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NEUROPHYSIOLOGY Electrical Properties of Nerve cells neurons Electrophysiology of neurons lie in Membrane Physiology Model organisms is Squid Giant Axon SGA diversity of Nervous systems NERVOUS SYSTEM FUNCTIONS 1 gathers sensory input sense organs via Peripheral NS gt 2 integrates information CNS brain amp spinal cordgt 3 responds with motor output effector organs muscle PARTS central nervous system brain and spinal cord nerve bundle of neurons wrapped in connective tissue ganglia cluster of cell bodies of neurons peripheral nervous system carries signals inout of CNS somatic nervous system carries signal to skeletal muscle under conscious control autonomic nervous system signals regulate internally under involuntary control FUNCTIONAL TYPES Sensory neurons affarent neurons carry external stimuli from receptors to CNS lnterneurons integrate amp relay sensory input to motor neuron Motor Neurons efferent neurons convert signals to effector cells response 3202007 El 150 Neurophysiology Structure of avertebrate Neuron Dendrites short outgrowth of Cell Body carry signal into Cell Body Cell Body is main part of cell w cytoplasm amp organelles Axon long outgrowth of cell body carry signal to next nerve Schwann cell cells surrounding axon in vertebrates produce myelin sheath membranelike insulation surrounding axon Nodes of Ranvier space between successive Schwann cells opens nodes speed of conduction wmyelin 100 msec or 200 mihr w myelin speed is less 5 msec Multiple Sclerosis degeneration of myelin sheaths Synaptic Knob enlarged end of neuron holds neurotransmitters in synaptic vesicles Reflex Arc unconscious response to external stimulus neejerk reflex neuromuscular junction is the model for neurophysiology see web EM s u 4x 5 3201007 an 150 Neulophyalology The electrical properties of cells RESTING POTENTIAL the characteristic electric charge exhibited by a cell at rest most often negative potential in electrical terms is amount of electrical charge at one point in an electric circuit compared to some other point in the same circuit measured with a voltmeter multimeter How to measure resting potential in cells inside Vs outside of cells microelectrode SGA 65 to 70 mV i Frog muscle fibers 90 mV i Nitella 150 mV i Valonia 15 mV i r OOCC Vollzge recorder Causes of Resting Potential all make inside H 1 active transport of Na amp K high Na out amp High K in 2 differential permeability Na slower in amp K faster out 3 lots of protein anions inside 4 diffusion of CI in Nernst Emv 62log10 C Ci 3202007 Bil 150 Neulophvsiologv 3 ACI39ION POTENTIAL a selfpropagating change in the voltage across plasma mem rane of a nerve cell name given to changes in electrical charges that occur during the stimulation of a nerve cell usually visualized graphically from an oscilloscope recording PROPERTIES of an AP requires a living cell ie requires 02 for metabolism minated by metabolic poisons as wanide measured using microelectrodes impaled into cells has threshold amount of stimulus needed to fire an AP mena rapid time course 23 msec EVENTS DURING an AP depolarization goes from negative to positive N c annel opens Na floods in 70mV to 50mV repolarization Na channels close amp K channels open K floods out hyperpolarization overshoot of resting potentia I re ractory period time before another AP can fIre39 nme W on m r u anolallullon 9quot pm x gal lam mm E 2 chllrlxallnn a A m 9m x 9m um Kim Membrane potenllal mV 4 iquot J away an a Mormon wwwmn 3202007 EH 15m 7 Neurophysiology 4 CONDUCTION of an AP along an axon local spreading of electric charge change in membrane permeability of adjacent region leads to an autocatalytic quotdomino effectquot mwlumw melon mm 51 Rlnvler r H Synapse functional connection between neurons allows transmission of AP39s between cells synaptic cleft space between neurons across which a chemical transmitter