Human Anatomy and Physiology II

1. Human Anatomy and Physiology II Biology 1414 Unit 8 Metabolism and Nutrition

2. Objective 1 Define metabolism and differentiate between catabolism and anabolism. Be able to apply the latter two terms to various metabolic reactions. Unit 8 - Objective 1

3. Definition of Metabolism Metabolism is defined as the sum total of all chemical reactions that occur in the body. Unit 8 - Objective 1

4. Catabolism Catabolism is that part of metabolism that involves the break down of large, complex molecules into smaller, more simplified products. This occurs during digestion, removal of hydrogen (dehydrogenation), carboxyl groups (decarboxylation) and amino groups (deamination), oxidation, etc. Unit 8 - Objective 1

5. Anabolism Anabolism is that part of metabolism that involves the synthesis of larger, more complex moleculesfrom small, simplereactants. Examples of anabolism would include the synthesis of glycogen from glucose, protein from amino acids, fatfrom glycerol and fatty acids and construction of new antibodies and new enzymes. Unit 8 - Objective 1

6. Objective 2 Indicate the location of , diagram and describe the major metabolic pathways involved in the catabolism of glucose to carbon dioxide and water. Indicate where hydrogens are given off, where ATP is made where oxygen is utilized, where water is produced and identify key assigned intermediates. Unit 8 - Objective 2

7. Glucose Catabolsm Glucose Catabolism is one of the primary metabolic events that occurs during cell metabolism. The portion of cell metabolism that breaks down glucose is generally called cellular respiration. Cellular respiration has three major events; glycolysis, the Krebs cycle and the electron transport system (ETS). Unit 8 - Objective 1

8. Location of the Major Metabolic Pathways MetabolicPathwayLocation Glycolysis Cytoplasm Krebs Cycle Mitochondria (matrix) Electron Transport Mitrochondria System (cristae) Unit 8 - Objective 2

9. Events of Glycolysis In phase one, Glycolysis takes in glucose as a “fuel” and transforms it into a “super active” intermediate compound called Fructose-1,6-Diphosphate(F-1,6-DP). This is accomplished by using two ATP molecules to phosphorylate the sugar at carbons 1 and 6. In phase two, the F-1,6-DP sugar then splits (lysis) into two, half sized sugar fragments which become Glyceraldehyde Phosphate and Dihydroxyacetone Phosphate. Unit 8 - Objective 2

10. Events of Glycolysis In phase three, the two half sized intermediates are oxidized down to two pyruvic acid molecules. During this process, inorganic phosphate is added from the substrate of the cytoplasm to each intermediate, hydrogen along with its electrons are removed from each intermediate, NAD picks up the hydrogens for transport and all of the phosphate is removed (4 total) from the intermediates. This phosphate is added to ADP to form four ATP molecules. Unit 8 - Objective 2

11. Events of Glycolysis The removal of hydrogen is calleddehydrogenation and is an oxidation process. When NAD picks up hydrogen, a reductionprocess occurs. The addition of phosphate is called phosphorylation and results in the netproduction of two ATP molecules ( two used up in phase one minus four produced in phase three). The overall transformation of glucose into two pyruvic acids is also an oxidation process. Unit 8 - Objective 2

12. Events of Glycolysis Examine the following slide in order to visualize the event of Glycolysis. Unit 8 - Objective 2

13. Summary of Glycolysis

14. Events of The Krebs Cycle The Krebs cycle is named after Hans Krebs and is a metabolic event that follows glycolysis. This process occurs in the fluid matrix of the mitochondrion, uses the pyruvic acid from glycolysis and is aerobic. To begin the Krebs cycle, pyruvic acid is converted to acetyl COA. Unit 8 - Objective 2

15. Conversion of Pyruvic Acid to Acetyl COA The conversion of pyruvic acid to acetyl COA is a three step process: 1. First, each of the two pyruvic acids are decarboxylated . At this point, two carbon dioxides are produced and diffuse to the blood. This event yields two acetyl groups. 2. Next, hydrogen is removed from each acetyl group and added to NAD.The removal of hydrogen is called dehydrogenation which is an oxidation process. The addition of hydrogen to NAD is a reduction process. 3. Finally, COA is added to each acetyl group. Unit 8 - Objective 2

