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BSC 300, Study Guide Test 2

by: Ashley Bartolomeo

BSC 300, Study Guide Test 2 BSC 300

Marketplace > University of Alabama - Tuscaloosa > Biology > BSC 300 > BSC 300 Study Guide Test 2
Ashley Bartolomeo
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Study Guide!!! Very Detailed!
Cell Biology
John yoder
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This 25 page Study Guide was uploaded by Ashley Bartolomeo on Thursday September 29, 2016. The Study Guide belongs to BSC 300 at University of Alabama - Tuscaloosa taught by John yoder in Fall 2016. Since its upload, it has received 46 views. For similar materials see Cell Biology in Biology at University of Alabama - Tuscaloosa.


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Date Created: 09/29/16
BSC 300 Exam 2 Study Guide Chapter 4 Membrane Structure and Function Plasma Membrane- thin and fragile structure that separates a cell from the external world and is only 5-10nm thick Overview of Membrane Functions 1. Compartmentalization- membranes are continuous, unbroken sheets that enclose compartments a. Plasma membrane encloses the contents of the entire cell b. Nuclear and cytoplasmic membranes enclose diverse intracellular spaces 2. Scaffold for Biochemical Activities- membranes provide the cell with an extensive framework within which components can be ordered for effective interaction 3. Providing a Selectively Permeable Barrier- membranes prevent unrestricted exchange of molecules from one side to the other a. Membranes provide means of communication between the compartments they separate 4. Transporting Solutes- plasma membrane contains machinery possible for transporting substances from one side of the membrane to another a. Also able to transport specific ions, establishing ionic gradients i. This capability is critical for nerve and muscle cells 5. Responding to External Stimuli- plasma membrane uses a process called signal transduction. Membranes possess receptors that combine with specific molecules (ligands) or respond to other types of stimuli such as light or mechanical tension 6. Intracellular Interaction- plasma membrane mediates the interactions between a cell and its neighbors a. Allows cells to recognize and signal one another, to adhere when appropriate, and to exchange materials and information 7. Energy Transduction- membranes are involved in the processes by which one type of energy is converted to another type (energy transduction) a. Most fundamental energy transduction occurs during photosynthesis Brief History of Plasma Membrane Structure  1890s: Ernst Overton concluded that a membrane consisted of lipids and that the more lipid-soluble the solute the more rapidly is would enter the membrane  1925: Gorter and Grendel concluded that the membrane contained a bimolecular layer of lipids, a lipid bilayer o Also suggested that the polar groups of each molecular layer was directed outward toward the aqueous environment  Later research concluded that the plasma membrane was composed of a lipid bilayer that was lined on both its inner and outer surface by a layer of globular proteins  In 1972 a fluid-mosaic model was introduced o The bilayer is present in a fluid state and individual lipid molecules can move laterally within the plane of the membrane o Components are mobile and capable of coming together to engage in various types of transient or semipermanent interactions Chemical Composition of Membranes  Membranes are lipid-protein assemblies help together by noncovalent bonds  Ratio of lipid/protein in a membrane varies, depends on: o Type of cellular membrane (plasma vs. endoplasmic reticulum vs. golgi) o Type of organism (bacterium vs. plant vs. animal) o Type of cell (cartilage vs. muscle vs. liver)  Membrane lipids are amphipathic (hydrophilic and hydrophobic)  There are three main types of membrane lipids: o Phosphoglycerides o Sphingolipids o Cholesterol Phosphoglycerides  Most membrane lipids contain a phosphate group which makes them phospholipids; membrane phospholipids are built on a glycerol backbone which makes them phosphoglycerids  Membrane glycerides are diglycerides – only two of the hydroxyl groups of the glycerol are esterfied to fatty acids; the third is esterfied to a hydrophilic phosphate group  The head group is the polar, water-soluble region of a phospholipid that consists of a phosphate group linked to one of several small, hydrophilic molecules  Fatty acyl chains are hydrophobic, unbranched hydrocarbons o About 16-22 carbons in length o Membrane fatty acid may be  Fully saturated (no double bonds)  Monounsaturated (one double bond)  Polyunsaturated (more than one double bond)  Phosphoglycerides