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EXAM REVIEW

EXAM REVIEW. EXAM I CLASS AVERAGE = 59.1 EXAM II CLASS AVERAGE= 71.7 The class increased the average by 12.6 points!! 21/41 (51%) students received a C or better 31/41 (76%) students received a D or better. EXAM II Grade Distribution. NUMBER OF STUDENTS. GRADE. Trouble Spots.

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EXAM REVIEW

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  1. EXAM REVIEW

  2. EXAM I CLASS AVERAGE = 59.1 EXAM II CLASS AVERAGE= 71.7 The class increased the average by 12.6 points!! 21/41 (51%) students received a C or better 31/41 (76%) students received a D or better

  3. EXAM II Grade Distribution NUMBER OF STUDENTS GRADE

  4. Trouble Spots • Question 2 • Question 5 • Question 7 • Questions 30-33 • Question 35 • Question 40 • Question 44 • Questions 46-49

  5. NEXT EXAM APRIL 12, 2011 COVERS WEEKS 7, 8, 9 and 10

  6. WEEK 8 Glycolysis-Review (anaerobic) Fermentation (anaerobic) Cellular Respiration (aerobic) The Metabolic Pool Pages 134-147

  7. Production of Energy from Food = CellularRespiration I. Anaerobic (no oxygen used) a. Glycolysis- Net gain of 2 ATP b. Fermentation – No ATP gained II. Aerobic (continuing from Glycolysis w/ Oxygen) b. The preparatory reaction c. Citric Acid Cycle d. Electron Transport Chain and chemiosmosis

  8. If OXYGEN is Present: Pyruvate enters the mitochondria  Cell Respiration If OXYGEN is not Present: Pyruvate enters an anaerobic process called fermentation

  9. Glycolysis Review • Anaerobic Process • No oxygen required • Occurs outside the mitochondria • Produces 2, 3-C Pyruvate molecules

  10. OXIDATION REDUCTION LOSS OF ELECTRONS GAIN OF ELECTRONS RED-OX REACTION

  11. OXIDATION REDUCTION L E O the lion says GERRRR LOSS OF ELECTRONS GAIN OF ELECTRONS Page 134 H lost from glucose H transferred to water

  12. The 4 Steps of Cellular Respiration GLUCOSE  2 pyruvate molecules Oxidation  NADH Net gain of 2 ATP • GLYCOLYSIS- -does not require O2 -Is therefore, anaerobic -Occurs OUTSIDE of the mitochondria • PREPARATORY REACTION -Requires O2 -Is therefore, aerobic -Takes place INSIDE of the mitochondria (matrix) • CITRIC ACID CYCLE -Requires O2 -Is therefore, aerobic -Takes place INSIDE of the mitochondria (matrix) • ELECTRON TRANSPORT CHAIN -Requires O2 -Is therefore, aerobic -Takes place INSIDE of the mitochondria (cristae) PYRUVATE  Two C Acetyl Group +CO2 This occurs 2X b/c 2 pyruvates are produced in glycolysis More oxidation  NADH +FADH2 More CO2 is released This cycle occurs 2X b/c 2 Acetyl groups Were produced in the PREP Rxn. 2 ATP gained (1 per cycle) NADH +FADH2 give up e- to the “chain” (series of proteins in mito. cristae) e- are transported from high to low energy states 32 ATP are produced via “chemiosmosis”

  13. STEP/PHASE 1. Glycolysis Occurs within the cytoplasm outside of the mitochondria Is the breakdown of GLUCOSE into 2 pyruvate molecules 2-ATP molecules are used to “jump-start” the reactions in glycolysis Page 138, section 8.2

  14. Glycolysis Begins as glucose diffuses into the cytoplasm of the cell from the blood stream 2 ATP are used to add 2 phosphate groups to the glucose, thereby energizing the Glucose molecule The energized glucose molecule splits apart and creates 2 PGAL (phosphoglyceraldehyde) molecules

  15. Glycolysis ATP is used to add a phosphate group to the ends of the glucose molecule This addition of phosphates energizes the glucose molecule The energized glucose splits into 2 G3P molecules (3-carbon molecules)

  16. Glycolysis G3P gets oxidized as NAD+ gets reduced 2 BPG molecules are produced via the addition of phosphate onto the ends of G3P

  17. Glycolysis phosphoenol pyruvate(PEP) ATP is created as ADP is phosphorylated Note the loss of the phosphate group from the 3-C molecules as ATP is created

