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Cellular Respiration

Cellular Respiration. Identify major stages of the process Location of each stage Describe structures Illustrate with simple diagrams Indicate how ingredients are acquired/products released Factors that affect the rate of respiration. The stages.

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Cellular Respiration

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  1. Cellular Respiration • Identify major stages of the process • Location of each stage • Describe structures • Illustrate with simple diagrams • Indicate how ingredients are acquired/products released • Factors that affect the rate of respiration

  2. The stages • Group learning: what is respiration? General information & description. • Become an expert on one part of the process • Educate your group members • Collaborate and sync up the entire process • Make connections & compare • The BIG picture! Connect with photosynthesis The Processes Anaerobic respiration: Compare energy efficiency with aerobic respiration Glycolysis Krebs Cycle (aka Citric Acid Cycle) Electron Transport Chain Factors that affect the rate of respiration

  3. Resources • Online text & animations • Class notes linked to Mrs. DeNicola’s website • Animations on “AP Bio Links” page • Chapter 7 Review questions • Energy packets

  4. Making Energy: Cellular Respiration

  5. Where we last left off: **Glucose made as a byproduct of photosynthetic reactions • Harvesting stored energy… • Energy stored in organic molecules • carbohydrates, fats, proteins • Heterotrophs eat food • digestive results… • raw materials for synthesis • fuels for energy • controlled release of energy • “burning” fuels occurs inseries of step-by-step enzyme-controlled reactions

  6. glucose + oxygen  energy + water + carbon dioxide respiration + heat ATP + + 6CO2 6H2O  + C6H12O6 6O2 ATP glucose O2 • Glucose is the treasure chest • catabolizeglucose to produce ATP RESPIRATION = making ATP (& some heat)by burning fuels in many small steps ATP enzymes CO2 + H2O + ATP (+ heat)

  7. e p loses e- gains e- oxidized reduced + – + + H oxidation reduction H  + 6CO2 + + ATP C6H12O6 6O2 6H2O H How do we harvest energy from fuels? • Food digestion = bond breaking & electron movement (energy carrying) • Electron movement • NOT alone → move as part of H atom oxidation reduction e-

  8. O– O– O– O– P P P P –O –O –O –O O– O– O– O– O O O O NAD+ nicotinamide Vitamin B3 niacin O O H H C C NH2 C C NH2 N+ N+ reduction + H oxidation phosphates adenine ribose sugar Ele- Movement in Respiration • Electron carriers move ele-by shuttling H atoms • NAD+NADH (reduced) • FAD+2FADH2 (reduced) reducing power! NADH H carries electrons as a reduced molecule

  9. + ATP + + 6CO2 C6H12O6 6O2 6H2O Overview of cellular respiration • 4 metabolic stages • Anaerobic respiration (NOO2) 1. Glycolysis • in cytosol • Aerobic respiration (O2) • in mitochondria 2. Pyruvate oxidation 3. Krebs cycle 4. Electron transport chain (+ heat)

  10. glucose      pyruvate 6C 3C 2x 1. Glycolysis • “glyco – lysis” (splitting sugar) • Pathway observed in nearly ALL organisms • Speculated as one of oldest pathways, most fundamental • WHY? • Inefficient • For every 1 glucose generate only2 ATP That’s not enoughATP for me!

  11. enzyme enzyme enzyme enzyme enzyme enzyme enzyme ATP ATP 2 4 2 2 4 NAD+ ADP ADP 2Pi 2 2Pi 2H Overview glucose C-C-C-C-C-C 10 reactions • convert glucose (6C)to 2 pyruvate (3C) • produce:4 ATP & 2 NADH • consumes:2 ATP • NET YIELD: 2 ATP & 2 NADH fructose-1,6bP P-C-C-C-C-C-C-P G3P x2 C-C-C-P G3P x2 P~C-C-C-P Pyruvate x2 C-C-C G3P = glyceraldehyde-3-phosphate

  12. Feedback control • Why use excess when its not needed? • [ATP] activates/inactivates control enzyme (phosphofructokinase) • Enzyme used to make phosphorylated glucose • Allosteric regulation!!! • 2 active sites • 1. forms phosphorylated glucose • 2. conformation change  inactivate

  13. Is this enough to support life? O2 O2 O2 O2 O2 • Not a lot of energy… • for 1 billon years+ life on Earth survived this way • no O2 = slow growth, slow reproduction • only harvest 3.5% of energy stored in glucose • more carbons to strip off = more energy to harvest O2present Onto the Krebs Cycle!!!

