Chapter 9 Cellular Respiration Fermentation ATP Energy I

Chapter 9: Cellular Respiration & Fermentation

ATP & Energy I. Structure of ATP A. ATP (Adenosine Triphosphate) – shuttles energy for cells B. ATP is composed of ribose (a sugar), adenine (a nitrogenous base), and three phosphate groups

II. ATP & Energy A. The bond between the terminal phosphate groups of ATP’s can be broken, releasing organic phosphate and leaving ADP (adenosine diphosphate). B. Energy is released from ATP when the terminal phosphate bond is broken. C. This release of energy comes from the chemical change to a state of lower free energy (stabilizing), not from the phosphate bonds themselves.

Glycolysis & Fermentation I. Harvesting Chemical Energy A. Cellular Respiration – the break down of organic compounds (food, glucose, etc. ) in cells to make energy, ATP molecules C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O + Energy

B. Glycolsysis 1. Biochemical pathway that always starts cellular respiration!!! 2. Does produce a small amount of ATP. 3. Other products can follow two other pathways, depending on whether oxygen is present not.

ATP Glycolysis Oxygen Absent Fermentation (anaerobic) Oxygen Present Aerobic Respiration ATP

C. Two (2) Types of Cellular Respiration 1. Anaerobic Respiration – respiration without oxygen – Also called fermentation 2. Aerobic Respiration – respiration with oxygen

II. Glycolysis A. Basics of Glycolysis 1. glyco: sugar lysis: break up • Begins to break down glucose & releases a small amount of energy (ATP) 2. Occurs in the cytoplasm. 3. All types of cellular respiration begin with glycolysis!!!!!

B. Major events in Glycolysis 1. Start with (invest) 1 glucose, 2 NAD+, and 2 ATP molecules. 2. Glucose, a 6 -carbon molecule, is split into 2 PGAL, or glyceraldehyde-3 -phosphate, molecules (each a 3 -carbon molecule). 3. Hydrogens are transferred from the 2 PGAL molecules to the 2 NAD+ molecules. This produces 2 NADH molecules. 4. 4 ATP molecules are then produced (2 ATP overall). This also produces 2 pyruvic acid molecules. 5. Ends with 2 pyruvic acid, 2 ATP, 2 NADH molecules.

Glycolysis

III. Anaerobic Respiration A. Basics 1. Also known as Fermentation 2. Does not make any ATP! 3. Does remake NAD+, which goes back through Glycolysis to make 2 more ATP.

B. 2 Types of Fermentation 1. Lactic Acid Fermentation • 2 H+ are removed from 2 NADH to make NAD+. • Pyruvic acid is converted into lactic acid by gaining the 2 H+. • NAD+ goes back through glycolysis to make more ATP.

Figure 9. 17 b 2 ADP 2 P i Glucose 2 ATP Glycolysis 2 NAD 2 Lactate (b) Lactic acid fermentation 2 NADH 2 Pyruvate

2. Alcoholic Fermentation • A CO 2 molecule is removed from each pyruvic acid, creating acetaldehyde. • 2 H+ are removed from 2 NADH to make NAD+. • Acetaldehyde is converted into ethyl alcohol by gaining the 2 H+. • NAD+ goes back through glycolysis to make more ATP.

Figure 9. 17 a 2 ADP 2 P i Glucose 2 ATP Glycolysis 2 Pyruvate 2 NAD 2 Ethanol (a) Alcohol fermentation 2 NADH 2 CO 2 2 Acetaldehyde

IV. Mitochondria Review A. Structure 1. Surrounded by a double membrane 2. The 2 nd, inner membrane, is highly folded to increase surface area. Each fold is called a cristae 3. The very interior of the mitochondria is called the mitochondrial matrix.

IV. Aerobic Respiration A. Basics 1. Aerobic Respiration requires oxygen (O 2)! 2. Produces nearly 20 times more ATP than glycolysis alone. 3. Begins with Glycolysis, followed by the Kreb’s Cycle, the Electron Transport Chain, and Chemiosmosis.

B. Glycolysis 1. Converts glucose into 2 pyruvic acids. 2. Makes 2 NADH and a net of 2 ATP. 3. Occurs in the cytoplasm C. Pyruvic acid is converted into Acetyl Co. A. 1. The 2 Pyruvic Acids pass through both mitochondrial membranes into the mitochondrial matrix. 2. As this happens, the 2 pyruvic acids reacts with a molecule called coenzyme A to form Acetyl Co. A. 3. 2 NADH’s and CO 2 are produced.

D. Kreb’s Cycle 1. Each Acetyl Co. A is broken down to make 1 ATP, 3 NADH, and 1 FADH 2. 2. 1 st product is remade in the last step, so the Kreb’s Cycle can happen again. 3. Remember, there are 2 Acetyl Co. A’s, so the Kreb’s cycle will happen twice. 4. Our totals are therefore: 2 ATP, 6 NADH, and 2 FADH 2.

Acetyl Co. A-SH NADH H 2 O 1 + H NAD 8 Oxaloacetate 2 Malate Citrate Isocitrate NAD H 2 O Citric acid cycle 7 Fumarate NADH 3 + H CO 2 Co. A-SH -Ketoglutarate 6 4 Co. A-SH 5 FADH 2 NAD FAD Succinate GTP GDP ATP Pi Succinyl Co. A NADH + H CO 2

E. Electron Transport Chain 1. Occurs across the inner membrane of the mitochondria (cristae). 2. H+ ions are released from NADH and FADH 2 into the mitochondrial matrix. 3. The electrons in the hydrogen atoms are at a high energy level! 4. The high energy electrons are passed along a series of molecules called the Electron Transport Chain.

E. Electron Transport Chain (cont. ) 5. As the electrons move from molecule to molecule, they lose some of their energy. 6. This energy pumps H+ out of the mitochondrial matrix, into the space between the two mitochondrial membranes. 7. A high concentration of H+ builds up in this space.

Electron Transport Chain

F. Chemiosmosis 1. H+ ions diffuse from the high area of concentration made in between the 2 mitochondrial membranes to the low are in the matrix. 2. Specifically the H+ ions move through a protein called ATP Synthase. 3. As H+ ions move through ATP Synthase, ATP is made! 4. 34 ATP are made in chemiosmosis. 5. The H+ ions then combine with oxygen to form water.

Electron Transport Chain

Summary of Aerobic Respiration Total ATP made aerobically: 38 ATP’s Glycolysis = 2 Kreb’s Cycle = 2 Electron Transport Chain = 34