BIO 100 Chapter 7 notes
BIO 100 Chapter 7 notes BIO 100
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This 3 page Class Notes was uploaded by Lauren Tebbe on Wednesday September 28, 2016. The Class Notes belongs to BIO 100 at Eastern Kentucky University taught by Kenneth Blank in Fall 2016. Since its upload, it has received 6 views.
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Date Created: 09/28/16
Chapter 7 BIO notes 1 Cellular Respiration o ATP molecules are produced by cellular respiration which is a process that requires the participation of mitochondria. o Take in oxygen, gives off carbon dioxide o Oxidation of substrates is a fundamental part of cellular respiration; cellular respiration is a redox reaction in this case releases energy then used by cell. o Cellular respiration is the reverse of photosynthesis 2 Phases of Complete Glucose Breakdown o Glucose is broken down slowly as controlled by cells making bonds more efficiently captured and making ATP molecules o The enzyme that carries out oxidation during cellular respiration are assisted by nonprotein helpers called coenzymes o 4 Phases to cellular respiration where carbon dioxide and water are produced: 1. Glycolysis - occurs in cytoplasm, breakdown glucose into 2 molecules of pyruvate, 2 ATP are gained and oxidation results in NADH 2. Preparatory Reaction - takes place in matrix of mitochondria, Pyruvate broken down into 2 carbon acetyl groups carried by coenzyme, results in NADH and CO2 3. Citric Acid Cycle - takes place in mitochondria matrix, NADH and FADH2 result and CO2 is released, produce 2 ATP per glucose molecule 4. Electron transport chain - in cristae mitochondria, NADH and FADH2 give up electron to the chain, energy is released and captured moving from higher to lower energy state, produces water 2 Outside of Mitochondria: Glycolysis o Takes place here in eukaryotic cells within the cytoplasm o During Glycolysis, glucose is broken down to 2 molecules of pyruvate. o It is divided into the energy investment step when some ATP is used to begin the reactions and the energy harvesting steps when both NADPH and ATP are produced 3 Energy-Investment Step o During this, 2 ATP transfer phosphate groups to substrates and two ADP+P result 4 Energy-Harvesting Steps o During this, electrons and hydrogen ions are removed from the substrates and captured by NAD+ producing NADH. o Energized phosphate groups are used to synthesize 4 ATP by a process called substrate level ATP synthesis which basically involves a transfer of a phosphate group from the intermediate molecule to ADP forming ATP o If oxygen is present, the end product is used to generate more ATP. If oxygen is not available, goes to fermentation pathways 5 Outside of the Mitochondria: Fermentation o Oxygen is required for the complete breakdown of glucose o Fermentation, is the anaerobic breakdown of glucose, resulting in the production of 2 ATP per glucose, ensures that ATP is available for cellular processes o Why is it beneficial for pyruvate to be reduced to lactate when oxygen is not available? The reaction regenerates NAD+ which can pick up more electrons during the earlier reactions of glycolysis. 6 Microorganisms and Fermentation o Yeast is a good example of microorganisms generating ethyl alcohol and CO2 when they carry out fermentation. 7 Inside the Mitochondria o If oxygen is present following glycolysis, the cell will enter the aerobic phases of cellular respiration and these reactions occur inside the mitochondria 8 Preparatory Reaction o This reaction produces a substrate that can enter the citric acid cycle o Glycolysis produces 2 pyruvate molecules so the preparatory reactions occurs twice per glucose molecule o During this reaction, pyruvate is oxidized and CO2 is given off, NAD+ accepts electrons and hydrogen ions forming NADH, and the product forms acetyl-CoA 9 The Citric Acid Cycle o This is a cyclical metabolic pathway located in the matrix of mitochondria o At the start, 2 carbon acetyl group carried by CoA join with a 4 carbon molecule producing 6 carbon citrate molecule. CoA returns to the preparatory stage o During the cycle, acetyl group is oxidized, both NAD+ and FAD accept electrons and hydrogen ions, substrate level ATP synthesis occurs 10 The Electron Transport Chain o This is located in the cristae of mitochondria and is a series of carriers that pass electrons from one to the other. o The electron transport chain is a series of redox reactions that remove the high energy electrons from NADH and FADH2 o The role of oxygen in cellular respiration is to act as the final acceptor of electrons in the electron transport chain o Once NADH has delivered electrons to the electron transport chain, NAD+ is regenerated and can be used again, same with FAD 11 Generating ATP o The complexes use the energy released by oxidation reduction to pump H+ from the mitochondrial matrix into the intermembrane space located between the outer and inner membranes of mitochondrion o The H+ gradient contains a large amount of stored energy that can be used to drive forward ATP synthesis. o The cristae mitochondria contain an ATP synthase complex that allows H+ to return to the matrix 12 Metabolic Fate of Food o Energy Yield from Glucose o Per glucose, there is a net gain of 2 ATP from glycolysis which takes place in the cytoplasm o Most of the ATP produced comes from the electron transport chain and the ATP synthase complex 13 Alternative Metabolic Pathways o When fat is used as an energy source, its break down to glycerol and three fatty acid chains, because glycerol is a carbohydrate it enters the process of cellular respiration during glycolysis o The complete breakdown of glycerol and fatty acids results in many more ATP per fat molecule than does the breakdown of glucose o Acetyl groups can be used to produce fatty acids
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