diffuses synaptic knob site of vesicles holding neurotransmitter vesicle holds neurotransmitter ex acetylcholine presynaptic side releases neurotransmitter postsynaptic side a receptor binds transmitter ion channels open change potential charge of postsyna ptic membrane gt new AP removal of stimulus acetylcholine esterase ACHase enz destroys transmitter 3202007 Bil 150 Neurophysiology S PostSynaptic Responses Excitatory neurons gt open Na channels Inhibitory neurons gt open Cl channels no AP EPSP excitatory postsynaptic potential 15mVi excitatory neurons gt open Na channels gt gt AP IPSP inhibitory postsynaptic potential 75mVi inhibitory neurons gt open Cl channels gt more AP all or none 120mv polaorizations 65 to 55mVi Integration of impulses review gures Summation of lmpulses review figures mm 1 synapllr mm Emmy synapw M vanam39c quotmm mum 5mm N c 5g c pulsynaplic gt quotmm 10 7 Axon Axon ol unlock Postsynamic neuron 1 3202007 all 150 r Nemophyslologv Neurotransmitters neuromuscular junction acetylcholine contractions biogenic amines CNS epinephrine amp norepinepherine increase Heart Rate serotonin amp dopamine affect mood attention amp learning psycho active drugs LSDmescaline function by binding to serotonindopamine brain cell receptors Parkinson39s lack of dopamine schizophrenia too much dopamine depression reduced epinephrinenorepinephrine Prozac antidepressant blocks removal of serotonin from synaptic cleft amino acids ASP and GLU excitatory CNS Chinese Restaurant Syndrome GLY amp GABA inhibitory peptides small proteins endorphins decrease perception of pain substance P excitatory transmitter signaling pain Stimulants chemicals that increase activity of CNS cocaine prevents reuptake of Ach by synaptic vesicle caffeine increases postsynaptic threshold CI in stimulates HR amp breathing rate barbiturates amp Valium intensify GABA inhibitory effects Poisons like strychnine prevent loss of transmitter tetanus 3202007 Bil 150 Neurophysiology Dr Mallery Biology 150 Workshop Fall Semester PHOTOSYNTHESIS ANSWERS IN THE GRAND SCHEME Fillin some blanks In Photosynthesis plants convert ilightf energy of the sun into ichemical bondi energy stored in iorganici molecules Plant are iautotrophici organisms that feed themselves in the sense that they make their own organic molecules from iinorganici raw materials Some bacteria are ichemoautotrophsi which means they use energy from oxidizing inorganic substances to produce organic compounds FOR REVIEW Have each member of your Learning Community in turn de ne the KEY TERMS given below and tell how it may relate to the concepts of energy and metabolism As a group help each other answer any questions concerning any portion of the review section that any person does not understand before proceeding further a Thylakoid a attened membrane sac inside the chloroplast used to convert light energy into chemical bond energy Stacks of thylakoid membranes are called grana b Stroma the uid aqueous portion of the chloroplast surrounding the thylakoid membranes contains bacterial size ribosomes DNA enzymes of C02 xation and solutes Also called chloroplasm c Calvin Cycle a major biochemical pathway of photosynthesis involving the reduction of atmospheric carbon dioxide into carbohydrate as glucose d Electromagnetic energy the entire spectrum of radiation produced by the fusion reactions of the sun expressed in wavelengths which run from less than a nanometer to more than a kilometer A portion of the spectrum is referred to as the visible spectrum which includes the light seen by the human eye and runs from 340 nm to 720 nm Absorption spectra a graphical plot of the amount of light absorbed by a purified form of a molecule vs the wavelengths of the electromagnetic visible light PEP Carboxylase an enzyme found in C4 plants which reduces carbon dioxide by combination of C02 with PEP to make malate The efficiency of PEP carboxylase