16. Events of The Krebs Cycle AcetylCOA which results from the conversion of pyruvic acid then reacts with oxaloacetate using an enzyme called citrate synthase. This results in the first major product of the Krebs cycle called citric acid. Because of this, the Krebs cycle is sometimes called the citric acid cycle. The citric acid is then systematically decarboxylated and dehyrogenated in order to use up the acetyl groups that were attached to the oxaloacetate. This allows oxaloacetate and COA to be used in the next cycle. Unit 8 - Objective 2

17. Events of The Krebs Cycle The conversion of citric acid back to oxaloacetate involves three dehydrodenations that form three reduced NAD (NADH2) molecules, one dehydrogenation that forms one reduced FAD (FADH2), two decarboxylations that form two carbon dioxides and one substrate phosphoporylation that forms an ATP molecule. When two acetylCOA’s are utilized, two cycles occur and the above output is doubled. Unit 8 - Objective 2

18. Output of The Krebs Cycle 1. Six CO2 molecules 2. Eight reduced NAD molecules (NADH2) 3. Two reduced FAD molecules (FADH2) 4. Two ATP molecules Unit 8 - Objective 2

19. Events of The Krebs Cycle Examine the following slide in order to visualize the events of the Krebs Cycle. Unit 8 - Objective 2

20. Summary of the Krebs Cycle

21. Events of the Electron Transport System (ETS) The electron transport system can also be called the electron transport chain. This metabolic process uses the reduced NAD and FAD that is produced by glycolysis and the Krebs cycle. The ETS takes place in the cristae of the mitochondrion and uses oxygen directly (aerobic). This system contains respiratory enzyme complexes that include iron compounds called cytochromes. The cytochromes accept hydrogen from NAD and FAD. Unit 8 - Objective 2

22. Events of the Electron Transport System After receiving hydrogen, the cytochromes split hydrogen into an electron and a hydrogen ion. Electrons from hydrogen are passed through the chain to oxygen. Hydrogen ions are passed into the space between the inner and outer membane of the mitochondrion where they accumulate and create an elevated hydrogen potential. The high potential causes the hydrogen ions to pass through an ATP synthase protein portal. Unit 8 - Objective 2

23. Events of the Electron Transport System The hydrogen from NAD will yield 3 ATP’s and the hydrogen from FAD will yield 2 ATP’s. The ETS will process 10 reduced NAD’s from glycolysis and the Krebs cycle to yield 30 ATP’s.The ETS will also process 4 reduced FAD’s from the Krebs cycle to yield 4 ATP’s. The hydrogen ions that pass back into the mitochondrial matrix then combine with the oxygen that has gained electrons to form water. Unit 8 - Objective 2

24. Summary of the Electron Transport System When hydrogen loses electrons in the ETS, this is called oxidation. When Oxygen accepts those electrons, it is called reduction. When ATP synthase adds phosphate to ADP when it passes hydrogen ions to reduced oxygen, this process is called oxidative phosphorylation. The addition of hydrogen ions to oxygen creates enough water to yield a net of 6 waters for the process of cellular respiration. Make note of this when you observe the slide for Objective 3. Unit 8 - Objective 2

25. Summary of the Electron Transport System Examine the following slides in order to visualize the events of the electron transport system. Unit 8 - Objective 2

26. Processing Reduced NAD in the ETS

27. Processing Reduced FAD in the ETS

28. Oxidative Phosphorylation

29. Summary of Total ATP Production Examine the following slide in order to view the summary of total ATP production in Glycolysis, the Krebs cycle and the Electron Transport System. Unit 8 - Objective 2

30. ATP Formation During Cellular Respiration

31. Objective 3 Write the general balanced equation that shows the catabolism of glucose to carbon dioxide and water. Include in the equation the formation of ATP from ADP and phosphate and oxygen utilization. Unit 8 - Objective 3

32. General Equation for Cellular Respiration C6H12O6 + O6 + 36 ADP + 36 PO4 6CO2 + 6H2O + 36 ATP + Heat Unit 8 - Objective 3

33. Objective 4 Diagram and describe how lipids and proteins are catabolized into carbon dioxide and water. Unit 8 - Objective4

34. Catabolism of Lipids Lipids such as triglycerides are broken down to fatty acids and glycerol. Fatty acids are broken down to acetylCOA through a process of beta oxidation. AcetylCOA is then taken into the Krebs cycle and converted into carbon dioxide, reduced NAD and FAD and ATP. Glycerol is converted into Glyceraldehyde phosphate or dihydroxyacetone phosphate in Glycolysis and converted into reduced NAD , ATP and pyruvic acid. Unit 8 - Objective 4