contain one unsaturated and one saturated fatty acyl chain Sphingolipids  Less abundant  Consist of sphingosine linked to a fatty acid by its amino group are called ceramide  Major role in protecting cell surface against environmental factors Cholesterol  Smaller and less amphipathic o Only found in animals o Regulates membrane fluidity Liposomes  Synthetically produced  Used for drug delivery  Carry drugs/inhibitors to specific cells by having cell specific antibody on their outer leaflet  Covered in polyethylene glycol  Fluidity allows membrane to be highly dynamic  Inner and outer leaflets have different lipid composition  Membrane lipids diffuse easily within a leaflet but rarely “flip-flop” from one leaflet to another Membrane Composition Carbohydrates  Glycoproteins: have short, branched carbohydrates  Glycolipids: longer carbohydrate chains  Important in cell recognition and cell-cell interactions Structure and Function of Membrane Proteins 1. Integral membrane proteins – penetrate and pass through the lipid bilayer a. Have hydrophobic transmembrane domains – usually  helices b. Transmembrane Proteins i. Receptors that bind to specific substances and mediate cell response ii. Involved in moving substances across the membrane iii. Transfer electrons during energy transduction iv. Highly regulated v. Can form small aqueous channels through membrane 1. Hydrophilic residues face channel 2. Hydrophobic residues face fatty acyl chains 2. Peripheral proteins – attached to membrane by weak non-covalent bonds a. Easily solubilized b. Located outside of bilayer on extracellular or cytoplasmic side c. Internal proteins function as enzymes and are anchored to catalyze reactions 3. Lipid-anchored membrane proteins: distinguished both by the types of lipid anchor and their orientation a. Glycophosphatidylinositol (GPI)- linked proteins found on outer leaflet b. Prenylation- inner leaflet proteins anchored to lipids by long hydrocarbon chains Membrane Fluidity  Membrane lipids exist in a liquid crystal state  At lower temperatures this movement is restricted  At transition temperature, movement stops and membrane becomes a crystalline gel  Too fluid, membrane will easily disrupt  Not fluid enough, membrane can fracture  Fluidity influenced by o Temperature o Lipid saturation  Cholesterol functions as a fluidity buffer o Low temps cholesterol increases fluidity o High temps cholesterol decreases fluidity  Phospholipids in a leaflet can move laterally  Protein movement limited by interactions with cytoskeleton, other proteins and extracellular materials Movements of Substances Across Cell Membranes  Diffusion: spontaneous process in which a substance moves from high concentration to low concentration  Polarity: more hydrophobic, faster the diffusing rate  Size: large molecules blocked from diffusing  Concentration: molecules cannot diffuse against their concentration gradient by simple diffusion  Charge: combination of concentration and charge constitutes an electrochemical gradient  Solute charge will either increase or decrease its diffusion potential Cell Membranes Are Selectively Permeable  Highly regulated  Movement can occur by passive diffusion or active transport o Passive diffusion: movement down solute gradient; spontaneous  Simple diffusion: solute is small enough to pass through the membrane (O2 and CO2 go through easily)  Facilitated diffusion: due to size or charge exclusion, protein channels that span biological membranes are often deployed; highly specific o Active transport: against solute gradient; requires energy  Osmosis: diffusion of water through a semipermeable membrane o Water diffuses from side of lower electrolyte concentration to side of higher concentration o Cells swell in hypotonic solutions o Cells shrink in hypertonic solutions o Remain unchanged in isotonic solutions  Some cells absorb water at a much higher rate than simple osmosis  Example: kidney cells to produce urine  These cells have specific channel proteins called aquaporin o Protein is very selective Diffusion of Ions Through Membranes  Rapid movement of ions across membranes (conductance) is critical to many cell processes: nerve impulses, muscle contraction  Electrical charge of ions makes them repulsive to the hydrophobic core of the bilayer  Ions must cross through gated ion channels o Highly selective and bidirectional  Voltage gated: Na+, K+, Ca2+, Cl- channel family  Ligand-gated: AchR  Mechano-gated Facilitated Diffusion  Large, polar or ionic substances  Passive, specific and highly regulated  Direction of solute depends on concentration and could be reversible  Glucose transporter is an example of facilitated diffusion o Increased blood glucose levels stimulate secretion