oxygen+ glucose carbon dioxide+ water +energy Cellular Respiration oxygen+ glucose carbon dioxide+ water +energy 6O2 + C6H12O6  6CO2 + 6H2O +ATP

Cellular Respiration Since animals cannot create food they eat plants, or they eat plant-eating animals. Plants and animals get energy from food by cellular respiration. Occurs in the mitochondria, of the cell. Oxygen is used to get the energy out of sugar.

Cellular Respiration How much energy is actually in food? 1 gram of the sugar glucose, when burned in the presence of oxygen, releases 3811 calories of heat energy!!!! What is a calorie? The amount of energy needed to raise the temp of one gram of water 1 degree Celcius.

Cellular Respiration Cells, of course don’t burn glucose, instead they gradually release energy from glucose and other food compounds. Release of energy from glucose occurs in 3 steps The pathway begins with Glycolysis The Krebs Cycle And the Electron Transport Chain

Glycolysis Occurs in the cytoplasm of the cell. Glycolysis is the process in which one molecule of glucose(6C) is broken in half, producing two molecules of pyruvic acid(3C) Requires 2 ATP molecules to get it started but produces 4 ATP molecules and 2 NADH molecules in return

The cell has a net gain of 2 ATP Glycolysis The cell has a net gain of 2 ATP

Fermentation When Oxygen is not present, glycolysis is followed by a different pathway. Fermentation. Alcoholic Fermentation – Produces Ethyl Alcohol and Carbon dioxide Bread, beer, and wine are produced

Fermentation Lactic Acid Fermentation Produced in your muscles during rapid exercise when the body cannot supply enough oxygen to the tissues. This is why muscles feel sore after intense activity Produces Lactic Acid and NAD+

Without Oxygen= Anaerobic Fermentation Without Oxygen= Anaerobic

Overview of Cellular Respiration Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Glycolysis Cytoplasm Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place inside the mitochondria. Mitochondrion Copyright Pearson Prentice Hall

Cellular Respiration

Krebs Cycle Also called the citric acid cycle Occurs after glycolysis Aerobic respiration (with oxygen) Occurs in the mitochondria During the Krebs Cycle, pyruvic acid is broken down into carbon dioxide, NADH, ATP, and FADH2 in a series of energy extracting reactions. 2

Krebs Cycle Steps: In the presence of oxygen, pyruvic acid produced in glycolysis passes to the 2nd stage of cellular respiration. During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. Pyruvic Acid enters the mitochondrion, eventually forming citric acid. Citric acid is broken down to form a 4-carbon molecule and carbon dioxide. FADH2 and NADH are formed.

Figure 9-6 The Krebs Cycle

Chemical Pathways Glucose Glycolysis Electron Transport Krebs Cycle Fermentation (without 0xygen) Alcohol or lactic acid

Electron Transport Chain Uses high-energy electrons from the Krebs cycle to convert ADP into ATP. High-energy electrons from NADH and FADH2 are passed into and along the electron transport chain. As H is released to form NAD and FAD, ATP is formed. A TOTAL of 38 ATP are formed but 2ATP are used in Glycolysis leaving a net of 36 ATP.

Figure 9–7 Electron Transport Chain Mitochondrion Electron Transport Hydrogen Ion Movement Channel Intermembrane Space ATP synthase Inner Membrane Matrix ATP Production Go to Section:

Total energy produced by aerobic respiration = 36 ATP

Comparing Photosynthesis and Cellular Respiration Function Energy storage Energy release Location Chloroplasts Mitochondria Reactants CO2 and H2O C6 H12O6 and O2 Products C6H12O6 and O2 Equation 6CO2 +6H2O -> Glucose + 6O2 6O2 + Glucose -> 6CO2 + 6H2O