Cellular Respiration  A quick review…  When we eat, we get energy (glucose and other sugars)  Food energy is broken down into usable energy  Energy used to bond phosphate groups to ADP to make ATP ADP – P ATP

Cellular Respiration  What is cell respiration???  Respiration: the process of breaking down food molecules and changing these into usable energy - ATP  THE GOAL:  Create ATP for cells to use  Free up electrons—have high energy

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Cellular Respiration

 Types of cell respiration  Aerobic Processes:  REQUIRE oxygen to take place  A lot of energy available (efficient)  Anaerobic Processes:  DO NOT require oxygen to take place  Get energy quickly (inefficient)

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Glycolysis  Involves breaking down 6-carbon sugars  Break sugars into pyruvic acid molecules  3-Carbon molecules  This process is ANAEROBIC  No oxygen necessary  Occurs in the cytoplasm of cells

Glycolysis

 Glycolysis also creates hydrogen ions and free electrons  The whole point of respiration = high energy  H + ions bond with NAD + to form NADH + H +  NADH carries electrons and H + ions  This process uses 4 ADP molecule and creates 4 ATP molecules

Glycolysis

 TOTAL ATP PRODUCTION:  Glycolysis Step 1 uses 2 ATP molecules  Glycolysis Step 2 converts 4 ADP molecules into 4 ATP molecules  Net ATP production = 2 ATP for every glucose molecule

Glycolysis  When oxygen is present, aerobic respiration occurs  Happens in the mitochondria

Glycolysis  Breaking down Pyruvic Acid…  Occurs in the mitochondria  Pyruvic Acid = 3-carbon compound  Broken down into…  2-Carbon compound—acetic acid  Carbon Dioxide

Glycolysis  Intermediate Step in Glycolysis  2-Carbon Compound—Acetic Acid  Combined with coenzyme A (CoA)  Forms compound called acetyl-CoA  This is only an intermediate step—have to move pyruvic acid into Krebs Cycle

Glycolysis Glycolysis = 2 ATP

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Citric Acid (Krebs) Cycle  Produces more ATP and releases more electrons  Electrons picked up by NAD + and FAD  Organic carrier molecules  Occurs inside mitochondria  Mitochondrial Matrix

Citric Acid (Krebs) Cycle  Acetyl CoA combines with a 4-carbon molecule to form a 6-carbon molecule  Citric Acid  Citric Acid broken down into a 5-carbon compound  NAD + removes electrons (NADH + H + )  CO 2 released

Citric Acid (Krebs) Cycle  5-carbon compound broken down into a 4-carbon compound  ATP created  NAD + removes electrons (NADH + H + )  CO 2 released  4-carbon compound (oxaloacetic acid) is created  Used to bond with acetyl- CoA to restart cycle

Citric Acid (Krebs) Cycle

Citric Acid Cycle = 2 ATP Citric Acid (Krebs) Cycle

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Electron Transport Chain  What is the ETC ?  A series of molecules along which electrons are transferred, releasing energy  Occurs in the mitochondria— wall of mitochondria  Aerobic process  Oxygen is involved Acts as the electron acceptor

Electron Transport Chain  As the electrons are passed between carrier proteins, energy is released  ATP is created  Electrons are given up by the carrier molecules  NADH and FADH NAD + and FAD

Electron Transport Chain

 As the electrons (H + ions) travel down the chain, they bond with oxygen  2 H O = water (H 2 O)  Electron acceptor  Carbon is given off as carbon dioxide

Electron Transport Chain

Glycolysis ETC = 34 ATP

Electron Transport Chain  A problem exists if there is no oxygen  Anaerobic process  When oxygen is used up, electrons cannot be removed  Traffic jam in the mitochondria  KEY POINT —Electron Transport Chain cannot run without oxygen

Anaerobic Respiration  If no oxygen present after glycolysis, pyruvic acid can still be broken down  Fermentation No ATP made during fermentation  Uses electrons carried by NADH + H + so that NAD + can regenerate for glycolysis

Anaerobic Respiration

 Two types of fermentation  Lactic Acid Fermentation  Alcoholic Fermentation Glucose 2 Pyruvic Acid 2 Lactic Acid Glucose 2 Pyruvic Acid 2 Ethanol + 2 CO 2

Anaerobic Respiration  Lactic Acid Fermentation  Muscle fatigue  When your muscle cells require more energy than can be produced  Lack of oxygen  Lactic acid build up = muscle fatigue  When oxygen is present, lactic acid breaks down

Anaerobic Respiration

 Alcohol Fermentation  Occurs in bacteria, plants and most animals  Can you think of a bacteria that is used for fermentation???  Pyruvic Acid is converted into ethanol and carbon dioxide

Anaerobic Respiration

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Cellular Respiration General Formula C 6 H 12 O O 2 6 CO H 2 O