for CO2 is much greater than that of RuBP carboxylase the enzyme of C02 reduction in C3 plants Pigment classes of molecules capable of absorption of light energy chlorophylls carotenoids phycobilins h CAM Plant a plant that uses Crassulacean acid metabolism CAM an adaptation for photosynthesis In arid conditions first discovered in the plant family Crassulaceae C02 entering open stomata during the night is first converted into organic acids malate which releases CO2 for use in the Calvin cycle during the day when the stomata are closed thus these processes are temporally separated Photosystem a light harvesting complex located within the thylakoid membranes amp consisting of an antennae complex of chlorophyll molecules amp a reaction center pigment molecule Cyclic electron flow a route of electron ow during the light reactions of photosynthesis which Involves only photosystem I PSI produces ATP but not NADPH and has the electron returning to its original source pigment P700 k Chemiosmosis the ability of some membranes mitochondrial cristae and chloroplast thylakoid to Use small amounts of captured redox energy to pump hydrogen ions from one compartment to another creating a H gradient and then to harness the energy in this H gradient to make ATP by phosphorylation of ADP through the enzyme ATP synthase C93 00 V v V V Phosphorescence luminescence which is caused by the absorption of radiation at one wavelength followed by a significantly delayed reradiation at a different wavelength and that continues for a noticeable time after the incident radiation stops as opposed to uorescence which is luminescence V Mallery Bil 150 Photosynthesis Workshop ANSWERS Page 1 that is caused by the absorption of radiation at one wavelength followed by nearly immediate re radiation often at a different wavelength and that ceases almost immediately when the incident radiation stops m Photorespiration a metabolic pathway that consumes oxygen like cell respiration and releases carbon dioxide generates no ATP and decreases photosynthetic output of carbohydrate It occurs most commonly on hot dry bright days when plant stomata are closed and the oxygen concentration in the leaf exceeds that of carbon dioxide in Calvin plants 11 Phycobilin a class of accessory pigment composed of a protein and a chromophore group molecule which absorb light two examples include phycoerythrin red algae pigments and phycocyanin bluegreen algae pigments o Plastoquinone a cytochromelike component of the photsynthetic electron transfer chain which undergoes a redox reaction by gaininglosing electrons andor protons CONCEPT MAPS Fill in the following concept map that summarizes this section on Photosynthesis A light energy A lplurcs ongists ul D f lighl radians B in which in which ll cairn C wateris split electrons lo RuB and mm W m D Calv1n cycle 0 NADP to minced 39 m E NADPH by machmum 0f El F enemies hit mantltm ceasi l N G photophosphorylatlon H regenerate RuBP MORE FILLIN THE BLANKS Chloroplasts are found primarily in the mesophyll tissues of a leaf and contain the pigments chorophy carotenes phycobilins The gases 002 and 02 enter and leave the leaf through stomata Veins carry water from the roots to the leaves and distribute sugars made in the leaf to other non photosynthetic tissues LABEL IDENTIFICATIONS A Fill in the blanks in this overview of photosynthesis in a chloroplast light g C02 H20 h Calvin Cycle in the stroma light reaction take place in grana i CHZO sugars 02 ATP NADPH Chlalxulezt reshape9 2 Label the indicated parts in this diagram of the chloroplast 39 a outer membrane granum inner membrane thylakoid compartment thylakoid stroma chloroplasm h apc Mallery Bil 150 Photosynthesis Workshop ANSWERS Page 2 C Label L L 4 neotra and L 39 in the graph below W39hatis the difference between these two spectra On this plot draw an action spectra for rhodopsin a human visual pigment The solid line