Exam 3 Review CHAPTER 8 10 16 2013 1 Metabolism All of the chemical reactions occurring in a cell Uptake of matter and energy Conversion to usable form Synthesis of cellular materials Elimination of waste products Metabolic Pathways o Catabolic Pathways Releases energy by breaking down complex molecules to simpler molecules o Anabolic Pathways Consume energy to build complex molecules from smaller ones 2 Energy The capacity to do work o Kinetic Energy Energy of motion o Potential Energy Positional 3 Laws of thermodynamics 1st law of thermodynamics Energy can be transferred or transformed but it cannot be destroyed During every transfer or transformation some energy becomes unavailable to do work Entropy disorder 2nd law of thermodynamics Every energy transfer or transformation increases the entropy of the universe The entropy of a particular system such as an organism may actually decrease so long as the entropy of the universe increases 4 Energy within a system Free Energy G portion of energy available to do work G H TS Free energy Total Energy Temperature Entropy Organisms tend to move toward stability not entropy 5 Endergonic Exergonic Reactions Exergonic Energy outward Net release of energy Endergonic Energy inward Absorbs free energy from its Breaking of bonds does not release energy surroundings 6 Enzyme An enzyme is a catalyst it is a chemical agent that speeds up a reaction by lowering energy barriers The reactant an enzyme acts on is known as the substrate The active site binds to the substrate It is a pocket or groove on the enzyme where the catalysis occurs The specificity of an enzyme is based on the shape of the substrate and the shape of the active site Competitive inhibitor Reduce the productivity of enzymes by blocking substrates from entering the active sites increase substrate so that more substrate than inhibitor can enter active sites Inhibitors Non competitive inhibitor impede by binding to another part of the enzyme changing the shape of the enzyme making it hard for the active site to react with the substrate CHAPTER 9 1 Redox Reactions Oxidation loss of electrons loss of energy Reduction gain of electrons gain of energy NAD is well suited as an electron carrier because it can transform easily between oxidized NAD and reduced NADH states 2 Cellular Respiration Overview Glycolysis Cytosol breaks down glucose into two molecules of pyruvate C3 CoA Bridge Reactions Mitochondrion Pyruvate is oxidized into Acetyl Krebs Cycle Citric Acid Cycle Breakdown of glucose to carbon dioxide is completed Electron Transport Chain Accepts electrons from the breakdown of the first steps of cellular respiration and passes them to other molecules Electrons combine with hydrogen and oxygen forming water Oxidative Phosphorylation Synthesizing ATP from ADP Substrate level phosphorylation Enzyme transfers a phosphate group from a substrate molecule to ADP rather than adding an inorganic phosphate to ADP as in oxidative phosphorylation 3 Glycolysis Sugar splitting Occurs whether or not oxygen is present Glucose is split into two pyruvate molecules C3 2 ATP investment 4 ATP payoff 2 ATP net gain NAD is reduced to NADH 2 NADH yield 4 The Bridge Reaction Location Mitochondrial Matrix Upon entering the mitochondrion the 2 pyruvates are converted into Acetyl CoA 5 The Krebs Cycle Citric Acid Cycle Location Mitochondrial Matrix Releases C02 Extracts energy primarily as the reduced high energy electron carriers NADH and FADH2 NADH and FADH2 transfer chemical energy from metabolic intermediates to the electron transport chain to create a different form of energy a gradient of protons across the inner mitochondrial membrane The activity of the Krebs cycle is closely linked to the availability of oxygen although none of the steps in the pathway directly use oxygen Acetyl CoA joins with oxaloacetate forming citrate Step 1 The following 7 steps are citrate regenerating oxaloacetate which is what gives the name cycle meaning 2 ATP produced during citric acid cycle 6 Oxidative Phosphorylation AEROBIC Uses energy released by the electron transport chain to power ATP synthesis 7 Electron Transport Chain Location Inner mitochondrial membrane Electron Transport Chain is a collection of molecules embedded in the inner membrane of the mitochondria in eukaryotes Oxidizes NADH and FADH2 Generates a proton gradient that is used to produce ATP o Indirectly produces ATP 8 Chemiosmosis Location Inner mitochondrial membrane For every NADH that feeds into the electron transport chain 2 protons pumped into inner membrane space For every FADH2 2 protons For every proton that goes through ATP synthase 1 ATP produced 9 Fermentation Produces ATP and regenerates NAD under anaerobic conditions Glycolysis still takes place Pyruvate is reduced instead of being oxidized Alcohol Fermentation o 2 Pyruvate acetaldehyde 2 CO2 Lactic Acid Fermentation o Pyruvate Lactate NADH NAD 38 ATP 2 from glycolysis 2 from Krebs 34 from electron transport Autotrophs sustain themselves without eating anything derived from other living beings Producers Heterotrophs obtain nutrition by the second major mode of nutrition consumers CO2 and H2O enter the leaf through pores called stomata Water is absorbed by the roots and transported to the leaves through the vascular bundles Pre Test Metabolism is best described as Induced fit makes the active site fit ore snug around the enzyme Energy is released by hydrolysis of ATP What is not included in the work of muscle cells Oxidation loss of electrons from a substance LEO Loss equals oxidation loss of energy Reduction addition of electrons to a substance GER Gain equal reduction gain of energy The reaction that connects glycolysis to the Krebs cycle the bridge reaction is the oxidation of pyruvate to acetyl CoA Krebs mitochondrial matrix The electron transport chain is located in the inner mitochondrial membrane The electron transport chain is made of a series of electron carrier molecules embedded in the inner mitochondrial membrane 10 16 2013 10 16 2013
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