Cellular Respiration

Mitochondria Many in active cells such as muscle Double membrane (inner and outer) Inner membrane is folded Folds = more surface area

Oxygen determines outcome Aerobic With oxygen Makes more energy Anaerobic Without oxygen Less effective Not sustainable Fermentation

Glucose Monosaccharide carbohydrate Stored in animals as glycogen (starch in plants) During digestion, many compounds are converted to glucose for cell use Source of energy, but not usable by cell organelles, must be converted to ATP

Overview

Steps to respiration Glycolysis Krebs or Citric Acid Cycle Formation of Acetyl CoA Krebs or Citric Acid Cycle Electron Transport Chain (ETC)

Glycolysis Occurs in cytoplasm Break glucose in half  pyruvic acid Uses 2 ATP, releases 4 ATP produced: Net 2 ATP NAD+ (nicotinamide adenine dinucleotide) accepts electrons to become NADH (helps carry energy from glucose to other pathways)

Inside the mitochondria A. Formation of acetyl CoA B. Krebs cycle C. Electron transport chain

A. Formation of Acetyl-CoA Pyruvate is split to form CO2 and acetyl group. Acetyl group attaches to coenzyme A to form acetyl CoA NAD+ takes electrons to make NADH Acetyl CoA to Krebs

B. Kreb’s Cycle/Citric Acid Cycle Acetyl CoA to citric acid Cycle proceeds Total summary: 4 CO2 2 ATP 6 NADH 2 FADH2

C. Electron Transport Chain

ETC Inner membrane of mitochondria High energy electrons from NADH and FADH2 Enzymes at the end combine electrons with hydrogen ions and oxygen to form water (oxygen is final electron acceptor) Electron energy pumps H+ ions in ATP synthase uses gradient to produce ATP

Alternate Pathway: Fermentation Required to turn NADH from glycolysis back to NAD+ to keep process going (normal it goes to ETC) Can keep glycolysis going, but does not fully use energy of glucose and is less efficient than aerobic respiration Lactic acid: pyruvate to lactate (yogurt, sour cream, and cheese! YUM) Alcoholic fermentation: pyruvate to ethanol and CO2, yeast