is the absorption spectra showin absorption maxima at 450nm and 660nm indicating that it isprobably a chlorophyll The dashed line is the action spectra An absorption spectra is a plot vs wavelength of the ammnt of light absorbed which an action spectra is a plot vs physiological activity An action spectrafor rhodopsin would reveal a maxima ofoptical nerve activity near 500nm in the green regions ofthe visible spectrum 450 um 1m 7m 1 111 um um uwpmm Mmquot pmm 1m yhnlmyullqu SOME INTERACTIVE THOUGHT QUESTIONS 1 Why is no oxygen generated by cyclic electron ow A 1 1 1 P51103680 1 1 39 39 39quot739 quotquot3585 there is no need to split water to rereduce the P580 2 Where do the electrons from P700 go during noncyclic electron ow Electron from P700 in PS1 are transferred from the primary electron acceptor to ferredoxin then MDP reductase transfers the electrons to NADP to form MDPH 3 During chemiosmosis in chloroplasts the proton gradient across the membranes is as great as 10 to 20 pH units Name the side of the membrane with the lowest pH Inside the thylakoid compartment the locule space space is the site of the lowest pH greatest H c oncentrations 4 Name 3 things which contribute to the formation of a large pH difference across thylakoid membranes a the transport of protons into the thylakoid compartment by the electron transfer chain b protons splitting from water remaining in the thylakoid compartment and c the removal ofhydrogen in the stroma during the reduction ofM4DP to NADPH 5 What possible explanation is there for photorespiration a process that can result in the loss of as much as 50 of the carbon dioxide reduced in the Calvin Cycle Photorespiration may be an evolutionary relic from the time when there was little oxygen in the atmosphereandtheabquot39y f D 1quot J39 quotL 0 nnrl 39 1 390 ow in mr oxygen rich atmosphere Photorespiration seems to be a great agricultural liability 6 Exactly where does the Calvin Cycle take place in C4 plants In the Bundle Sheath cells 7 Why are C4 plants able to photosynthesize in arid dry conditions while C3 plants would be undergoing Photorespiration Carbon is initially fixed reduced into a ftmrcarbon compound in the mesophyll cells by PEPcarboxylase When this compound is broken down in the bundle sheath cells CO is 1n1 J nnmammm quot 8 In the gure to the right the isolated chloroplasts were rst allowed to equilibrate in r an acidic solution at pH 40 After the chloroplast s thylakoid compartments 1117 reached a pH of 40 the chloroplasts were collected and transferred to a basic solution at pH 80 This caused the chloroplasts to make ATP even ifplaced in the 39 dark Explain The higher concentration ofH ions inside the locules after being 4 equilibrated atpH 40 means that these H ions will movefrom the locules with the existingH ion gradient back mt into the higthmedia low H P concentrations of the stroma probably through theATP synthase in these W A membranes thereby makingATP 1114 gt71 Mallery Bil 150 Photosynthesis Workshop ANSWERS Page 3 ELECTRON FLOW IN THYLAKOID MEMBRANES Label the diagram below A through 1 which depicts the molecules and components of electron ow in photosynthesis hydrogen ions H hydroxyl ions OH ATP ATP synthase locular space NADPH NADP Reductase thylakoid compartment photosystem II F39s105999 A PROBLEM Given the following data 1 the maximum rate ofp nthesis ofgreen plans is about 20 mg gludm39Zhrquot 2 the heat ofcombustion ofglucose is 686 Kcmole the gram molecular weight ofglucose is 180 g How much energy Kcalm could be made over a 18 hr lighted period by a green plant which has a leaf surface area of 2000 dm39z If dm Z make 20 mg ofglucose in I hour then 2 000 dm39Z 20 mgx 2 000 dm z wmld make 40 000 mg or 40 gm ofglucose thus in 18 hours this ammnt leaftissue wmldmake 40gm x 18hr or 720gm ofglucose 720 gm ofglucose is 720gm I80gm 4 moles ofglucose Thus if mole ofglucose releases 686Kcmole