Lecture Presentation Chapter 24 Metabolic Pathways for Lipids and Amino Acids Karen C Timberlake General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 24 Metabolic Pathways for Lipids and Amino Acids Patients diagnosed with chronic hepatitis C virus (HCV) infection require lifelong monitoring by a specialist team including a public health nurse A public health nurse works in public health departments, correctional facilities, occupational health facilities, schools, and organizations that aim to improve health at the community level General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chapter 24 Readiness Core Chemistry Skills • • • • • • • Identifying Fatty Acids (17.2) Drawing the Zwitterion for an Amino Acid (19.1) Identifying Important Coenzymes in Metabolism (22.3) Identifying the Compounds in Glycolysis (22.4) Identifying the Compounds and Enzymes in Glycogenesis and Glycogenolysis (22.6) Describing the Reactions in the Citric Acid Cycle (23.1) Calculating the ATP Produced from Glucose (23.3) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 24.1 Digestion of Triacylglycerols The fat cells (adipocytes) that make up adipose tissue are capable of storing unlimited quantities of triacylglycerols Adipose tissue (made of adipocytes) stores 85% of the total energy available in the body Learning Goal Describe the sites of and products obtained from the digestion of triacylglycerols General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Digestion of Triacylglycerols In the digestion of fats (triacylglycerols), • • bile salts break fat globules into smaller particles called micelles in the small intestine pancreatic lipases hydrolyze ester bonds to form monoacylglycerols and fatty acids, which recombine in the intestinal lining • phospholipids and proteins coat the fats, forming chylomicrons, which are transported to the cells of heart, muscle, and adipose tissues • lipases hydrolyze triacylglycerols, forming glycerol and free fatty acids, which are oxidized to acetyl CoA molecules for ATP synthesis General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Digestion of Triacylglycerols The digestion of fats begins in the small intestine when bile salts emulsify fats that undergo hydrolysis to monoacylglycerols and fatty acids General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Utilization of Fat When blood glucose is depleted and glycogen stores are low, • • the process of fat utilization is stimulated the hormones glucagon or epinephrine are secreted into the bloodstream, where they bind to receptors on the membrane of adipose tissue • a hormone-sensitive lipase within the fat cells catalyzes the hydrolysis of triacylglycerols to glycerol and free fatty acids • glycerol and fatty acids diffuse into the bloodstream and bind with plasma proteins to be transported to the tissues, muscles, and fat cells General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Metabolism of Glycerol Glycerol from fat digestion • adds a phosphate from ATP to form glycerol-3-phosphate • • undergoes oxidation of the —OH group to dihydroxyacetone phosphate becomes an intermediate in glycolysis and gluconeogenesis General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Metabolism of Glycerol General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Give answers for the following questions about fat digestion: What is the function of bile salts in fat digestion? How is glycerol utilized? General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Solution Match each of the following citric acid intermediates with the amino acid that provides its carbon skeleton: 1) pyruvate 2) fumarate 3) α-ketoglutarate A cysteine 1) Pyruvate B glutamine 3) α-ketoglutarate C aspartate 2) Fumarate D serine 1) pyruvate General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc 24.9 Synthesis of Amino Acids + Plants and bacteria produce all of their amino acids using NH4 – and NO3 • Humans can synthesize of the 20 amino acids found in their proteins • Nonessential amino acids are synthesized in the body, while essential amino acids must be obtained from diet Learning Goal Illustrate how some nonessential amino acids are synthesized from intermediates in the citric acid cycle and other metabolic pathways General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Pathways for Amino Acid Synthesis A variety of pathways are involved in the synthesis of nonessential amino acids • • The body synthesizes nonessential amino acids The α-keto acid carbon skeletons are obtained from the citric acid cycle or glycolysis and converted to amino acids by transamination General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Synthesis of Amino Acids Nonessential amino acids are synthesized from intermediates of glycolysis and the citric acid cycle General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Synthesis of Alanine, Aspartate Nonessential amino acids such as alanine and aspartate are produced by transamination General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Synthesis of Glutamine The synthesis of the other nonessential amino acids may require several reactions in addition to transamination Glutamine is synthesized when a second amino group is added to glutamate using the energy from the hydrolysis of ATP General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Synthesis of Tyrosine Tyrosine, an aromatic amino acid with a hydroxyl group, is formed from phenylalanine, an essential amino acid, and oxygen General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Overview, Metabolism Catabolic pathways • • degrade large molecules form small molecules that enter the citric acid cycle and electron transport to produce energy Anabolic pathways • • use small molecules and energy synthesize larger molecules in the cell In the overall view of metabolism, there are several branch points from which compounds may be degraded for energy or used to synthesize larger molecules General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Overview, Metabolism Core Chemistry Skill Distinguishing Anabolic and Catabolic Pathways General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Match each of the following amino acids with the intermediate needed for its synthesis: 1) alanine 2) glutamate 3) aspartate A pyruvate B oxaloacetate C α-ketoglutarate General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Study Check Match each of the following amino acids with the intermediate needed for its synthesis: 1) alanine 2) glutamate A pyruvate 3) aspartate 1) alanine B oxaloacetate 3) aspartate C α-ketoglutarate2) glutamate General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Phenylketonuria (PKU) In phenylketonuria (PKU), • • • • • the gene that converts phenylalanine to tyrosine is defective phenylalanine forms phenylpyruvate (transamination), which goes to phenylacetate (decarboxylation) high levels of phenylacetate cause severe mental retardation a diet low in phenylalanine and high in tyrosine is recommended sweeteners and soft drinks containing aspartame, which contains phenylalanine as one of the two amino acids in its structure, should be avoided General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Chemistry Link to Health: Phenylketonuria (PKU) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Concept Map General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc ... General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Transport of Fatty Acyl CoA General, Organic, and Biological Chemistry: Structures. .. (16 C/2 – = 7) General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc General, Organic, and Biological Chemistry: Structures of Life,... glycolysis and gluconeogenesis General, Organic, and Biological Chemistry: Structures of Life, 5/e Karen C Timberlake © 2016 Pearson Education, Inc Metabolism of Glycerol General, Organic, and Biological