Processes Cheat Sheet-2 PDF

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Metabolic processes cheat sheet...

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Cellular Respiration a. Overall goal: to make energy (ATP) b. C6H12O6 + 6O2  6CO2 + 6H2O + energy c. If oxygen is present, it is composed of three parts: glycolysis or fermentation, krebs cycle, and electron transport chain 1. Glycolysis a. Oxidizes glucose to pyruvate b. Multistep reaction; energy input required for some steps, but there is a net release of energy i. Energy released is used to reduce NAD+ and synthesize ATP by substrate-level phosphorylation ii. Substrate-level phosphorylation – the use of chemical energy (usually from G3P) to add the third phosphate on to ADP. It is an enzyme-catalyzed transfer. d. Occurs in the cytosol of all organisms e. The major step you need to know i. Phosphofructokinase is the enzyme responsible for the transformation of fructose-6phosphate into fructose-1,6-bisphosphate 1. 2 ATP used, bind to active site 2. Monitored via feedback inhibition a. When there is too much product (ATP), the product will inhibit the reaction from occurring b. ATP will bind to the regulatory site, altering the conformation of phosphofructokinase, slowing down glycolysis. f. Numbers: i. Net 1. Put in 1 glucose, 2 ADP, 2 phosphates, 2 NAD+ 2. Get out 2 pyruvates, 2 H2O, 2 ATP, 2 NADH + 2H+ ii. You actually put in 4 ADP and 4 phosphates, but you also use 2 ATP for phosphofructokinase. Therefore, you cancel them both out g. The 2 NADH go to the Electron Transport Chain 2. Fermentation a. If no oxygen is present, then fermentation occurs (Anaerobic reaction) b. Occurs in the cytosol c. Provide NAD+ to re-charge glycolysis d. Lower energy yield (only 2 ATP per glucose) i. With aerobic reactions (regular cellular respiration), we get around 40 ATP per glucose e. Instead of the pyruvate moving on to the mitochondria, it moves on as an intermediate that accepts electrons from NADH, turning it back into NAD+. i. This allows the glycolysis process to keep reoccurring ii. The pyruvate goes on to form lactic acid (animals and bacteria) or ethanol (yeast) f. Numbers: i. Same as glycolysis 3. Pyruvate Processing a. Pyruvate is converted to acetyl CoA with the release of CO2 b. Coenzyme A is derived from a B vitamin c. One molecule of NADH is generated d. Steps i. Pyruvate enters the mitochondria via a transport protein ii. CO2 is released iii. NAD+ is reduced to NADH

iv. Coenzyme A is added v. Final product is acetyl CoA e. Numbers i. Goes in: 2 pyruvates (from glycolysis), 2 NAD+, 2 coenzyme A ii. Comes out: 2 CO2, 2 NADH + H+, 2 Acetyl CoA f. The 2 NADH are going to the Electron Transport Chain as carriers 4. Citric Acid Cycle (Krebs Cycle) a. Purpose: extract energy from pyruvate b. Occurs in mitochondrial matrix (eukaryotes) or cytosol (prokaryotes) c. Goes in: 2 pyruvate (now in the form of Acetyl CoA), 6 NAD+, 2 FAD, 2 ADP, 2 phosphates i. Substrate level phosphorylation occurs d. Comes out: 6 CO2, 6 NADH +H+, 2 FADH2, 2 ATP i. The NADH and the FADH2 all go to the Electron Transport Chain 5. Electron Transport Chain a. Takes place along the inner mitochondrial membrane (the membranes of the cristae) b. NADH and FADH2 (from glycolysis, pyruvate processing, and citric acid cycle) donate electrons c. Electrons are transferred along the chain i. Progressive decrease in free energy ii. Transport of electrons through complexes I, III, and IV is coupled to proton pumping iii. Creates proton gradient (more protons outside of the matrix then inside. The protons come inside the cell via a protein. This movement drives a motor, which provides the energy needed to add the third phosphate to ADP to make ATP iv. Oxidative phosphorylation d. Oxygen is the final electron acceptor e. Get out approximately 36 ATP Photosynthesis a. 6CO2 + 6 H2O + light -> C6H12O6 + 6O2 b. Occurs in chloroplasts (plants/algae) or plasma membrane and cytosol (some prokaryotes) c. Two sets of reactions i. Light reactions 1. Results in ATP, NADPH, and O2 ii. Calvin Cycle 1. Results in sugar 6. Light Reactions a. Takes place in the thylakoid b. Water is split, and the electrons are donated to PSI i. This is why oxygen is a product of photosynthesis as well c. Photons of light excite electrons from PSII chlorophylls d. Electrons jump around until they hit reaction center P680 e. Excited chlorophyll electrons are passed to primary electron acceptor Pheophytin f. Electrons accepted by Pheophytin are transferred to PQ and then passed down the electron transport chain to the cytochrome complex i. This creates ATP in the exact same way that the electron transport chain in cellular respiration creates ATP, only this time, it is called photophosphorylation g. PQ carries electrons from PSII, along with protons from the stroma h. The electrons are passed to the cytochrome complex i. The protons are released into the thylakoid lumen j. Electrons deposited in PSI

k. Photons of light excite electrons, and they jump around until they hit reaction center P700. l. Then the electrons pass through electron transport chain until they hit Ferredoxin m. Ferredoxin donates electrons to NADP+ to make NADPH i. NADPH will go to the Calvin Cycle Calvin Cycle a. Takes place in the stroma b. 3 CO2 enter, but only one at a time c. Carbon fixation ii. The addition of CO2 to the 5-carbon compound RuBP is catalyzed by the enzyme rubisco iii. Requires ATP 1. 2 ATP are used per cycle 2. 6 ATP used altogether (3 CO2 = 3 cycles) d. Reduction i. Addition of electrons from NADPH to generate 3-carbon sugars ii. Requires NADPH 1. 2 NADPH are used per cycle 2. 6 NADPH are used altogether iii. Results in the production of Glyceraldehyde-3-phosphate (G3P) 1. 2 per cycle 2. 6 in total iv. One of the G3Ps is going to go be used to make glucose and other organic compounds e. Regeneration of CO2 acceptor i. The other G3Ps are used to regenerate Ribulose bisphosphate (RuBP) ii. Requires ATP 1. 1 ATP per cycle 2. 3 ATP altogether f. Total cost i. Put in: 3 CO2, 9 ATP, 6 NADPH ii. Get out: 1 G3P, 9 ADP + Pi, 6 NADP+ + Pi...