  18. Glycolysis Metabolic Pathway NET GAIN OF 2 ATP

  19. Fermentation • Break down of glucose in the absence of O2 • Anaerobic • Occurs after glycolysis • Occurs if there is a continued absence of oxygen • Pyruvate is turned into “waste product” • No more energy is produced • What organisms do fermentation? • Bacteria • Yeast • Animals

  20. Two types of Fermentation • Lactic Acid Fermentation (fungi, bacteria, muscles) Pyruvate  Lactic Acid (C3H6O3) + NAD+ • Alcohol Fermentation (yeasts) Pyruvate Ethanol (C2H5OH) + Carbon Dioxide (CO2) + NAD+

  21. Lactic Acid Fermentation • Pyruvate is reduced by NADH to lactate (pyruvate receives electrons from NADH  NAD+) • WHY do Fermentation? • NAD+ is generated which can be “recycled” for reuse in earlier reactions • NAD+ can be reduced to NADH and then NADH can reduce pyruvate once again • ATP is continuously produced even w/o the presence of oxygen, albeit very little ATP is generated (only 2 ATP!)

  22. Fig. 8.5 pg 138

  23. Advantages/Disadvantages of Fermentation • Anaerobic bacteria and yeast can be used to produce food products • Ex. yeast fermentation yield CO2  bread rises • Ex. yeast fermentation yields alcohol  produce wine and beer (fermentation of fruit= wine, fermentation of grain = beer) • Ex. bacteria convert alcohol to acid (vinegar) • Production of yogurt, cheese, sour cream via bacterial fermentation See page 139, Chapter 8

  24. Advantages/Disadvantages of Fermentation • Lactic acid fermentation is critical for certain animals and tissues • Animals use lactic acid for rapid bursts of energy • Lactic acid fermentation provides continued production of ATP in absence of oxygen via the cycling of NAD+ • Lactic acid and alcohol are toxic to cells, bacteria and yeasts • Lactic acid build up in humans causes change in pH in blood • Continued lack of O2 = oxygen debt (amount of oxygen needed to rid body of lactic acid), heavy breathing after exercise recovery

  25. Glycolysis2 ATP 2 NADH 2 Pyruvate With OXYGENWithout OXYGEN • a. The preparatory reaction • b. Citric Acid Cycle (2 ATP) • Electron Transport Chain and chemiosmosis • TOTAL of 36-38 ATP produced Lactic Acid Fermentation OR Alcohol Fermentation TOTAL of 2 ATP Produced

  26. Cellular Respiration (Oxygen present) After glycolysis occurs in the cytoplasm: • Prep Reaction (mitochondrial matrix) • Citric Acid Cycle/Krebs Cycle (mitochondrial matrix) • Electron Transport Chain (cristae)

  27. Cellular Respiration C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY (Required!) HIGH ENERGY LOW ENERGY LOW ENERGY ENERGY RELEASED Product of Glucose Breakdown/ Bonds Broken

  28. Inside the Mitochondria Majority of the ATP produced from the breakdown of Glucose occurs in the Mitochondria !

  29. a. The Preparatory Reaction • Occurs after glycolysis and before the Citric Acid Cycle/Krebs Cycle • The prep reaction converts the two 3-C pyruvate to two 2-C acetyl group and CO2 is released • This is done with the help of Coenzyme A

  30. Pg. 140 Chpt. 8 THE PREP REACTION Glycolysis Electrons are removed from PYRUVATE by NAD+ = Pyruvate is OXIDIZED One prep reaction per pyruvate = 2 acetyl-CoA

  31. Coenzyme A is a MOLECULE A molecule of coenzyme A carrying an acetyl group is referred to as acetyl-CoA Coenzyme A oxidizes PYRUVATE

  32. Prep Reaction • CO2 is released (to blood) as Pyruvate is carried into the • mitochondria • 2. NAD+ oxidizes Pyruvate yielding NADH + H+ • 3. Coenzyme A oxidizes Pyruvate • FINAL PRODUCT is TWO Acetyl CoA molecules

  33. b. The Citric Acid Cycle/Krebs Cycle Coenzyme A transfers the 2-C acetyl group in the form of Acetyl CoA to the CAC/Krebs Cycle Glycolysis PREP rxn.

  34. (from prep rxn) Pg 141, Chpt. 8

  35. CAC/ Krebs Cycle NADH

  36. Acetyl group joins with 4-C Oxaloacetate to form 6-C Citrate • Oxidation occurs when NAD+ accepts e- (3X) and FAD accepts e- (1X) • The acetyl group is oxidized to TWO CO2 molecules (4 total) • Substrate level ATP synthesis occurs (an enzyme passes a high energy • P to ADP to form ATP • A total of 6 CO2 molecules are produced, 2 from prep rxn, 4 from CAC • per glucose molecule • 6. NADH and FADH2 are carrying high energy Phosphates!!