of insulin o Insulin responding cells integrate glucose transporter into membrane o Glucose binds to transporter leading to a change in conformation that allows glucose to be released into cell interior Active Transport  Endergonic process that moves molecules against their concentration gradients o Maintain gradients for potassium, sodium, calcium and other ions o Couples movement of substances against gradients to exergonic processes Sodium Potassium Pump  Moves 3 Na+ ions out, 2 K+ ions in  Used for forming action potential in nerve cells  Serves as an energy source to stimulate movement of other molecules  1/3 of all cellular ATP is used to drive this pump  It is a P-type pump: phosphorylation causes change in conformation and ion affinity  Couples ATP hydrolysis to ion transport  In resting state, bound to ATP, pump is open to cell interior and has high affinity for 2 Na+ ions  ATP hydrolyzed, phosphate group transferred to a residue on pump, alters conformation  Pump then has little affinity for Na+ but strong affinity for K+. 2 K+ ions bind  Causes dephosphorylation and again alters pump conformation to original resting state Other Active Transport Systems  H+, Ca2+ and H+/K+  H+/K+ responds to food consumption by pumping H+ ions into the stomach  Prilosec inhibit pump; Zantac block receptors that lead to pump activation ABC Transporters  ABC = ATP-binding-cassette  Large diverse family  Share characteristic core structures o 2 transmembrane domains o 2 cytosolic ATP binding domains  Mutation is responsible for Cystic Fibrosis Cystic Fibrosis Transmembrane Conductance Regulator (CFTR)  ABC transporter  Is a passive cyclic AMP-regulated Chloride channel, not a transporter  Allows Cl- ions to diffuse out of epithelial cells  Suppresses activity of epithelial Na+ channel o Resulting in an osmotic gradient secreting water into the lumen o Water lowers viscosity of mucus and allows infections and bacteria to be cleared Cystic Fibrosis Cause  Absence of CFTR protein o Decreases Cl- o Increases Na+/ H2O reabsorption o Leads to a dehydrated mucus layer o Bacteria cannot be cleared  Results from a single point mutations that prevents the protein from folding correctly Using Light Energy to Actively Transport Ions  Some archaebacterial use a protein called bacteriorhodopsin o Absorbs light energy to transport protons out of cell o Proton gradient is used to make ATP Cotransport  Two substances are simultaneously transported across a membrane by one protein, or protein complex which does not have ATPase activity o Antiports proteins transfer substances in opposite directions o Symport proteins transfer substances in the same direction Nerve Cells Communicate Through Electric Impulses  Cell membrane is negatively charged  Resting potential is -70mV Voltage Gated K+ Channel  Homotetramer  Each subunit has 6 transmembrane helices, including a pore domain and voltage-sensing domain  Could be present in an open/inactivated/close configuration due to protein conformational change Action Potential  Threshold: level of depolarization needed to trigger an action potential (-50mV), which is used to open the voltage-gated Na+ channel  Rising phase: voltage gated Na+ channel open, Na+ ions flow in  Falling phase: voltage gated K+ channel open, K+ ions flow out; Na+ channel inactivated  During refractory period: Na+ channel inactivation; hyperpolarization by increased permeability of K+ ions  All or nothing Synaptic Neurotransmission  Synapse is space between nerve ells  Neurotransmitter can transmit either inhibitory or excitatory signals  AchR is a ligand gated Na+ channel, opening triggers depolarization of postsynaptic membrane (excitatory) Chapter 5 Cellular Respiration: Metabolism and Glycolysis Metabolism: the collection of biochemical reactions that occur within a cell Metabolic Pathways: sequences of chemical reactions  Each reaction catalyzed by a specific enzyme  Pathways convert substrates into end products via metabolic intermediates Thermodynamics Applies to Cell Metabolism  Catabolic pathways: break down complex substrates into simpler end products o Raw material o Chemical energy o Spontaneous, -G o High energy bonds broken, low energy bonds formed o Products have less free energy o Energy not released to surroundings but trapped in other bonds of “energy carries” like ATP  Anabolic Pathways: synthesize complex end products from simpler substrates o Require energy o Use ATP and NADPH from catabolic pathways o Nonspontaneous, +G o Low energy bonds broken, high energy bonds formed o Reactants have less free energy o Energy required to form new bonds comes from catabolism of “energy carries” like ATP Cellular Respiration  Cellular metabolic reaction that convert