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Announcements

Announcements

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Announcements

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  1. Announcements • My Pyramid extra credit project is due TODAY! • You should have turned your labs in/made up your quizzes already. • Cell/Pedigree extra credit projects are due next week.

  2. Announcements • FINAL EXAM • cumulative • 2 hrs • starts at 11am in this room • you can use a periodic table and calculator • NO CELL PHONES!

  3. Announcements • Celebrate the end of Bio 099 at the Outback Steakhouse next Saturday from 2-4pm • Here’s the address: • 615 Bel Air Rd Bel Air MD 21014

  4. An overview of Metabolism Bio 099 December 8, 2007

  5. Metabolism • Metabolism is all the chemical reactions that occur in a living organism.

  6. Catabolism • Catabolism is the breakdown or digestion of organic molecules. Catabolic reactions release energy in the form of ATP, which the cell can then use for its various functions.

  7. What molecules does the cell break down for energy? • Usually fats and carbohydrates are the fuel of choice • Triglycerides = • fatty acids + glycerol • Glycogen = • monosaccharides

  8. Glycogen • most abundant storage of carbohydrate • a branched chain of glucose molecules

  9. Triglycerides • most abundant storage of lipids • primarily of fatty acids

  10. Proteins • most abundant organic components in body • perform many vital cellular functions

  11. Metabolism Handout

  12. Tools for making ATP • To survive cells need to make ATP. • For ATP synthesis the following are required: • oxygen

  13. Tools for making ATP • To survive cells need to make ATP. • For ATP synthesis the following are required: • oxygen • nutrients/vitamins

  14. Tools for making ATP • To survive cells need to make ATP. • For ATP synthesis the following are required: • oxygen • nutrients/vitamins • mitochondria

  15. Tools for making ATP • To survive cells need to make ATP. • For ATP synthesis the following are required: • oxygen • nutrients/vitamins • mitochondria • enzymes

  16. Why are catabolic reactions necessary for the cell? • To release energy for anabolic reactions!

  17. Anabolism • Anabolism is the production of new organic molecules using cellular energy (ATP). For example: Proteins are produced through an anabolic reaction that uses ATP to form polypeptide bonds between amino acids.

  18. Why is anabolism necessary? • Metabolic Turnover: The cell needs energy to periodically replace its components. • Growth and Division: In order to grow and divide a cell needs energy. • Special Processes: Depending on the specific cell type, various functions require energy. • For example: muscle cell contraction requires energy. • Nutrient Pool: A cell keeps a reserve storage of nutrients, just in case…

  19. Catabolism: Aerobic Cellular Respiration

  20. Aerobic Cellular Respiration:generating ATP for the cell • Glycolysis • Krebs cycle (TCA) • Electron transport chain

  21. Aerobic Cellular Respiration • Glycolysis • Krebs cycle (TCA) • Electron transport chain happens only in the presence of oxygen aerobic: requires or takes place in the presence of oxygen

  22. Mechanisms of ATP synthesis • substrate-level phosphorylation occurs during glycolysis and Kreb’s cycle ADP + P  ATP • oxidative phosphorylation occurs during the electron transport chain formation of a proton (H+) gradient across the inner mitochondrial membrane provides potential energy to make ATP

  23. Oxidation-reduction (redox) reactions are important in metabolism • Oxidation: a molecule is oxidized when it loses electrons. • Reduction: a molecule is reduced when it gains electrons. During metabolism enzymes catalyze these reactions

  24. Example of a redox reaction:NAD+ • Nicotinamide adenine dinucleotide (NAD+) is a coenzyme that carries electrons to be used in the electron transport chain. • NAD+ is made from the vitamin niacin.

  25. Example of a redox reaction:FAD+ • flavin adenine dinucleotide (FAD) is a coenzyme that carries electrons to be used in the electron transport chain. • FAD contains riboflavin (vitamin B2).

