anim_lipid_metabolism_answer_key.doc

Lipid Metabolism To complete this worksheet, select:         Module:  Energy Acquisition         Activity:  Animations         Title:  Lipid Metabolism Introduction 1. What are the products following hydrolyzation (digestion) of lipids? fatty acid and glycerol 2. Within cells, what are two functions of fatty acids and glycerol? When oxidized, they can be used to generate ATP or used to produce triglycerides for energy storage. Lipid Catabolism 3. a. Define lipolysis and explain why it is important. Lipolysis is the process that breaks down lipids into fatty acids and glycerol. b. List hormones that stimulate lipolysis. Epinephrine, norepinephrine, cortisol, thyroid and human growth hormones. 4. a. Describe Beta-Oxidation. Beta-oxidation is a series of reactions that form acetyl coenzyme A from a 2-carbon fragment of a fatty acid chain and coenzyme A. b. In what form do the beta-oxidized fatty acids enter the Krebs cycle? Acetyl coenzyme A c. Reduced coenzymes are produced in the Krebs cycle. How are they used? They are used to generate ATP in the electron transport chain. d. Explain how ketoacidosis occurs. This occurs when there is overproduction of ketone bodies (ketosis) which can lead to acidosis of the blood (ketoacidosis). 5. a. How do glycerol molecules enter the Krebs cycle? Glycerol is converted to pyruvic acid, which is used to form acetyl coenzyme A, where it enters the Krebs cycle. b. Reduced coenzymes are produced in the Krebs cycle. How are they used? To generate ATP in the electron transport chain c. Alternatively, glycerol can enter the glycolytic pathway. What is formed from glycerol if this happens? Glucose d. What hormones stimulate gluconeogenesis? Glucagon and cortisol Lipid Anabolism 6. a. Define lipogenesis. Lipid anabolism b. What hormone stimulates lipogenesis? Insulin c. Where does lipogenesis occur? In liver and adipose cells d. Briefly describe how fatty acids are anabolized (built). New lipids are synthesized from acetyl coenzyme A and glucose molecules. Acetyl coenzyme A molecules are produced from amino acids, glucose, and ketone bodies, which are converted to fatty acids. e. Briefly describe how glycerol is anabolized. Through the formation of glyceraldehyde phosphate glucose is converted to glycerol. f. How are triglycerides and phospholipids anabolized? Glycerol and fatty acids become triglycerides and phospholipids through a series of anabolic reactions.