then 4 moles 4 x 686Kcmole would release 2 744 Kc of energy enough to run one hard working undergraduate student for a day CHEMIOSMOSIS AGAIN Questions a to f use the gure on the le What is the molecule at label B is gure to the left hydrogen ions What is the name of the system identi ed by label A Electron transfer chain What is label C identifying ATP synthase What is the name ofthe cellular process identi ed by the labels A B amp C Chemiosmosis oxidative phosphorylation What is the name ofthe space labeled D l in chloroplast lacule space 2 in mitochondria Jerimitochondrial space What is the name ofthe space labeled E l i p 2 39 51057 DARK REACTIONS OF PHOTOSYNTHESIS A little easier this time Using the following terms to complete the diagram of the Calvin Cycle given below A term may be used more than once 1 ATP7gt ADPPi a Zand6 39 2 C02 b 6 b 3 glucose and other sugars c 5 i 4 NADPH 7gt NADP d amp e 1 and 4 g D Q j d 5 PGA f 3 p 6 RuBP g 1 summit 39 J Mallery Bil 150 Photosynthesis Workshop ANSWERS Page 4 Major Eukaryotic Organelles NUCLEUS lst described by Robert Brown in 1831 in the stamens of Tradescantia lst isolated by Frederich Meischer in 1871 in wounds Largest organelle maximum dia 10 um volume to 40 um3 10 of cell found in all euc39s except erythrocytessieve tubes evolutionary origin mesosome Components nuclear envelope double membrane bound pore complexes chromatin DNA 5x1012gm histones amp ANP39s heterchromatin condensed amp inactive euchromatin less dense amp active chromosome structure nuCIeosome amp supercoiling nucleolus rDNA genes makes rRNA nucleoplasm soluble phase enzymes RNA39s solutes chromatin etc 3122007 Bil 150 Eukaryotic Di ganelles I Nuclear transport 81 pores Experiments to determine Nuclear Transport amp Pore Sizes 196039s Feldherr injects gold particles in unicell amoeba39s TEM39s show particles near nuclear pores with a minute in 10 min then gold particles in nucleoplasm 197039s used fluorescent tagged proteins showed proteins lt 60000 MW passed 198039s How do large proteins get inout Laskey used nuclear protein nucleoplasmin made in cytoplasm he radioactively tagged it amp autoradiographically followed its movement gt showed nucleoplasmin enters nucleus suggests protein has an aa sequence helps mobility gt aa signal is in tail Conclusion nucleoplasmin holds a special 17 amino acid sequence that targets transport into nucleus called NUCLEAR LOCALIZATION SIGNAL NLS Review chromosome structure 3122007 Bil 150 Eukaryo cic Di ganelles ix MITOCHONDRIA role convert bond energy in foods to ATP couples redox transfer of e amp H to ATP synthase site of cellular respiration redox rx39s CHZO gt C02 gas exchange in cell CO2 released amp O2 reduced Krebs cycle PYRUVATE gt CO2 H20 Res irator ETC chain amp oxidative phos hor lation lst described 190039s Vital req living stains as Janus Green B today fluorescent dyes as dasmine structure elongate cylinders to oblate spheroids 35um by 0510 um dia quotshapeshiftersquot mobile number 20 to 1000 per cell gt in more active cells 20 of cell39s volume double membrane bound organelle outer membrane holds transport protein porin 5K perimitochondrial space where H accumulate inner membrane impermeant req carrier proteins cristae inner membrane holds resp assemblies ETC mitoplasm aqueous compartment of mito holds DNA ribosomes KC etc quot5122007 Bil 150 Eukaryo clc Di ganelles LU PLANT PLASTIDS all are double membrane bound organelles found in all higher plants produce organics required by metazoan cells sucrose PROPLASTID precursor plastid to all the other plant plastids found in apical meristems dividing cells of rootshoot tips cell environment defines type plastids to be made ETIOPLAST develops in dark interior array of cystalline membranes amp yellowchlorophyll precursorlike molecules LEUCOPLASTS nonpIgmentous 2x5 um variable shape 3 types AMYLOPLASTS ALEUROPLAST ELAIOPLASTS CHROMOPLASTS water