Metabolism and Catabolism Quiz

Metabolism

• Metabolism is the sum of all chemical reactions involved in catabolism and anabolism.
• Catabolism is the breakdown of large molecules (food) into smaller molecules, releasing energy.
• Anabolism is the use of energy from catabolic reactions to build small molecules into large molecules.

Energy and ATP

• About 40% of energy released from catabolism is transferred to ATP, while 60% is given off as heat.
• ATP is composed of adenine, ribose, and 3 phosphate groups.
• ATP breaks down into ADP and an inorganic phosphate group.

Catabolism of Macromolecules

• Carbohydrates break down into glucose, primarily used for energy.
• Fats break down into glycerol and fatty acids, stored in adipocytes unless needed for energy.
• Proteins break down into amino acids, facilitating protein synthesis in cells.
• Nucleic acids are used for nucleic acid metabolism in each cell.

Hormones

• Catabolic hormones: cortisol, glucagon, epinephrine, and cytokines.
• Anabolic hormones: growth hormone, insulin-like growth factor, insulin, testosterone, and estrogen.

Redox Reactions

• Oxidation is the loss of an electron, with energy transferred to the next molecule.
• Reduction is the gain of an electron.
• Redox reactions are catalyzed by enzymes, involving the removal of hydrogen atoms and electron transfer.

Carbohydrate Metabolism

• Carbohydrates are organic molecules made of carbon, hydrogen, and oxygen.
• Glycolysis is the breakdown of glucose to create ATP, NADH, and pyruvate.
• Anaerobic respiration occurs without oxygen, converting pyruvate to lactic acid.
• Aerobic respiration occurs with oxygen, converting pyruvate to ATP through the Krebs cycle.

Krebs Cycle and Electron Transport Chain

• The Krebs cycle (Citric Acid Cycle) converts pyruvate into acetyl CoA, producing ATP, NADH, and FADH2.
• The Electron Transport Chain (ETC) generates ATP using NADH and FADH2, transferring electrons to oxygen.

Lipid Metabolism

• Lipid metabolism is the oxidation of fatty acids to generate energy or synthesize new lipids.
• Triglycerides are broken down by pancreatic lipase and emulsified by bile salts.
• Lipolysis is the breakdown of fat stores for energy.
• Ketogenesis occurs during low carbohydrate intake, fasting, or starvation, producing ketone bodies.

Protein Metabolism

• Protein is used for growth and repair, and can also be used as fuel.
• Excess protein is converted to glucose or triglycerides and stored in energy reserves.
• The urea cycle produces urea from ammonium ions, removing nitrogenous waste.

Metabolic States

• The Absorptive state is the digestive and absorptive phase, lasting up to 4 hours.
• The Postabsorptive state is a fasting state, relying on stored glycogen and promoting gluconeogenesis.
• The Starvation state is a survival mode, prioritizing glucose to the brain, conserving amino acids, and eventually using ketones for fuel.

Thermoregulation

• Thermoregulation maintains body temperature near 98.6°F in times of heat and cold.
• About 60% of energy production is in the form of heat, maintaining body temperature.
• The hypothalamus controls sweating and shivering to regulate body temperature.

Metabolic Rate and Energy

• The Metabolic Rate is the energy consumed minus energy expended.
• Basal Metabolic Rate (BMR) is the energy expended at rest, in a neutral environment, and in a postabsorptive state.
• A calorie is the amount of heat required to raise 1 g of water by 1°C.
• Overweight and obesity occur when consuming more calories than expended.

Vitamins

• Vitamins are organic compounds essential for biochemical reactions in the body.
• Vitamin B plays a significant role in metabolism.