic acid fermentation occurs in muscle cells. • glycolysis splits glucose into two pyruvate molecules • pyruvate and NADH enter fermentation • energy from NADH converts pyruvate into lactic acid • NADH is changed back into NAD+

4.6 Fermentation Fermentation and its products are important in several ways. • Alcoholic fermentation is similar to lactic acid fermentation. • glycolysis splits glucose and the products enter fermentation • energy from NADH is used to split pyruvate into an alcohol and carbon dioxide • NADH is changed back into NAD+ • NAD+ is recycled to glycolysis

4.6 Fermentation • Fermentation is used in food production. • yogurt • cheese • bread

KEY CONCEPT All cells need chemical energy.