  14. Onward Mito!

  15. outer membrane intermembrane space inner membrane cristae matrix mitochondrialDNA MitochondriaLStructure Review • Double membrane • smooth outer membrane • highly folded inner membrane • cristae • intermembrane space • fluid-filled between membranes • matrix • inner fluid-filled space • DNA, ribosomes • enzymes • free in matrix & membrane-bound

  16. Prepping for Krebs: formation of Acetyl CoA NAD+ 2 x [ ] reduction Acetyl CoA Coenzyme A CO2 Pyruvate C-C C-C-C oxidation Yield = 2C sugar + NADH + CO2 (Acetyl CoA)

  17. 1937 | 1953 2. Krebs cycle • aka Citric Acid Cycle • in mitochondrial matrix • 8 step pathway • each catalyzed by specific enzyme • step-wise catabolism of 6C citratemolecule (stripping out the carbons) • Appeared later than glycolysis – WHY? Hans Krebs 1900-1981

  18. 2C 6C 5C 4C 3C 4C 4C 4C 4C 6C CO2 CO2 Count the carbons! pyruvate acetyl CoA citrate oxidationof sugars This happens twice for each glucose molecule **Process regulated by + and – feedback control by [ATP]!!!** x2

  19. 2C 6C 5C 4C 3C 4C 6C 4C 4C 4C NADH ATP CO2 CO2 NADH FADH2 NADH Count the electron carriers! pyruvate acetyl CoA citrate reductionof electroncarriers This happens twice for each glucose molecule x2

  20. How’s our savings? • Fully oxidized • C6H12O6 •  • CO2 • NET YIELD:(3 NADH) x 2(1 ATP) x 2(1 FADH2) x 2 • 6 NADH • 2 ATP • 2 FADH2

  21. Let’s Recap… • Glycolysis2ATP • Kreb’s cycle 2ATP • Life takes a lot of energy to run, need to extract more energy than 4 ATP! • Fun Fact!!! I need a lotmore ATP! A working muscle recycles over 10 million ATPs per second

  22. 3. The ETC!!! • Proteins built into inner mitochondrial membrane • along cristae • transport proteins& enzymes • In presence of O2 • Ele- shuttled (by NADH & FADH2)down ETC pump H+ to create H+ gradient → chemiosmosis!!! • yields ~36 ATP from 1 glucose!

  23. Innermitochondrialmembrane The Players… Intermembrane space C Q Enzyme Enzyme Enzyme Mitochondrial matrix Cytochromes used for making H+ gradient

  24. e p 1 2 Let’s Follow the Chain… Building proton gradient! NADH  NAD+ + H intermembranespace H+ H+ H+ innermitochondrialmembrane H  e- + H+ C e– Q e– H e– FADH2 FAD H NADH 2H+ + O2 H2O NAD+ Enzyme Enzyme Enzyme mitochondrialmatrix What powers the proton (H+) pumps?…

  25. Electrons Flow Downhill • Ele-move in steps from carrier to carrier downhill to oxygen • each carrier more electronegative • controlled oxidation • controlled release of energy

  26. H+ H+ H+ H+ H+ H+ H+ H+ ADP + Pi H+ So, What’s the point?? • Set up H+ gradient • Allow protonsto flow through ATP synthase • Synthesize ATP ADP + PiATP CHEMIOSMOSIS!!!

  27. Energy Conversion **The Rules: NADH = 3 ATP FADH2 = 2 ATP • Glycolysis – 2 NADH • Conversion to – 2 NADHAcetyl CoA • Krebs cycle - 6 NADH 2 FADH2 • ETC 6 ATP 6 ATP 18 ATP + 4 ATP = 22 ATP 34 ATP!!!

  28. ~38 ATP Summing it up! + + 2 ATP 2 ATP ~34 ATP

  29. proteins    amino acids H | —C— | H hydrolysis C—OH N glycolysis Krebs cycle waste H O R || Beyond Sugars… 2C sugar = carbon skeleton = enters glycolysis or Krebs cycle amino group = Waste, excreted as ammonia, urea, or uric acid

  30. fats    glycerol + fatty acids hydrolysis glycerol (3C)  G3P  glycolysis fatty acids 2C acetyl acetyl Krebs groups coA cycle 2C fatty acids 3C glycerol enters glycolysis as G3P enter Krebs cycle as acetyl CoA

  31. Energy from All avenues! • Digestion • carbohydrates, fats & proteins • all catabolized through same pathways • enter at different points • cell extracts energy from every source

  32. Why waste? Enough energy? Build stuff!!! pyruvate glucose Krebs cycleintermediaries amino acids   acetyl CoA  fatty acids • points in glycolysis & Krebs cycle used as link to pathways for synthesis • run pathways “backwards” • have extra fuel, build fat!

  33. What happens the absence of oxygen? O2 O2 Pyruvate anaerobicrespirationfermentation aerobic respirationmitochondria Krebs cycle

  34. Alcohol Fermentation • Dead end process • ~12% ethanol, kills cells • can’t reverse reaction

  35. Lactic Acid Fermentation • Reversible process • if O2becomes available, lactate converted to pyruvate by the liver

  36. recycleNADH Anaerobic Fermenation: WhaT’s the Point???

  37. pyruvate ethanol + CO2 3C 2C 1C pyruvate lactic acid NADH NADH NAD+ NAD+ 3C 3C Commercial Uses… • Bacteria, yeast • Animals, some fungi back to glycolysis • beer, wine, bread back to glycolysis • cheese, anaerobic exercise (no O2)

  38. Review Animations • Cell Respiration with Hank • ETC • ATP Synthase

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