biochemical energy from nutrients into adenosine triphosphate (ATP), and release waste products  Catabolic  Exothermic oxidation-reduction or redox reaction Oxidation and Reduction  Molecule being oxidized donates electrons to molecule being reduced- aka electron acceptor o May be total transfer – ionization o Or partial transfer – new polar covalent bond formed  When a substrate gains electrons, it is reduced  When a substrate loses electrons, it is oxidized o LEO the GER  Reactant that donates electrons is a reducing agent  Reactant that gains electrons is an oxidizing agent  Oxidation state can be determined by the number of hydrogen vs. oxygen and nitrogen atoms per carbon atom o More hydrogen  more reduced, and more stored energy Oxidation of sugar – cellular respiration:  Glycolysis: first stage. Partially oxidizes glucose. Occurs in cytoplasm  Tricarboxylic (TCA) cycle- completes oxidation of glucose. Occurs in mitochondria (aka Citric Acid Cycle or Kreb’s Cycle)  Very few ATP generated during oxidation  Energy of its bonds is used to reduce “high-energy” electron carriers (NAD+) that deliver electrons to mitochondria  ETC converts energy of electrons to ATP  Complete Oxidation of Glucose o C6H12O6 + 6O2  6CO2 + 6H2O o Net G’ = -686 kcal/mol ATP and ATP Hydrolysis  Phosphate bonds are unstable high energy bonds  Can be easily broken in presence of water  Release of energy results in the formation of more stable products ADP and inorganic phosphate  ATP is rarely hydrolyzed to ADP and Pi  Such hydrolysis releases all free energy as heat  ATP hydrolysis is a multistep process  It takes places as the phosphate group is removed from ATP and transferred to a new substrate molecule  ATP hydrolysis is complete when a free inorganic phosphate is released into solution  Inorganic phosphate is very stable – low energy – molecule Glycolysis  Occurs in cytoplasm  Glucose  pyruvate  C6H12O6 + 2ADP + 2Pi + 2NAD+  2 pyruvate + 2ATP + 2NADH + 2H+ + 2H2O  There are three reactions called the irreversible reactions that drive the entire process forward o They are 1, 3 and 10 Energy Investment Phase Hydrolysis of ATP in 2 or the first 3 reactions 1. Glucose is phosphorylated to glucose 6-phosphate by hydrolysis of ATP; done by hexokinase 2. Glucose 6-phosphate is isomerized to fructose 6-phosphate 3. Fructose 6-phosphate is phosphorylated to fructose 1,6-bisphosphate using ATP; done by phosphofructokinase 4. F1,6bP splits into 3 carbon molecules, glyceraldehyde 3-phosphate and dihydroxyacetone phosphate 5. An isomerase interconverts the two molecules and G3P is siphoned off by step 6 6. Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) dehydrogenates and adds an inorganic phosphate to glyceraldehyde 3-phosphate producing 1,3-bisphosphoglycerate  Glyceraldehyde-3-phosphate is oxidized by the coenzyme nicotinamide adenine dinucleotide (NAD)  The molecule is phosphorylated by the addition of a free phosphate group; the enzyme is glyceraldehyde-3-phosphate dehydrogenase (GAPDH) 7. Phosphoglycerate kinase transfers a phosphate group from 1,3- bisphosphoglycerate to ADP to form ATP and 3-phosphoglycerate 8. The enzyme phosphoglycero mutase relocates the P from 3- phosphoglycerate from the 3 carbon to the 2 ndcarbon to form 2- phosphoglycerate 9. The enzyme enolase removes a molecule of water from 2- phosphoglycerate to form phosphoenolpyruvic acid (PEP) 10. The enzyme pyruvate kinase transfers a P from phosphoenolpyruvate (PEP) to ADP to form pyruvic acid and ATP Steps 1 and 3 = -2 ATP Steps 7 and 10 = +4 ATP Net “visible” ATP produced = 2 Metabolism Fermentation Process  Fermentation restores NAD+ from NADH  Anaerobic conditions- glycolysis depletes supply of NAD+ by reducing it to NADH  If NAD+ is absent, glycolysis cannot continue  In yeast, pyruvate is reduced and converted to ethanol  In muscle and tumor cells pyruvate is reduced to lactate Cancer Metabolism  Cancer cells exhibit up to 200x the glycolytic rate of normal cells  Produce bulk of ATP via glycolytic substrate level phosphorylation and NAD+ recycling  Likely related to: o Many proliferating cells preferentially perform aerobic glycolysis:  ATP production is inefficient, but rapid  Glucose metabolites are a readily available sources for synthesis of other building blocks  Most cancers express fetal form of pyruvate kinase (PKM2)  Pyruvate kinase catalyzes the third irreversible step of glycolysis (step 10)  PKM2 has higher Km than adult PK o Limits production of pyruvate o Enhances cell division o Promotes dedifferentiation o Enhances glucose uptake Reducing Power  ATP = energy source for anabolic processes  NADPH donates electrons to build large biomolecules o NADPH is a non-protein coenzyme o Supply of