Presentation on theme: "Chapter 7: Cellular Respiration"— Presentation transcript:
1 Chapter 7: Cellular Respiration How Cells Make ATP:Energy-Releasing Pathways
2 FYICoupled reactions (otherwise known as oxidation-reduction reactions - REDOX ), fermentation, cell respiration and photosynthesis are some of the most challenging concepts in biology.Note that questions on the AP Biology Exam are most likely to focus on the net results of photosynthesis and respiration and not on the exact reactions that create the products.
3 Summary:Cellular respiration - the process by which your cells transfer the energy in organic compounds to ATP.The byproduct of this reaction is water and carbon dioxide.It occurs in the cells mitochondria, which are the energy producers for the cell.
4 Summary:Each cell converts the energy in the chemical bonds of nutrients to chemical energy stored in ATPMay be aerobic or anaerobicMost cells use aerobic respiration3 pathways that are exergonic and release energy:Aerobic respirationAnaerobic respirationFermentation
5 Aerobic Respiration Most eukaryotes and prokaryotes Requires oxygen To obtain energy from glucoseRequires oxygenNutrients are catabolized to CO2 and H2OGlucose + Oxygen Carbon Dioxide + Water Energy (in bonds of ATP)
6 Aerobic Respiration A redox process Glucose is oxidized to form Carbon DioxideOxygen is reduced, forming waterThe electrons produced are used to form ATP
7 Aerobic Respiration 3 stages: Glycolysis Citric Acid (Krebs) Cycle Electron Transport Chain and Chemiosmosis
8 Aerobic Respiration*In eukaryotes, glycolysis occurs in cytosol and remaining 2 steps occur in mitochondria.* In bacteria, all stages occur in cytosol working with plasma membrane.
9 Glycolysis Occurs in cytosol Glucose converted to two 3-carbon molecules of pyruvic acidATP and NADH are formedNADH - temporarily stores large amounts of free energyEnergy from NADH ultimately participates in reactions that form ATPNet production of 2 ATPAnimation of Glycolysis
10 Advantages of Glycolysis The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen.
12 Citric Acid Cycle (Krebs Cycle) Pyruvic Acid from Glycolysis moves into mitochondria.Pyruvic acid breaks apart1 molecule of CO2 is produced2 other Carbon atoms form acetyl CoAAcetyl CoA combines with 4 carbon molecules to produce citric acid.
13 Citric Acid Cycle (Krebs Cycle) Citric Acid is broken downCO2 releasedElectrons transferred to energy carriers.Carbon Dioxide is a waste productATP, NADH and FADH2 are produced2 ATP are produced/glucose
15 Electron Transport Chain and Chemiosmosis Electrons from Krebs cycle are passed to NADH and FADH2 in Electron Transport ChainEnzymes present in mitochondrial membraneAs NADH and FADH2 pass along enzymes, they give up electrons (energy) = chemiosmosisH+ ions are transported across membrane and come in contact with ATP synthaseADP + Pi = ATP
19 Aerobic Respiration – End Results One glucose gives maximum of ATP’sGlycolysis produces 2 ATP molecules2 ATP molecules are produced in the citric acid cycleRemainder of ATP is produced in the electron transport system (32 or 34)Efficiency is about 40%; remaining energy is disseminated as heat
20 Other nutrients (besides glucose) provide energy More energy is gained from burning fats than glucoseLipids contain 9 kcal/gramLipids are broken down and glycerol enters glycolysisFatty acids are converted to acetyl CoA and enter the citric acid cycleProteins are broken down to amino acidsProteins contain 4 kcal/gram
21 Anaerobic Respiration and Fermentation do not Require Oxygen Various inorganic substances serve as the final electron acceptorYield is only the 2 ATP molecules from glycolysisTypes of FermentationAlcoholLactate
22 Alcoholic Fermentation Alcoholoic fermentationAlcoholic fermentation produces ethanolPyruvate is converted to ethanolEthanol is a potentially toxic waste productYeast carry out alcoholic fermentation when oxygen deprivedPyruvic acid + NADH -> alcohol + CO2 + NAD+
23 Lactate FermentationBacteria and some fungi carry out lactate fermentationStrenuous exercise in mammals results in lactate fermentation as wellYields only the 2 ATP molecules from glycolysisPyruvic acid + NADH -> lactic acid + NAD+
24 Copyright Pearson Prentice Hall FermentationLactic acid fermentation converts glucose into lactic acid. The first part of the equation is glycolysis. The second part shows the conversion of pyruvic acid to lactic acid.Copyright Pearson Prentice Hall
25 Group Assignment: Glycolysis Krebs Cycle Electron Transport Chain/ChemiosmosisAlcoholic FermentationLactate Fermentation