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Regents Biology 2009-2010 Cellular Respiration Harvesting Chemical Energy.

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Presentation on theme: "Regents Biology 2009-2010 Cellular Respiration Harvesting Chemical Energy."— Presentation transcript:

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2 Regents Biology Cellular Respiration Harvesting Chemical Energy

3 Regents Biology ATP What is energy in biology? Adenosine TriPhosphate

4 Regents 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

5 Regents Biology What do we need to make energy?  The “Furnace” for making energy  mitochondria  Fuel  food: carbohydrates, fats, proteins  Helpers  oxygen  enzymes  Product  ATP  Waste products  carbon dioxide  then used by plants  water O2O2 food ATP enzymes CO 2 H2OH2O

6 Regents Biology Can’t store ATP  too unstable  only used in cell that produces it  only short term energy storage  carbohydrates & fats are long term energy storage Using ATP to do work? A working muscle recycles over 10 million ATPs per second ATP ADP work Adenosine DiPhosphate Adenosine TriPhosphate

7 Regents Biology Glycolysis glucose      pyruvate 2x2x 6C3C  Breaking down glucose  “glyco – lysis” (splitting sugar)  ancient pathway which harvests energy  where energy transfer first evolved  transfer energy from organic molecules to ATP  still is starting point for ALL cellular respiration  but it’s inefficient  generate only 2 ATP for every 1 glucose  occurs in cytosol

8 Regents 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

9 Regents Biology 10 reactions  convert glucose (6C) to 2 pyruvate (3C)  produces: 4 ATP & 2 NADH  consumes: 2 ATP  net yield: 2 ATP & 2 NADH glucose C-C-C-C-C-C fructose-1,6bP P-C-C-C-C-C-C-P 2 G3P C-C-C-P pyruvate C-C-C Overview ATP 2 ADP 2 ATP 4 ADP 4 NAD + 2 enzyme 2e-2e- 2

10 Regents Biology Pyruvate is a branching point Pyruvate O2O2 O2O2 mitochondria Krebs cycle aerobic respiration fermentation

11 Regents Biology pyruvate       CO 2 Glycolysis is only the start  Glycolysis  Pyruvate has more energy to yield  More e - to remove  if O 2 is available, pyruvate enters mitochondria  enzymes of Krebs cycle complete the full breakdown of sugar to CO 2 2x2x 6C3C glucose      pyruvate 3C1C

12 Regents Biology Cellular respiration

13 Regents Biology intermembrane space inner membrane outer membrane matrix cristae Mitochondria — Structure  Double membrane energy harvesting organelle  smooth outer membrane  highly folded inner membrane  cristae  intermembrane space  fluid-filled space between membranes  matrix  inner fluid-filled space  DNA, ribosomes  enzymes  free in matrix & membrane-bound mitochondrial DNA

14 Regents Biology pyruvate    acetyl CoA + CO 2 Production of Acetyl CoA NAD 3C2C 1C [ 2x ]  Pyruvate enters mitochondrial matrix  3 step process  releases 2 CO 2 (count the carbons!)  reduces 2 NAD  2 NADH (moves e - )  produces 2 acetyl CoA  Acetyl CoA enters Krebs cycle

15 Regents Biology Pyruvate converted to Acetyl CoA Yield = 2C sugar + NADH + CO 2 reduction oxidation Coenzyme A Pyruvate Acetyl CoA C-C-C C-C CO 2 NAD + 2 x []

16 Regents Biology Krebs cycle  aka Citric Acid Cycle  in mitochondrial matrix  8 step pathway  each catalyzed by specific enzyme  step-wise catabolism of 6C citrate molecule  Evolved later than glycolysis  does that make evolutionary sense?  bacteria  3.5 billion years ago (glycolysis)  free O 2  2.7 billion years ago (photosynthesis)  eukaryotes  1.5 billion years ago (aerobic respiration = organelles  mitochondria) 1937 | 1953 Hans Krebs

17 Regents Biology 4C6C4C 2C6C5C4C CO 2 citrate acetyl CoA Count the carbons! 3C pyruvate x2x2 breakdown of sugars This happens twice for each glucose molecule

18 Regents Biology 4C6C4C 2C6C5C4C CO 2 citrate acetyl CoA Count the electron carriers! 3C pyruvate production of electron carriers This happens twice for each glucose molecule x2x2 CO 2 NADH FADH 2 ATP

19 Regents Biology  Krebs cycle produces large quantities of electron carriers  NADH  FADH 2  go to Electron Transport Chain! Electron Carriers H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP ADP + P i

20 Regents Biology Energy accounting of Krebs cycle Net gain=2 ATP =8 NADH + 2 FADH 2 1 ADP1 ATP ATP 2x 4 NAD + 1 FAD4 NADH + 1 FADH 2 pyruvate          CO 2 3C 3x3x 1C

21 Regents Biology ATP accounting so far…  Glycolysis  2 ATP  Kreb’s cycle  2 ATP  Life takes a lot of energy to run, need to extract more energy than 4 ATP! A working muscle recycles over 10 million ATPs per second There’s got to be a better way! I need a lot more ATP!

22 Regents Biology There is a better way!  Electron Transport Chain  series of proteins built into inner mitochondrial membrane  along cristae  transport proteins & enzymes  transport of electrons down ETC linked to pumping of H + to create H + gradient  yields ~38 ATP from 1 glucose!  only in presence of O 2 (aerobic respiration) O2O2

23 Regents Biology Mitochondria  Double membrane  outer membrane  inner membrane  highly folded cristae  enzymes & transport proteins  intermembrane space  fluid-filled space between membranes

24 Regents 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 FAD e–e– H H  e- + H + NADH  NAD + + H H p e Building proton gradient! What powers the proton (H + ) pumps?…

25 Regents Biology But what “pulls” the electrons down the ETC? O2O2 H2OH2O

26 Regents Biology Electrons flow downhill  Electrons move in steps from carrier to carrier downhill to oxygen  each carrier more electronegative  controlled oxidation  controlled release of energy

27 Regents Biology H+H+ ADP + P i H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ We did it! ATP  Set up a H + gradient  Allow the protons to flow through ATP synthase  Synthesizes ATP ADP + P i  ATP “proton-motive” force

28 Regents Biology  The diffusion of ions across a membrane  build up of concentration gradient just so H+ could flow through ATP synthase enzyme to build ATP Chemiosmosis Chemiosmosis links the Electron Transport Chain to ATP synthesis

29 Regents Biology Cellular respiration 2 ATP ~34 ATP ++ ~38 ATP

30 Regents Biology What if oxygen is missing?  No oxygen available = can’t complete aerobic respiration  Fermentation  alcohol fermentation  lactic acid fermentation  no oxygen or no mitochondria (bacteria)  Anaerobic process  can only make very little ATP  large animals cannot survive O2O2 yeast bacteria

31 Regents Biology Fermentation  alcohol fermentation  yeast  glucose  ATP + CO 2 + alcohol  make beer, wine, bread  lactic acid fermentation  bacteria, animals  glucose  ATP + lactic acid  bacteria make yogurt  animals feel muscle fatigue O2O2


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