NADPH represents cell’s reducing power o NADP+ is formed by phosphate transfer from ATP to NAD+ o Then it is reduced to NADPH  NADPH and NADH have different metabolic roles  Coenzymes for different enzymes  Anabolic pathways use NADPH  Catabolic processes use NAD+ o NADPH favored when energy is abundant o NADH use to make ATP when energy is scarce Pentose Phosphate Pathway  Parallel anabolic pathway to glycolysis  Produces NADPH by oxidation of glucose-6-phosphate  Yields the 5 carbon ribose-5-phosphate used to make nucleic acids  And a 4 carbon sugar necessary for some amino acids Metabolic Regulation  Enzymes are controlled by alteration in active sites o Covalent modification of enzymes regulated by protein kinases o Allosteric modulation of enzymes regulated by compounds binding to allosteric site  Feedback inhibition, the product of the pathway allosterically inhibits one of the first enzymes of pathway Separating Catabolic and Anabolic Pathways  Metabolites of many catabolic pathways can be used to regenerate stores of the starting material o Example, when blood sugar levels drop, pancreas stops making insulin and releases glucagon; stimulating liver cells to convert glycogen to glucose and generate glucose from various metabolites including pyruvate – gluconeogenesis  Glucagon signaling regulates many enzymes both positively and negatively  Glucagon leads to phosphorylation and inactivation of phosphofructokinase  Activating phosphorylation of fructose bisphosphatase stimulates gluconeogenesis  Glucagon inhibits production of the phosphofructokinase activator fructose 2,6 bisphosphate An Overview of Glycolysis 1. What are the irreversible steps? Why are they irreversible? 2. What is the committed step? Why does it have this name? 3. Know the substrate, enzyme and product of these 3 steps 4. How is NAD+ reduction linked to ATP synthesis? 5. What is the net production of glycolysis? I.e. What goes in, what comes out? 6. What happens in the presence of oxygen? In the absence of oxygen? 7. What is the role of isomerases? 8. What is the role of dehydrogenases? Chapter 5 Aerobic Respiration and the Mitochondrion Introduction  Early earth populated by anaerobes  Oxygen accumulated after cyanobacteria appeared because of photosynthesis  Aerobes then evolved to use oxygen to extract more energy  In eukaryotes, aerobic respiration happens in mitochondria Structure of a Mitochondrion  Outer mitochondrial membrane: similar in lipid composition to eukaryotic plasma membrane  Has integral proteins called porins o Allow metabolites, ions and small proteins to freely diffuse into intermembrane space  Inner mitochondrial membrane: lipid composition similar to prokaryotic membrane  Divided into two domains o Inner boundary membrane: regulates traffic in and out of matrix o Cristae: proteins of electron transport chain located  Also increases surface area of mitochondria  Mitochondrial matrix o Space enclosed by inner membrane. Highly concentrated o Major functions include oxidation of fatty acids, and the citric acid cycle o Has several copies of circular DNA o RNA and proteins can be synthesized in matrix Mitochondria Function  Apoptosis  Cell signaling  Differentiation  Control of cell cycle and cell growth  Synthesis of amino acids  Uptake and release of Ca2+  Has a diverse shape  Size/number reflect varied requirements of cell  Responds to cellular needs by growth and fission  Fusion protects cell from damaged mitochondrial DNA Oxidative Metabolism in the Mitochondrion  First steps carried out by glycolysis o Produces 2 pyruvate, 2 NADH and 2 ATP o Aerobic organisms use O2 to extract more than 30 additional ATPs from pyruvate and NADH Pyruvate Dehydrogenase Complex Links Glycolysis to TCA Cycle  Pyruvate dehydrogenase: a huge protein complex that catalyzes this critical 3-step reaction o Several vitamin derived co-enzymes including NAD+ and Coenzyme A  Pyruvate dehydrogenase actively transports pyruvate across inner membrane  In three catalytic steps the enzyme: o Decarboxylates pyruvate releasing CO2 o The acetyl group is transferred to Coenzyme A forming acetyl CoA o Reduces NAD+ to NADH  Acetyl CoA links glycolysis to TCA cycle through the action of the pyruvate dehydrogenase complex The Tricarboxylic Acid (TCA) Cycle A stepwise cycle in which acetyl CoA is completely oxidized and its energy captured in reduced carriers (NADH and FADH2) 1) Acetyl CoA joins with a four carbon molecules, oxaloacetate, releasing CoA group and forming a six carbon molecule called citrate 2) Citrate is converted into its isomer, isocitrate 3) Isocitrate is oxidized and releases a molecule of CO2 leaving behind a five carbon molecule - -ketoglutarate. NAD+ is reduced to form NADH. Enzyme