Cellular Respiration & Photosynthesis Outline PDF

670df2c4aec86.doc Intro to Cellular Respiration & Photosynthesis, Ch. 6&7 Cellular Respiration is the key process of Metabolism Anabolism + catabolism = metabolism Breakdown of molecules (for energy) = catabolism Making new molecules (for building blocks) = anabolism Photosynthesis: CO2 +...

670df2c4aec86.doc Intro to Cellular Respiration & Photosynthesis, Ch. 6&7 Cellular Respiration is the key process of Metabolism Anabolism + catabolism = metabolism Breakdown of molecules (for energy) = catabolism Making new molecules (for building blocks) = anabolism Photosynthesis: CO2 + H20 glucose + O2 Cellular Respiration: glucose + O2 CO2 + H20 Cellular Respiration - uses Energy from glucose to make ATP - Releases energy in chemical bonds of glucose, makes it accessible to cell as ATP Why not just use the glucose directly?  Glucose has far more energy per molecule than needed.  ATP is a more convenient E source, has smaller amount of E per molecule 1  670df2c4aec86.doc The Big Picture! Cellular respiration involves three major processes 1. Glycolysis in cytoplasm  starts breaking down glucose & makes products needed for next two processes  breaks glucose (6C) into two pyruvate/pyruvic acid (3C) molecules >“Pre-Krebs” or Pyruvate Oxidation < - molecules move into mitochondria - preps pyruvate for next step 2. Krebs cycle (Citric acid cycle) in mitochondria  stores E from glucose in carrier molecules  produces large numbers of carrier molecules (NADH & FADH2) 3. Electron Transport Chain & Chemiosmosis (= Oxidative Phosphorylation) in mitochondria uses carrier molecules to produce lots of ATP 2  670df2c4aec86.doc Glycolysis (~9-10 reactions) Net yield (per glucose): 2 ATP 2 NADH Pre-Krebs step (Pyruvate Oxidation) - the 2 pyruvate (pyruvic acid) enter mitochondria - the 2 NADH enter mitochondria (this uses 2 ATP) - converts pyruvate (pyruvic acid) to acetylCoA Net yield (per glucose): -2 ATP 2 NADH Krebs Cycle (citric acid cycle) The molecules involved in this cycle are regenerated, and can go back into the cycle again. Net yield (per glucose): 2 ATP 6 NADH 2 FADH2 3  670df2c4aec86.doc also 4 CO2 By end of Krebs Cycle, glucose is completely broken down:  all 6 C have been released as carbon dioxide  all 12 H’s have been put onto carriers (NADH, FADH2) Total so far: Glycolysis 2 ATP 2 NADH Pre-Krebs -2 ATP 2 NADH Krebs 2 ATP 6 NADH 2 FADH2 Total 2 ATP 10 NADH 2 FADH2 Electron Transport Chain  Occurs in the mitochondria  NADH in the matrix goes to the first protein complex  NADH releases e- (and H+)  NAD+  Electron is passed from one protein complex to another, losing Energy with each step  This Energy is used to pump H+ (through membrane) into the intermembrane space.  At the end, electrons are combined with 2H+ and ½ O2 to form water Oxygen is the final electron acceptor  H+ build up in the intermembrane space concentration gradient 4 670df2c4aec86.doc 5  670df2c4aec86.doc Chemiosmosis  H+ Flow back into the matrix through ATP synthase  The Energy from the H flow is used to turn ADP back to ATP each NADH produces 3 ATP each FADH2 produces 2 ATP (starts farther along the chain, at lower E) Electron Transport & Chemiosmosis: 10 NADH x 3 ATP = 30 ATP 2 FADH2 x 2 ATP = 4 ATP = 34 ATP Final Overall Tally: 36 ATP for each glucose molecule → You need O2 for this process, because it’s highly electronegative 6