Aerobic Cellular Respiration

• Carbon dioxide, water, and ATP are products of aerobic cellular respiration.
• ATP is used as an energy carrier molecule for powering cell activities.
• Cells use ATP to facilitate tasks like active transport and muscle contractions.
• 34 molecules of ATP are required.
• Aerobic cellular respiration produces about 2 ATP molecules for each glucose molecule.
• The chemical equation for aerobic cellular respiration is: Glucose + Oxygen -> Carbon Dioxide + Water + ATP

Coenzymes in Aerobic Cellular Respiration

• NAD+ (nicotinamide adenine dinucleotide) and FAD (flavin adenine dinucleotide) are coenzymes used in Aerobic Cellular Respiration.
• Coenzymes act as electron carriers, accepting and transferring hydrogen atoms through glycolysis and the Krebs cycle
• When coenzymes gain hydrogen and electrons they become NADH and FADH2

The 4 Major Steps of Aerobic Cellular Respiration

• Glycolysis is the first step.
• Pyruvate Oxidation is the second step.
• The Krebs Cycle is the third step.
• The Electron Transport Chain is the fourth step.

Step 1: Glycolysis

• Glycolysis occurs in the cytosol of cells.
• Glucose molecules are broken down during glycolysis.
• Reactants: 1 molecule of glucose, 2 ATP, and NADH
• Products: 2 Pyruvate, 2 ATP, and 2 NADH

Step 2: Pyruvate Oxidation

• Occurs in the mitochondrial matrix in eukaryotic cells.
• Pyruvate is converted into Acetyl CoA.
• Carbon dioxide is released as waste and diffuses out of the cell.
• The pyruvate oxidation reactants for each glucose molecule include 2 molecules of pyruvate, 2 molecules of NAD+, and 2 molecules of coenzyme.
• The pyruvate oxidation products are 2 molecules of acetyl-CoA, 2 molecules of carbon dioxide, and 2 molecules of NADH.

Step 3: The Krebs Cycle

• A two-carbon unit of acetyl-CoA is combined with a four-carbon molecule (oxaloacetate) to form a six-carbon citrate at the cycle's start.
• Carbon dioxide, NADH, FADH2, and one molecule of ATP are produced.
• The cycle runs twice for every glucose molecule.
• Reactants for each glucose molecule: 2 molecules of acetyl CoA.
• The products are: 4 carbon dioxide, 2 ATP, 6 NADH and 2 FADH2.

Review of Glycolysis, Pyruvate Oxidation, and the Krebs Cycle

• Glycolysis occurs in the cytoplasm, produces 2 ATP per glucose molecule, and 2 NADH.
• Pyruvate Oxidation happens in the mitochondrial matrix, producing 2 NADH
• The Krebs Cycle happens in the mitochondrial matrix, producing 2 ATP, 6 NADH, and 2 FADH2

Step 4: Electron Transport Chain

• The electron transport chain occurs within the inner membrane of mitochondria in eukaryotic cells.
• NADH and FADH2 donate their electrons to the electron transport chain, producing ATP.
• Molecular oxygen acts as the final electron acceptor.
• Oxygen combines with hydrogens to form water
• As hydrogen moves through ATP synthase, it moves down its concentration gradient and converts ADP to ATP.
• NADH, FADH2, and oxygen are the electron transport system reactants.
• NAD+, FAD, water and ATP are the electron transport system products.
• Glycolysis is the first process in breaking down glucose.
• Pyruvate oxidation, the Krebs cycle, and the electron transport chain occur in the mitochondria.
• Pyruvate oxidation transforms pyruvates into acetyl and carbon dioxide.
• The Krebs cycle produces both NADH and FADH2.
• The electron transport system requires oxygen and turns it into water.
• Carbon dioxide is produced from breaking down food molecules in aerobic cellular respiration.
• Oxygen does not turn into carbon dioxide.

Fermentation

• Fermentation lets glycolysis produce small amounts of ATP without oxygen.
• Fermentation and aerobic respiration both produce energy (ATP) from glucose breakdown
• Fermentation produces two ATP molecules.
• Alcohol and lactate fermentation are types of fermentation
• Beer is made with alcohol fermentation, while yogurt is made with lactate fermentation.