  37. What happens to the high energy NADH and FADH2 molecules? • These molecules carry electrons to the ELECTRON TRANSPORT CHAIN in the CRISTAE of the mitochondria STEP I. NADH  NAD+ + 2 H+ FADH2 FAD + 2 H+ -NADH and FADH2 bring electrons to the ETC -Both molecules are oxidized in order for ADP to produce ATP

  38. The ETC Players COMPLEX I- NADH-Q reductase (COMPLEX II- Succinate CoQ Reductase) COMPLEX III- Cytochrome b-c reductase COMPLEX IV- Cytochrome c Oxidase ATP SYNTHASE COMPLEX Cytochrome c Coenzyme Q NADH Hydrogen Ions ATP FADH2 Electrons

  39. ELECTRON TRANSPORT CHAIN pg 142 Electrons are passed from protein carrier to carrier via a series of oxidation-reduction reactions. Protein Carriers: COMPLEX I NADH-Q reductase = An enzyme that catalyzes the transfer of electrons from NADH to Coenzyme Q Coenzyme Q/Ubiquinone = An enzyme that Transfers Electrons from Complex I and Complex II to Complex III Cytochrome b-c reductase/Complex III = helps build proton gradient Cytochrome c = electron carrier, transfers Electrons from one protein to another Complex II Succinate CoQ Reductase= oxidizes FADH2 Cytochrome c Oxidase/Complex IV = Electrons are transferred to oxygen to produce water

  40. STEP I. NADH  NAD+ + 2 H+ FADH2 FAD + 2 H+ STEP II. NADH-Q reductase/Complex I gains electrons and is reduced. HYDROGEN IONS are pumped into the inner membrane space. Complex II oxidizes FADH2 to FAD + 2H+ STEP III. Electrons are lost to CoEnzymeQ which transfers the electrons to Complex III (cytochrome reductase) STEP IV. Hydrogen from the reduction of FADH2 from complex II are pumped to inner membrane space via Cytochrome reductase/ Complex III STEP V. Cytochrome cand coenzyme Q continuously shuttle electrons from complex to complex Cyt c and Coenzyme Q only transport electrons STEP VI. Oxygen accepts electrons from complex IV, cytochrome c oxidase, combines with hydrogen and produces H2O

  41. OXYGEN IS THE FINAL ACCEPTOR OF ELECTRONS IN THE ELECTRON TRANSPORT CHAIN!! Without oxygen, the electron transport chain would cease to function!! Death results if oxygen is not present because the body would not be able to produce/generate ATP

  42. Mitochondrial CRISTAE Matrix

  43. http://vcell.ndsu.edu/animations/atpgradient/first.htm

  44. As HYDROGEN IONS are pumped into the intermembrane space of the mitochondria, an electrochemical gradient develops. Ten times as many H+ are in the intermembrane space as there are in the matrix. This creates a strong [ ] gradient. Hydrogen ions will want to enter the mitochondrial matrix by flowing down the concentration gradient As hydrogen flows down the gradient via the ATP synthase complex, the enzyme ATP SYNTHASE synthesizes ATP from ADP + P ATP production depends on the H+ gradient!! ATP produced in the matrix is quickly shuttled out for use in body

  45. CHEMIOSMOSIS • Movement of Hydrogen Ions from innermembrane to the mitochondrial matrix MATRIX INNERMEMBRANE

  46. ATP SYNTHASE

  47. ATP Synthase • Is an enzyme • Produces ATP from hydrogen ions flowing down their concentration gradient FROM the inner mitochondrial membrane to the matrix • ATP is transported out of the matrix via an ATP channel protein • At any time, the amount of ATP in human body is only enough to sustain 1 minute of life. ATP synthase must work CONSTANTLY

  48. ENERGY YIELD from GLUCOSE METABOLISM 2 ATP from glycolysis 2 ATP from Krebs/ CAC cycle 32 or 34 ATP from Electron Transport Chain TOTAL = 36 or 38 ATP produced per 1 glucose molecule WHY???

  49. 36 or 38 ATP In some cases: -2 NADH are produced during glycolysis -Sometimes NADH cannot cross mitochondrial membranes to go to ETC, but the e- from NADH can be shuttled -This shuttling costs the cell 1 ATP for each NADH that is shuttled which reduces the count of ATP from 38 to 36 -36 is the usual number of ATP produced

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