catalyzing this step, isocitrate dehydrogenase is important in regulating the speed of the citric acid cycle 4) - ketoglutarate is oxidized, CO2 is removed and Coenzyme A is added to form the 4 carbon compound succinyl-CoA. The enzyme that catalyzes this reaction is alpha-ketoglutarate dehydrogenase 5) CoA is removed from succinyl-CoA to produce succinate. Energy released is used to make GTP from GDP and Pi by substrate level phosphorylation. The enzyme succinyl-CoA synthase catalyzes this reaction 6) Succinate is oxidized to fumarate. FAD is reduced to FADH2. Enzyme succinate dehydrogenase catalyzes the removal of two hydrogens from succinate 7) Fumarate is hydrolyzed to malate and is catalyzed by fumarase (fumarate hydratase) 8) Malate is oxidized to produce oxaloacetate, the starting compound of the citric acid cycle by malate dehydrogenase. NAD+ is reduced to NADH + H+  At the end of the Citric Acid Cycle per two molecules of pyruvic acid there is two ATP molecules, ten NADH molecules and two FADH2 molecules produced To remember the molecules of the citric acid cycle Can- citrate Adam- cis-aconitate (intermediate step don’t need to know) Intrigue- isocitrate A- alpha-ketoglutarate Super- succinyl CoA Sexy- succinate Foxy- fumarate Mama- malate Ok! – oxaloacetate To remember the enzymes of the citric acid cycle So- synthase At- aconitase Another- aconitase Dance- dehydrogenase Devon- dehydrogenase Sipped- synthetase Down- dehydrogenase Five- fumarase Drinks- dehydrogenase Key to remembering how many CO2 or NADH is made you need to remember that 3 out of 4 dehydrogenase enzymes will remove 2 H atoms (and an electron) from the molecule and put it onto a NAD, and remove a CO2 molecule. The NAD become NADH and the only exception to this rule is the enzyme fumarate; it places 2 H atoms on an FAD molecule instead of NAD What you need to know  Importance of CoA and the resulting thioester bond in driving the cycle forward and producing an ATP/ GTP molecule  The functional definition of dehydrogenase enzymes and their importance in reducing NAD+ and FAD  Citrate synthase as the key regulated enzyme in this cycle  Succinate dehydrogenase as a shared enzyme between TCA cycle and ETC There are four oxidation reduction reactions in the TCA cycle  Three reactions: NAD+ reduced to NADH + H+  One reaction: FAD reduced to FADH2  Two C released as CO2 The Fatty Acid Cycle: -oxidation  Reaction intermediates of TCA cycle are also common metabolites generated in other catabolic reactions, making the TCA cycle the central metabolic pathway of the cell  Fats are oxidized in the mitochondria by -oxidation to generate Acetyl CoA  Two dehydrogenase enzymes consecutively oxidize carbons 2 and 3 of the fatty acyl chain. This reduces one FAD and one NAD+.  Another enzyme cleaves acetyl CoA and joins another CoA to the shortened chain  Released acetyl CoA fed into TCA cycle  Each turn of fatty acid cycle generates: o 4 NADH o 2 FADH2 o 1 ATP equivalent Fats  Provide a significant source of energy  Stored as triglycerides in fat droplets in adipose cells. Upon glucagon stimulation, are cleaved form glycerol and released to bloodstream  Transported into body cells and in ATP are covalently attached to CoA at their carboxyl end  Fatty acyl CoA transported into mitochondrion for energy extraction via the -oxidation pathway Peroxisomes  Membrane bound vesicles  Breakdown diverse biomolecules  Use O2 to oxidize these substrates producing H2O2  Peroxisomal enzyme catalyse converts H2O2 to O2 and H2O  Two critical functions include: o -oxidation of very long chain fatty acids (VLCFAs): FA tails longer than 22 carbons. The shorter FA-CoA molecules then transported to mitochondria o production of plasmalogen, a lipid enriched in cardiovascular and myelin cell The Glycerol Phosphate Shuttle  FADH2 and NADH are primary products of the TCA cycle  Inner mitochondrial membrane is impermeable to NADH  Electrons of glycolytically produced NADH must be actively transported into the mitochondrial matrix If they are to be used in the electron transport system  There are two processes, the Malate-aspartate and the Glycerol phosphate shuttle systems oxidize cytoplasmic NADH and shuttle its electrons into the matrix  Cytoplasmic NADH is used to enzymatically reduce oxaloacetate to malate or DHAP to G3P  In glycerol phosphate system an inner transmembrane dehydrogenase enzyme uses the electrons to reduce FAD to FADH2  Malate-aspartate shuttle first transports malate into the matrix where a dehydrogenase reduced NAD+ to NADH Summary of Oxidative Phosphorylation Importance of reduced coenzymes  Electrons from NADH and FADH2 are passed through electron transport chain  They provide energy to pump H+ across