Cellular Respiration Chapter 9

Chemical Energy and Food Living things get the energy they need from food. The process of releasing the energy stored in food is cellular respiration.

Overview of Cellular Respiration In the presence of oxygen, aerobic respiration takes place. This produces 36 ATP per molecule of glucose. In the absence of oxygen, anaerobic respiration (fermentation) takes place. This produces 2 ATP per molecule of glucose.

Fermentation (without oxygen) Section 9-1 Chemical Pathways Glucose Krebs cycle Electron transport Glycolysis Alcohol or lactic acid Fermentation (without oxygen)

Glycolysis Both aerobic and anaerobic respiration begin with a process known as glycolysis. This means “glucose -splitting” This takes place in the cytoplasm.

To the electron transport chain Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain

To the electron transport chain Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain

To the electron transport chain Glycolysis Section 9-1 Glucose 2 Pyruvic acid To the electron transport chain

Glycolysis If oxygen is available, the pyruvic acid molecules will be broken down further to release more energy. If oxygen is unavailable, the pyruvic acid molecules will be converted to a waste product with no further release of energy (fermentation).

Fermentation (without oxygen) Section 9-1 Chemical Pathways Glucose Krebs cycle Electron transport Glycolysis Alcohol or lactic acid Fermentation (without oxygen)

Fermentation Also known as anaerobic respiration. Two types: Alcoholic fermentation – in yeasts Pyruvic acid is converted to alcohol and carbon dioxide. Lactic acid fermentation – in bacteria and muscle cells Pyruvic acid is converted to lactic acid.

Lactic Acid Fermentation Section 9-1 Lactic acid Glucose Pyruvic acid

Aerobic Respiration 6O2 + C6H12O6  6CO2 + 6H2O + 36 ATP Oxygen + glucose  carbon dioxide + water + energy

Mitochondrial Reactions Mitochondrion Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Electron Transport Chain Krebs Cycle Glycolysis Mitochondrion Cytoplasm

Flowchart Aerobic Cellular Respiration Glucose (C6H1206) + Oxygen (02) Section 9-2 Flowchart Aerobic Cellular Respiration Glucose (C6H1206) + Oxygen (02) Glycolysis Krebs Cycle Electron Transport Chain Carbon Dioxide (CO2) + Water (H2O)

Aerobic Respiration In the presence of oxygen, pyruvic acid is further broken down to release additional energy. This takes place in the mitochondria. There are two steps: The Krebs Cycle The electron transport chain

The Krebs Cycle Also known as the citric acid cycle. Pyruvic acid (from glycolysis) is broken down into carbon dioxide. High energy electrons are captured by NAD and FAD and brought to the electron transport chain. Net gain of 2 ATP from this cycle.

The Krebs Cycle Section 9-2 Citric Acid Production Mitochondrion

Electron Transport Chain NADH and FADH2 drop off high energy electrons. These pass through a series of reactions located on the inner membrane that produce ATP. Oxygen combines with hydrogen to make water. Net gain of ATP = 32

Electron Transport Chain Section 9-2 Electron Transport Hydrogen Ion Movement Channel Mitochondrion Intermembrane Space ATP synthase Inner Membrane Matrix ATP Production

ATP totals Glycolysis – 2 Krebs Cycle – 2 Electron Transport Chain – 32 Net: from one glucose molecule = 36 ATP

Photosynthesis & Cellular Respiration Function Energy capture Energy release Location Chloroplasts Mitochondria Reactants CO2 & H2O C6H12O6 & O2 Products CO2 and H2O Equation 6CO2 + 6H2O  C6H12O6 + 6O2 6O2 + C6H12O6  6CO2 + 6H2O