Biology 11

Cellular Respiration  Occurs in every cell in your body  Converts glucose to ATP (Adenosine triphosphate)  ATP =Energy currency for most cellular processes

Respiration does NOT equal breathing  Cellular Respiration is NOT the same as breathing Breathing is the movement of gases between the respiratory membrane of living things and their external environment Respiration is the process to supply oxygen to the cells of the body

The whole process  Glucose + Oxygen  Carbon Dioxide + Water + ATP (energy)  C 6 H 10 O O 2  6CO H 2 O + 36 ATP

Aerobic - four steps  Glycolysis Splitting of sugars  Transition Reaction Prepared for further reactions  Krebs Cycle (Citric Acid Cycle) Electron Carrier molecules are loaded  Electron Transport System Transforms stored energy in electron carrier molecules into ATP energy

Step #1 - Glycolysis  Location: Cytoplasm of cell  Literally means “Splitting of Sugars”  One molecule of glucose (C 6 H 10 O 6 ) is broken down into two molecules of pyruvate.

Step #1 - Glycolysis  Two phases: Phase 1: Preparatory Phase ○ Costs 2 ATP Phase 2: Payoff Phase ○ Produces 4 ATP ○ Produces 2 NADH  Glycolysis produces 2 ATP and 2 NADH

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Step #2 – Transition Reaction  Pyruvate is taken into the mitochondria  Carbon Dioxide is lost  Pyruvate attaches to Coenzyme-A to form Acetyl-CoA

Step #3 – The Krebs Cycle  Location: The Mitochondrial Matrix (the jelly part of the mitochondria )  Oxygen strips Hydrogen from Acetyl Co-A, two at a time. This provides the electrons for the next step  Results in 4 ATP and lots of NADH and FADH 2  At the end of the Krebs Cycle, all six carbon from the original glucose molecule have been lost in the form of CO 2

Step #4 – The Electron Transport Chain  Location: In the Mitochondria  Purpose: To convert the energy stored in NADH and FADH 2 to ATP  ~ 32 ATP are produced

Step #4-The Electron Transport Chain  Like moving down a set of stairs, releasing more and more energy  Oxygen is needed for the Electron Transport Chain to function. It is the final electron acceptor for aerobic respiration It combines with Hydrogen to form water

Overview: Glycolysis Transiton Reaction Krebs Cycle Electron Transport Chain Reactants [What goes in] Glucose2 Pyruvate Coenzyme A 2 Acetyl Co-A Oxygen NADH FADH 2 Products [What comes out] 2 Pyruvate 2 NADH Acetyl Co-A CO 2 NADH FADH 2 CO 2 H 2 O # ATP produced 204~32 Location of reaction in cell CytoplasmCytoplasm to Mitochondrial Matrix Mitochondrial Matrix Mitrochondrial Christae

The Overall Purpose  To Convert Glucose to an energy form that can be used by our cells: ATP

Anaerobic Respiration  Cellular Respiration in the Absence of Oxygen  Two major types: Lactic Acid Fermentation Alcoholic Fermentation

Lactic Acid Fermentation  Takes place in hard working muscle cells  A form of glycolysis breaks down glucose into lactic acid  Lactic Acid accumulates during strenuous exercise if sufficient energy is not available.  Produces a net of only 2 ATP From glycolysis

Alcoholic Fermentation  Location: cytoplasm of yeast cells  Glucose is broken down to alcohol and CO 2  93% of energy from glucose is stored in bonds of alcohol This is why alcohol is so flammable.