inner membrane to inter membrane space  ATP formed by controlled flow of H+ back into matrix through ATP- synthesizing enzyme ATP synthase  Coupling of H+ translocation to ATP synthesis is called chemiosmosis  Three ATP formed from each pair of electrons donated by NADH’ 2 ATP formed from each pair of electrons donated by FADH2 Second Half of Chapter 5 Aerobic Respiration and the Mitochondrion Oxidative Phosphorylation 1. Electron Transport Chain establishes a H+ electrochemical gradient 2. Flow of protons drive ATP production via ATP synthase  About 3 ATPs per NADH generate during TCA  About 2 ATPs per FADH2 Redox Potential: a measure of the tendency of a chemical species to acquire electrons and thereby be reduced. More positive the redo potential, stronger the affinity for electrons  O2 is a strong oxidizing agent: high affinity for electrons  NADH is a strong reducing agent: weak affinity for electrons  Electrons passed along ETC from one acceptor to another, electrons being passed to a molecule with more positive redox potential Electron Transport Chain  Electrons associated with NADH or FADH2 used to reduced electron carriers associated with four inner membrane protein complexes  Energy releasing reactions coupled to conformational changes in complexes  These changes move protons (H+) across inner membrane into intermembrane space, establishing an electrochemical gradient called proton motive force  All but ubiquinone are prosthetic groups, non-protein molecules, strongly bound to protein complexes Electron Carries 1. Flavoprotein  Polypeptides containing 1 of 2 related prosthetic groups o FMN (Flavin mononucleotide) o FAD (Flavin adenine dinucleotide) o Each accepts and donates 2 protons and 2 electrons  FMN found in complex 1  FAD found in complex 2 2. Cytochromes  Possess heme prosthetic groups with iron centers o Alternate between Fe+2 and Fe+3 by gain or loss of single electron o 3 cytochromes in complexes 3 and 4 3. Three Copper Atoms  Complex 4  Accept and donate a single electron  Alternate between Cu2+ and Cu1+ 4. Iron-sulfur Proteins  Iron linked to non-heme sulfur centers in 1,2,3  Accept and donate a single electron 5. Ubiquinone (coenzyme Q)  No prosthetic group o Lipid soluble  Accepts and donates 2 electrons and protons o Partially reduced = ubisemiquinone o Fully reduced = ubiquinol Electron Transport Chain Complex 1: NADH dehydrogenase complex  Catalyze transfer of electron pair from NADH to uniquinone  Electrons transferred from NADH to FMN then through 7 Fe-S centers  Electrons reduce uniquinone to ubiquinol  Release 4 H+ into intermembrane space  Uniquinol now delivers to Complex 3: The Cytochrome b,c complex Complex 2: Succinate dehydrogenase complex  Catalyzes reduction of FAD to FADH2  No proton transfer  Electrons reduced ubiquinone to ubiquinol which then delivers them to complex 3 Complex 3: Cytochrome bc  Accepts 2 electrons from ubiquinol  Reduce 2 cytochrome 2 (1 electron at a time) in a complex called Q cycle  4 H+ pumped into intermembrane space Complex 4: Cytochrome Oxidase  Transports 2 H+ to intermembrane space  4 Cytochrome c are required  Four electrons and 4 H+ from matrix reduce O2 making two H2O  O2 is the terminal electron acceptor Machinery for ATP Formation  ATP synthase: multi subunit complex. Contains a rotor and a stator  F0 Particle: embedded in inner membrane, provides channel for H+ to flow down electrochemical gradient back into matrix  Projecting from F0 particle is a protein rotator, the -subunit o -subunit has asymmetric shape  Essential for function of ATP synthase  F1 particle: tethered to membrane by a stator protein. Head contains catalytic subunits that phosphorylate ADP  As H+ diffuse down gradient ATP synthase F0 channels, cause this portion to rotate  -subunit induces conformational changes within catalytic subunits of the F1 particle that drives the catalysis of ADP phosphorylation  F1 composed of 3 pairs of alpha, beta subunits – beta subunit possesses catalytic site for ADP phosphorylation  Binding sites on beta subunit o Open to release ATP and then bind ADP and Pi o Loose to hold ADP and Pi in position o Tight for induced fit and chemical reaction  3 H- required to drive these conformational changes  9 H+ per complete rotation of  subunit to generate 3 ATP  Each NADH transfer 10 H+ into intermembrane space  Each FADH2 approximately 6 H+ Balance Sheet for ATP Production 8 NADH from 2 pyruvate via 24 Pyruvate Dehydrogenase and TCA cycle @ ~3 ATP/NADH 2 FADH2 from 2 pyruvate through 4 TCA cycle @ ~2 ATP/FADH2 Total from oxidative phosphorylation GTP/ATP from 2x TCA cycle 2 2 NADH from glycolysis @ ~2-3 4-6 ATP/NADH Net ATP generated during glycolysis2 TOTAL from glycolysis and TCA 36-38 cycle


