2. AP Biology 2009- 2010 Cellular Respiration Harvesting Chemical Energy ATP

3. AP Biology Energy needs of life  Animals are energy consumers  What do we need energy for?  synthesis (building for growth)  reproduction  active transport  movement  temperature control (making heat)

4. AP Biology Where do we get energy?  Energy is stored in organic molecules  carbohydrates, fats, proteins  Animals eat these organic molecules  food  digest food to get  fuels for energy (ATP)  raw materials for building more molecules  carbohydrates, fats, proteins, nucleic acids ATP

5. AP Biology CO 2 + H 2 O + heat fuel (carbohydrates) O2O2 “Burn fuels” to make energy combustion making heat energy by burning fuels in one step ATP ATP + CO 2 + H 2 O (+ heat) aerobic respiration making ATP energy (& some heat) by burning fuels in many small steps food (carbohydrates) O2O2 Unusable energy – too much of it Usable energy due to the many smaller steps

6. AP Biology 2009- 2010 ATP What is energy in biology? Whoa! HOT stuff! Adenosine TriPhosphate

7. AP Biology Harvesting energy stored in food  Cellular respiration  breaking down food to produce ATP  in mitochondria  using oxygen  “aerobic” respiration  usually digesting glucose  but could be other sugars, fats, or proteins C 6 H 12 O 6 6O 2 ATP6CO 2 6H 2 O  + ++ glucose + oxygen  energy + carbon + water dioxide O2O2 food ATP

8. AP Biology How do we move electrons in biology?  Moving electrons in living systems  electrons cannot move alone in cells  electrons move as part of H atom via redox reactions (oxidation-reduction reactions)  move H = move electrons + H + H +– loses e-gains e-oxidizedreduced oxidationreduction C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP  +++ oxidation reduction H e-e- The reduced form of a molecule has a higher energy state than the oxidized form

9. AP Biology Oxidation & reduction  Oxidation  removing H  loss of electrons  releases energy  exergonic  Reduction  adding H  gain of electrons  stores energy  endergonic C 6 H 12 O 6 6O 2 6CO 2 6H 2 OATP  +++ oxidation reduction Oil Rig: Oxidizing is losing electrons, reducing is gaining electrons

10. AP Biology Moving electrons in respiration  Electrons do not move directly from glucose to oxygen  Electron carriers move electrons by shuttling H atoms around  NAD + (nicotinamide adenine dinucleotide)  NADH (reduced)  FAD +2 (Flavin adenine dinucleotide)  FADH 2 (reduced) + H reduction oxidation P O–O– O–O– O –O–O P O–O– O–O– O –O–O C C O NH 2 N+N+ H adenine ribose sugar phosphates NAD + nicotinamide Vitamin B3 niacin P O–O– O–O– O –O–O P O–O– O–O– O –O–O C C O NH 2 N+N+ H NAD H carries electrons as a reduced molecule H

11. AP Biology Overview of cellular respiration  3 metabolic stages  Anaerobic respiration 1. Glycolysis  respiration without O 2  in cytosol  Aerobic respiration  respiration using O 2  in mitochondria 2. Krebs cycle 3. Electron transport chain and chemiosmosis C 6 H 12 O 6 6O 2 ATP6H 2 O6CO 2  +++ (+ heat )

12. AP Biology Glycolysis glucose      pyruvate 2x2x 6C3C In the cytosol? Why does that make evolutionary sense? That’s not enough ATP for me!  Breaking down glucose  “glyco – lysis” (splitting sugar)  ancient pathway which harvests energy  where energy transfer first evolved  transfer energy from organic molecules to ATP  starting point for ALL cellular respiration  but it’s inefficient  generate only 2 ATP for every 1 glucose  occurs in cytosol

13. AP Biology Evolutionary perspective  Prokaryotes  first cells had no organelles  Anaerobic atmosphere  life on Earth first evolved without free oxygen (O 2 ) in atmosphere  energy had to be captured from organic molecules in absence of O 2  Prokaryotes that evolved glycolysis are ancestors of all modern life  ALL cells still utilize glycolysis

14. AP Biology Pyruvate is a branching point Pyruvate O2O2 O2O2 mitochondria Krebs cycle aerobic respiration fermentation anaerobic respiration

15. AP Biology Fermentation (anaerobic)  Bacteria, yeast 1C 3C2C pyruvate  ethanol + CO 2  Animals, some fungi pyruvate  lactic acid 3C  beer, wine, bread  anaerobic exercise (no O 2 ) NADHNAD + NADHNAD + back to glycolysis 

16. AP Biology  Krebs cycle produces large quantities of electron carriers  NADH  FADH 2  go to Electron Transport Chain! Electron Carriers = Hydrogen Carriers Glucose is completely Oxidized to CO2 ATP ADP + P i

17. AP Biology Electron Transport Chain intermembrane space mitochondrial matrix inner mitochondrial membrane NAD + Q C NADH H 2 O H+H+ e–e– 2H + +O2O2 H+H+ H+H+ e–e– FADH 2 1212 NADH dehydrogenase cytochrome bc complex cytochrome c oxidase complex FAD e–e– H H  e- + H + NADH  NAD + + H H p e Building proton gradient! Creates a proton gradient!

18. AP Biology  ATP synthase enzyme  H + flows through it  conformational changes  bond P i to ADP to make ATP  The ETC’s H + gradient  allows the H + to flow down concentration gradient through ATP synthase  ADP + P i  ATP H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP ADP P + And how do we make ATP?