Cellular Respiration The breakdown of glucose for cellular energy. happens in all living cells. is exothermic H atoms and e are removed from glucose (oxidization) and added to oxygen (reduction) excess energy (40% the rest is waste) is used to synthesize, an endothermic reaction
Cellular Respiration 1 C6 Glycolysis "breaking sugar" anaerobic (no O 2 ) cytoplasm or Fermentation anaerobic cytoplasm Aerobic Cellular Respiration 2 C 3 Lactic Acid Fermentation or Alcohol Fermentation aerobic (requires O 2) mitochondria C 3 C 2 2 3 Transition Reaction Krebs Cycle 4 Electron Transport Chain http://www.youtube.com/watch?v=rgap9ne8d9k&feature=related
1 Glycolysis happens in the cytoplasm of all cells 1 Glucose 2 pyruvate + 2 6 carbons 3 carbons + Glucose
1 Glycolysis 6C 3C 3C 3C Pyruvate 3C Pyruvate Glycolysis I endothermic activation requires 2 breaks glucose into 2 molecules -2 + 4 = 2 Glycolysis II exothermic reactions each 3 carbon molecule generates 2, as it is turned into pyruvate, for a total of 4 produced http://www.youtube.com/watch?v=3gtjqtquuow
6C 1 Glycolysis 3C 3C 3C Pyruvate 3C Pyruvate now what? 3 possibilities, depending on the type of cell and conditions Aerobic Cellular 2 Respiration 2 Fermentation Anaerobic Respiration Pyruvate moves into mitochondria of eukaryotic cells if sufficient O 2 is present Alcohol Fermentation prokaryotic cells e.g. yeast produces 2 ethanol, 2 (from glycolysis) and 2 CO 2 **Both types of fermentation provide means to allow glycolysis to continue, by restoring. Lactic Acid Fermentation eukaryotic cells lacking O 2, bacteria, fungi produces 2 lactic acid and 2 (from glycolysis)
Cellular Respiration April 25, 2012 Aerobic Cellular Respiration If there is sufficient O2 in a eukaryotic cell, the pyruvate will move into the mitochondrion for further breakdown. Remember the mitochondrion??? intermembrane space [H]+ ion reservoir (enzyme rich fluid)
2 Transition Reaction Matrix A transport protein moves the pyruvate into the matrix of the mitochondria Pyruvate oxidation occurs in the matrix 3C Pyruvate + 2C Acetyl CoA CO 2 Pyruvate is oxidized to form Acetyl Co A, which will enter the Kreb s Cycle CO 2 is produced
3 in the matrix... Krebs Cycle (Citric Acid Cycle) 2C Acetyl CoA 6C (citrate) 6C For every Acetyl CoA: 3 1 FADH 2 1 remember x2! H 2 O FADH 2 FAD CO 2 CO 2 5C At this point, where have the 6C from glucose gone? and FADH 2 carry electrons forward to the next step... Krebs Cycle http://www.youtube.com/watch?v=hw5nwb0xn0y&feature=related
4 Electron Transport Chain Wait...what can possibly happen here? Glucose has been totally catabolized into CO 2. Notice we haven't used any O 2 yet? and what are all those and FADH 2 for...wasn't the point to make????
Let's look at what we have so far: 1 Glycolysis 2 3 CO 2 2 Transition Reaction 2 Krebs Cycle 2 6 2 FADH 2 6C 3C Pyruvate H2O FADH 2 FAD 2C 3C 3C + Acetyl CoA 6C (citrate) CO 2 2 6C 5C 3C Pyruvate 3C Pyruvate 2C Acetyl CoA CO 2 x2 x2 Total = 4 Total = 10 Total FADH 2 = 2
Recall: Phosphorylation The addition of one or more phosphate groups to a molecule. + Pi + H2O Cycle http://www.youtube.com/watch?v=lx9gklk0xqg
Chemiosmosis Formation of molecules through the movement of hydrogen ions across and electrochemical gradient. (p. 64 65) Concentration gradient involving H + or e phosophorylation http://www.youtube.com/watch?v=vyekdkbyb8y Gradients http://www.youtube.com/watch?v=_97mna_kkds&feature=related
4 The Electron Transport Chain Occurs in the inner membrane of the mitochondria cristae Proteins embedded in the membrane help to move hydrogen ions and FADH 2 (energy rich electron donors) provide the electrons required Bring electrons and H+ ions from the Kreb s cycle in the matrix to the electron transport chain in the cristae Electrons and H+ ions are removed from and FADH 2
The electron transport chain involves a series of proteins, which are embedded in the inner membrane (cristae) of the mitochondria that help to pump protons across the membrane These 4 large proteins are referred to as Complexes I IV p.75
Cellular Respiration April 25, 2012 Electrons move through the chain in a series of oxidation and reduction reactions The small amounts of energy released power the proton pumps The complexes pump H+ ions from the matrix into the intermembrane space This causes the concentration of H+ ions to build up in the intermembrane space, creating a concentration gradient between the intermembrane space and the matrix ETC http://www.youtube.com/watch?v=0lcwbkow0u8
In the final steps: Oxygen is the final acceptor for electrons, and combines with hydrogen to become water H+ ions are allowed to move down the concentration gradient, through another complex called Synthase, back into the matrix is produced from by the process of phosphorylation http://www.youtube.com/watch?v=zemulstire8 http://www.youtube.com/watch?v=_97mna_kkds&feature=related
In the cytoplasm: glycolysis Totals 2 2 In the mitochondria: from glycolysis: from respiration: pyruvate Acetyl CoA: krebs cycle: 2 1 3 1 FADH 2 4 3 1 9 2 x2 x2 4 6 24 36
Glucose 2 Pyruvate 2 CO 2 6 H 2 O 4 CO 2