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"Knowing I can count on the Elite Notetaker in my class allows me to focus on what the professor is saying instead of just scribbling notes the whole time and falling behind."

Allison Fischer University of Alabama

"I signed up to be an Elite Notetaker with 2 of my sorority sisters this semester. We just posted our notes weekly and were each making over $600 per month. I LOVE StudySoup!"

Bentley McCaw University of Florida

"I was shooting for a perfect 4.0 GPA this semester. Having StudySoup as a study aid was critical to helping me achieve my goal...and I nailed it!"

Parker Thompson 500 Startups

"It's a great way for students to improve their educational experience and it seemed like a product that everybody wants, so all the people participating are winning."

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Refund Policy


All subscriptions to StudySoup are paid in full at the time of subscribing. To change your credit card information or to cancel your subscription, go to "Edit Settings". All credit card information will be available there. If you should decide to cancel your subscription, it will continue to be valid until the next payment period, as all payments for the current period were made in advance. For special circumstances, please email


StudySoup has more than 1 million course-specific study resources to help students study smarter. If you’re having trouble finding what you’re looking for, our customer support team can help you find what you need! Feel free to contact them here:

Recurring Subscriptions: If you have canceled your recurring subscription on the day of renewal and have not downloaded any documents, you may request a refund by submitting an email to

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Please Note: Refunds can never be provided more than 30 days after the initial purchase date regardless of your activity on the site.