Division Ave. High School AP Biology

Transcription

1 Overview 10 reactions u convert () to pyruvate (3C) u produces: 4 & NADH u consumes: u net: & NADH C-C-C-C-C-C fructose-1,6bp P-C-C-C-C-C-C-P DHAP P-C-C-C G3P C-C-C-P H P i P i pyruvate C-C-C 4 4 NAD + Cellular Respiration Stage & 3: Oxidation of Pyruvate Krebs Cycle Glycolysis is only the start Glycolysis pyruvate x 3C Pyruvate has more energy to yield u 3 more C to strip off (to oxidize) u if O is available, pyruvate enters mitochondria u enzymes of Krebs cycle complete the full oxidation of sugar to pyruvate 3C 1C 1

2 Cellular respiration Mitochondria Structure Double membrane energy harvesting organelle u smooth outer membrane u highly folded inner membrane cristae u intermembrane space fluid-filled space between membranes u matrix inner fluid-filled space u DNA, ribosomes u enzymes outer intermembrane space inner membrane free in matrix & membrane-bound cristae membrane matrix What cells would have AP a lot Biology of mitochondria? mitochondrial DNA Mitochondria Function Dividing mitochondria Who else divides like that? bacteria! Oooooh! Form fits function! Membrane-bound proteins Enzymes & permeases What does this tell us about the evolution of eukaryotes? Endosymbiosis! Advantage of highly folded inner membrane? More surface area for membranebound enzymes & permeases

3 Oxidation of pyruvate Pyruvate enters mitochondrial matrix [ ] x pyruvate acetyl CoA + 3C C 1C NAD u 3 step oxidation process u releases (count the carbons!) u reduces NAD NADH (moves e - ) u produces acetyl CoA Acetyl CoA enters Krebs cycle Where does the go? Exhale! Pyruvate oxidized to Acetyl CoA NAD + reduction Pyruvate C-C-C Coenzyme A oxidation Acetyl CoA C-C x [ Yield = C sugar + NAD ] Krebs cycle aka Citric Acid Cycle u in mitochondrial matrix u 8 step pathway Hans Krebs each catalyzed by specific enzyme step-wise catabolism of citrate molecule Evolved later than glycolysis u does that make evolutionary sense? bacteria 3.5 billion years ago (glycolysis) free O.7 billion years ago (photosynthesis) eukaryotes 1.5 billion years ago (aerobic respiration = organelles mitochondria) 3

4 Count the carbons! pyruvate 3C C acetyl CoA citrate This happens twice for each molecule oxidation of sugars x 5C Count the electron carriers! pyruvate 3C C NADH acetyl CoA citrate NADH This happens twice for each molecule reduction of electron carriers x 5C NADH FADH NADH Whassup? So we fully oxidized C 6 H 1 O 6 & ended up with 4! What s the point? 4

5 Electron Carriers = Hydrogen Carriers Krebs cycle produces large quantities of electron carriers u NADH u FADH u go to Electron Transport Chain! + Pi H+ H+ What s so important about electron carriers? Energy accounting of Krebs cycle 4 NAD + 1 FAD 4 NAD 1 FADH x pyruvate 3C 3x 1C 1 1 Net gain = = 8 NAD FADH Value of Krebs cycle? If the yield is only then how was the Krebs cycle an adaptation? u value of NADH & FADH electron carriers & H carriers w reduced molecules move electrons w reduced molecules move ions to be used in the Electron Transport Chain like $$ in the bank 5

6 What s the point? The point is to make! And how do we do that? synthase u set up a gradient u allow to flow through synthase u powers bonding of P i to + P + P i But Have we done that yet? NO! The final chapter to my story is next! Any Questions?