  26. Carbohydrate Catabolism • generates ATP by breaking down sugar C6H12O6 + 6O2 6H2O + 6CO2 = 36 ATP + heat 1 molecule of glucose nets 36 molecules of ATP

  27. Glucose must first get into the cell • insulin binds to its receptor to tell the cell glucose is coming and to add glucose transporter proteins to the membrane. • glucose is transported into the cell through facilitated diffusion

  28. Carbohydrate Metabolism • Glycolysis: always happens first.

  29. Glycolysis • STEP 1. • Hexokinase phosphorylates glucose creating glucose-6-phosphate • uses 1 ATP molecule • traps glucose molecule within cell

  30. Glycolysis STEP 2. Phosphoglucoisomerase transforms glucose-6-phosphate to fructose-6-phophate

  31. Glycolysis STEP 3. Phosphofructokinase (PFK) adds a phosphate to fructose-6-phophate making it Fructose 1, 6 bisphosphate. This reaction requires 1 ATP.

  32. Glycolysis STEP 4. An enzyme splits Fructose 1, 6 bisphosphate into 2 glyceraldehyde-3-phosphates molecules.

  33. Glycolysis STEP 5. Each glyceraldehyde-3-phosphate is oxidized to 1,3-bisphosphoglycerate. At the same time NAD+ is reduced to NADH. NAD+ also donates a phosphate group in the reaction

  34. Glycolysis STEP 6. Each 1,3-bisphosphoglycerate is striped of its phosphate groups making 3-Phosphoglycerate. The phosphates are used to generate ATP from ADP (2 total)

  35. Glycolysis STEP 7&8. 2 more enzymatic reactions form phosphoenolypyruvate (PEP).

  36. Glycolysis STEP 9. PEP is converted to pyruvategenerating ATP

  37. Glycolysis Each Glucose makes 2 molecules of glyceraldehyde phosphate so from that point on, multiply everything by 2: = 2 NADH = 4 ATP

  38. ATP is used in 2 reactions at the beginning of glycolysis: Glycolysis: Take home message

  39. ATP is used in 2 reactions at the beginning of glycolysis: to keep glucose in the cell to make the molecule that is then broken in half Glycolysis: Take home message

  40. ATP is used in 2 reactions at the beginning of glycolysis: to keep glucose in the cell to make the molecule that is then broken in half 4 ATP and 2 NADH are generated in the last half of glycolysis, Glycolysis: Take home message

  41. ATP is used in 2 reactions at the beginning of glycolysis: to keep glucose in the cell to make the molecule that is then broken in half 4 ATP and 2 NADH are generated in the last half of glycolysis 2 pyruvate molecules are generated from glycolysis. Glycolysis: Take home message

  42. Carbohydrate Metabolism • Glycolysis • Pyruvic acid transition

  43. The fate of pyruvic acid • In the absence of oxygen (anaerobic) • The Electron Transport Chain (ETC) cannot run because O2 is the final electron acceptor • Because NADH2 cannot unload its H ions in the ETC it returns them to pyruvic acid forming lactate • This often happens in the muscle cells during exercise

  44. The fate of pyruvic acid • By the way… this is also how we make alcohol from sugar: fermentation

  45. The fate of pyruvic acid • In the presence of oxygen (aerobic) • First, Pyruvic acid will enter the mitochondria where it is converted to acetyl CoA:

  46. The fate of pyruvic acid • In the presence of oxygen (aerobic) • First, Pyruvic acid will enter the mitochondria where it is converted to acetyl CoA: • CO2 is removed • H ions leave and reduce NAD+ to NADH2 • coenzyme A is added giving acetyl CoA

  47. The fate of pyruvic acid • In the presence of oxygen (aerobic) • First, Pyruvic acid will enter the mitochondria where it is converted to acetyl CoA: • CO2 is removed • H ions leave and reduce NAD+ to NADH2 • coenzyme A is added giving acetyl CoA • Next, Acetyl CoA enters the Krebs Cycle and continues aerobic cellular respiration.

  48. Carbohydrate Metabolism • Glycolysis • Pyruvic acid transition • Kreb’s cycle

  49. Kreb’s Cycle (TCA, citric) • Acetyl CoA combines with oxaloacetic acid to form citric acid

  50. Kreb’s Cycle (TCA, citric) • Acetyl CoA combines with oxaloacetic acid to form citric acid • as the cycle continues carbons are removed, forming CO2 and NAD/FAD are reduced to NADH/FADH (electron carriers)