35. LIPID METABOLISM

36. Catabolism of Proteins Proteins are broken down to amino acids. Amino acids are deaminated and converted into metabolic fragments. For example, glycine is converted into an acetyl group that can become acetyl COA. AcetylCOA is then broken down in the Krebs cycle as discussed in the slide before last. The amine group from glycine is then used as part of urea formation. Unit 8 - Objective4

37. Amino Acid Metabolism

38. Summary of Lipid and Protein Catabolism View the following slide for a summary of lipid and protein catabolism Unit 8 - Objective 5

39. Catabolism of Lipids and Proteins

40. Objective 5 Describe what is meant by the following: beta oxidation, deamination, glycerol catabolism, ketone body formation, fatty acid catabolism, amino acid catabolism. Unit 8 - Objective 5

41. Beta Oxidation Beta oxidation is a catabolic process that breaks downfatty acidstwo carbon units at a time. The two carbon units become acetyl groups that are converted into acetyl COA. An acetyl COA is then used in the Krebs Cycle to make one ATP , 3 NADH2 and 1 FADH2. If a fatty acid has 18 carbon units, then 9 acetyl COA units would be made. Think how much extra ATP and reduced NAD And FAD can be made because of this! Unit 8 - Objective 5

42. Deamination Deamination is a catabolic process that removes an amino group from an amino acid in preparation for its use in the Krebs Cycle or a similar metabolic pathway. Unit 8 - Objective 5

43. Glycerol Catabolism When fat is digested it is broken down to glycerol and fatty acids. Glycerol is then converted to glyceraldehyde phosphate (GALP) and used at a mid point in glycolysis (see Glycolysis in Objective 2). The GALP is then broken down to form ATP, reduced NAD and pyruvic acid. Unit 8 - Objective 5

44. Fatty Acid Catabolism When fat is digested it is broken down to glycerol and fatty acids. The fatty acids are then broken down by the process of beta oxidation to produce acetyl COA as discussed in a previous slide. Unit 8 - Objective 5

45. Ketone Body Formation If a person is not getting enough glucose through the diet (rare!) because of fasting, starvation, etc. or if glucose is not being transferred from the blood to body cells (as in diabetes mellitus), then oxaloacetate from the Krebs Cycle is converted to new glucose. Without oxaloacetate, Acetyl COA cannot be used and accumulates. The liver then converts excess acetyl COA into ketones (acetone, acetoacetate, etc.). These ketones are acidic and as they accumulate, they cause ketoacidosis. Unit 8 - Objective 5

46. Amino Acid Catabolism If more amino acids accumulate than can be used in the synthesis of new proteins, then they can be catabolized or broken down by a process called deamination. Deamination removes amino groups from the amino acid to yield a fragment that can be used in the Krebs Cycle. Unit 8 - Objective 5

47. Objective 6 Discuss the role of LDL, HDL and saturated fats in cholesterol metabolism. Unit 8 - Objective 6

48. Role of LDL in Cholesterol Metabolism LDL stands for low density proteins made in the liver. These metabolic units contain small portions of phospholipids an triglycerides and large quantities of cholesterol. The LDL is designed to transport its stored materialfromthe liver to cells and tissues. Cholesterol fromLDL’s can be transported toblood vessels and stored as part of plaque deposits Unit 8 - Objective 6

49. Role of HDL in Cholesterol Metabolism HDL stands for high density lipoprotein which is made in tissues during increased activity. This metabolic unit transports phospholipid, triglyceride and cholesterol from tissues, including blood vessels, back to the liver. The cholesterol that is transported back to the liver is converted into Bile which is excreted and stored in the gall bladder. This is a good way to eliminate cholesterol from the body. Unit 8 - Objective 6

50. Role of Saturated Fats in Cholesterol Metabolism Saturated fats are triglycerides that contain fatty acids that have a full compliment of hydrogen. This type of fat stimulates the liver to make cholesterol for storage in body tissues and to inhibit the release of cholesterol from the body. In terms of good nutrition it is recommended that unsaturated fats be substituted for saturated fats a high percentage of the time in the diet. Unit 8 - Objective 6