Cellular Respiration Review
• Occurs in all eukaryotes• Generates ATP• Involves oxidation – reduction reactions
– Oxidation = loss of electron / H atom; Reduction = gain of electron / H atom;
Glycolosis
• Takes place in cytoplasm• Starts with glucose• NET YIELD: 2 NADH (goes
to ETC) and 2 ATP
The Prepatory Step & the Krebs Cycle
• Takes place in mitochondrial matrix
• Uses Coenzyme A to prepare pyruvate
• Completes breakdown of glucose to CO2
• Each molecule of pyruvate processed generates– 4 NADH– 1 FADH2
– 1 ATP
Electron Transfer Chain
• ETC: Occurs across inner mitochondrial membrane
• Electrons from NADH and FADH2 move down ETC
• O2 is the final oxygen acceptor
• Generates a H+ gradient
• H+ gradient powers ATP Synthase enzyme to phosphorylate ADP to ATP (Chemiosmosis)ADP + P ATP
• ETC Yield = 32-34 ATP molecules
Electron Transfer Chain
What if there’s no Oxygen?
• O2 can’t act as final electron acceptor
• ETC can’t happen• Can still get 2 ATP from and 2 NADH glycolysis
(doesn’t require O2)
What if there’s no Oxygen?
PRESENCE OF O2
• NADH goes to ETC
ABSENCE OF O2
•ETC can’t function•NADH must be oxidized back to NAD+
Anaerobic Respiration
• Respiration in the absence of oxygen• Oxidizes NADH to replenish NAD+
• Lactic Acid Fermentation• Alcohol Fermentation
Anaerobic Respiration
LACTIC ACID FERMENTATION
• Occurs in muscle cells• Oxidizes NADH to NAD+ by reducing pyruvate to lactate
(lactic acid)
Anaerobic Respiration
AlCOHOLIC FERMENTATION• Occurs in yeast• Oxidizes NADH to NAD+ by reducing pyruvate to ethanol
(ethyl alcohol)
Why we like fermentation
Often used by bacteria to make tasty foods
• Used for thousands of years• A method of preserving
food
Other Organic Molecules as Fuel for Cellular Respiration
Carbohydrates: Enter at beginning of glycolysis•Examples: Starch, Glycogen
Other Organic Molecules as Fuel for Cellular Respiration
Fats: Glycerol enters glycolysisFatty Acids broken into 2-C pieces and sent to Citric Acid Cycle
1 g fat yields 2x ATP as 1g starch
Other Organic Molecules as Fuel for Cellular Respiration
Proteins: broken into amino acids Can enter respiration at many points