Glycolysis: Preparatory Phase

• Catabolic reactions release chemical energy from organic molecules.
• Anabolic reactions use energy to build complex molecules.
• Oxidation involves the loss of electrons.
• Reduction involves the gain of electrons.
• NAD+ and FAD are the coenzymes primarily responsible for carrying electrons.
• The reduced forms of NAD/FAD have higher potential energy.
• ATP is constantly broken down for energy in cells.
• Energy is extracted from ATP through the hydrolysis of a phosphate bond.
• The products of ATP hydrolysis are ADP, inorganic phosphate (Pi), and energy.
• The phosphagen system is the fastest way skeletal muscle resynthesizes ATP.
• Substrate-level phosphorylation involves ATP generation directly from a substrate.
• Oxidative phosphorylation occurs in the mitochondrial inner membrane.
• Glucose primarily comes from carbohydrates.
• Glucose contains 6 carbon atoms.
• Glucose is broken down in the glycolysis pathway.
• Glycolysis occurs in the cytoplasm.

Glycolysis: Preparatory Phase

• During the preparatory phase of glycolysis, glucose is phosphorylated and split into two 3-carbon molecules.
• 2 ATP molecules are used in the preparatory phase.
• Rate-limiting enzymes in glycolysis include hexokinase and phosphofructokinase (PFK).
• Glyceraldehyde-3-phosphate (G3P) is formed at the end of the glycolysis preparatory phase.
• G3P contains 3 carbon atoms.

Glycolysis: Production Phase

• The production phase of glycolysis creates ATP and NADH.
• 4 ATP molecules are produced in the glycolysis production phase.
• The net ATP gain from glycolysis is 2 ATP.
• The end products of glycolysis are 2 NADH, 2 ATP, and 2 pyruvate molecules.
• Pyruvate is converted to Acetyl CoA.
• Pyruvate dehydrogenase is the enzyme that converts pyruvate to Acetyl CoA.
• NADH enters the mitochondria using shuttle systems.
• The glycerol-3-phosphate shuttle is used in fast-twitch muscle.
• The malate-aspartate shuttle is used in the liver and slow-twitch muscle.
• Anaerobic glycolysis forms lactate.
• Lactate is formed when pyruvate can't enter the mitochondria fast enough.
• Lactate's fate includes liver conversion, heart fuel, and muscle oxidation.

Citric Acid Cycle (CAC)

• The CAC takes place in the mitochondrial matrix.
• The main location of the electron transport chain (ETC) is the inner mitochondrial membrane.
• Acetyl CoA binds to oxaloacetate.
• Citrate is the product of Acetyl CoA binding to oxaloacetate.
• The products per turn of the CAC are 3 NADH, 1 FADH2, 1 ATP, and 2 CO2.
• Oxidation of NADH/FADH2 for ATP production occurs via the ETC.
• Approximately 2.5 ATP are produced per mitochondrial NADH.
• Approximately 1.5 ATP are produced per mitochondrial FADH2.

Fat Metabolism

• The main fat storage form is triglycerides.
• Triglyceride breakdown is called lipolysis.
• Lipolysis occurs in adipose and muscle tissue.
• Beta-oxidation breaks fatty acids into Acetyl CoA.
• Protein use for energy begins with deamination.
• Carbon skeletons are amino acids without the NH2 group.
• Carbon skeletons enter the CAC, glycolysis, or gluconeogenesis.
• Gluconeogenesis occurs mainly in the liver.
• Fatty acids cannot become glucose because Acetyl CoA can't enter gluconeogenesis.
• Approximately 32 ATP are produced from one glucose oxidation.
• Approximately 120 ATP are produced from an 18-carbon fatty acid.
• "Fat burns in the flame of carbohydrate" means pyruvate makes oxaloacetate which is needed for fat metabolism in the Krebs cycle.
• Excess Acetyl CoA leads to the production of ketone bodies.
• Acetoacetate is a ketone body formed from 2 Acetyl CoA molecules.
• Ketosis means there are high ketone levels in the blood.
• A 20-carbon fatty acid yields more ATP than a 16-carbon fatty acid.
• Reduced compounds have more chemical energy.
• Shorter metabolic processes yield less ATP.
• The body stores more fat than other macronutrients.