soluble pigments flower colors CHLOROPLAST develops in light from etioplasts site of autotrophic metabolism ie PHTS 02 evolution CO2 reduction shape variable shape oblate spheroid stelatereticulate size 23 um dia by 510 um long number 152010039scell contents liquid STROMA chloroplasm holds 1 70s ribosomes bacterial size 2 lipid droplets 3 naked DNA pieces supercoiled amp repetitive 4 starch granules amp pyrenoids 5 enzymes of CO2 fixation reduction 6 internal membrane system THYLAKOID Disks GRANA Stacks and INTERG RANAL membranes 3122007 Bil 150 Eukaryo clc Di ganelles ENDOSYMBIONT HYPOTHESIS Proposed by Lynn Margulis 1981 I39Mitochondria amp Chloroplasts are derived from prokaryotes that were once free living and have joined symbiotically with eukaryotic aerobes during cellular evolution Some Evidence Many of today39s single celled eukaryotes live in oxygen poor places gut lack mito amp function anaerobically Pelomyxa palustis euc amoeba that lacks mito amp holds aerobic bacteria in its cytoplasm symbiosis Chloroplasts share a common molecular ancestry with the cyanobacteria lst photosynthetic procaryotes Number striking similarities of Bacteria amp MitoChlp semiautonomous derived from themselves by fission replicate independently from cell have own DNA amp protein biosynthetic systems DNA sequence homology mitochondria to aerobes chlplast to cyanobacteria ribosomes are same size as bacterial 705 double membrane bound a phagocytotic engulfment 3122007 Bil 150 Eukaryo clc Di ganelles RIBOSOME subcell ribonucleoparticle site protein synthesis spheroid 17 to 23 nm dia composed of 2 PARTS small subunit and a large subunit composition 35 protein and 65 rRNA occur free in cytosol or membrane bound on outer surface of ER membranes to mRNA molecule POLYSOME polyribosome ENDOPLASMIC RETICULUM found in all eukaryotic cells with a nucleus structural continuity with nucleus contiuous makes up 50 of all cell39s membranes composed of convoluted 3D membrane network enclosing internal spaces flattened sheets sacs amp tubes of membranes lumen internal compartment up to 10 cell39s volume Rough ER w ribosomes amp Smooth ER without ribosomes Functions RER makes transports amp packages protein vesicles SER lipid amp bile biosynthesis drug detoxification SIGNAL SEQUENCE aa39s Nterm bind release into lumen 33122007 Bil 150 Eukaryo clc Di ganelles GOLGI Part of the ENDOCYTOTIC Pathway cell39s internal membrane system for endocytosis packaging of extracellular molecules for internal digestion amp exocytosis secretory delivery of newly synthesiszed proteinscarbo39s for extracellular secretion size 1 to 3 um dia x 4 to 7 membranes high Number up to 100 per cell two sided three parts CIS side entry sidefaces RER Proteins made on RER lumen gt vesicles gt cis Golgi MEDIAL cisternae elements proteins are modified by adding sulfate carbohydrates amp lipids these modifications help address vesicle to its destination TRANS exit side golgi side modified vesicle leave as export vesicles lysosomes membrane bound vesicles LYSOSOME cytoplasmic single membrane bound vesicle containing hydrolytic enzymes with acid pH optima pH 50 lysosomal membranes have ATP driven membrane Hpump in diverse shapes mostly spherical functions in intracellular digestion autophagy phagosome 3122007 Bil 150 Eukaryo clc Di ganelles 3122007 PROTEASOME a proteIn digesting quotorganellequot large multienzyme complex molecular motor that digest endogenous proteins Such as transcription factors cell cycle cyclins virus coded proteins and improperly folded proteins to short peptides followed by gt hydrolysis of these function Protein Digestion begins when cells add a small polypeptide ubiquitin to a protein to be digested addition of uniquitin targets a protein39s entry into a Proteasome complex Proteasome is a barrelshaped structure made of a lid a base and 4 stacked protein rings with trypsin chymotrypsin and caspace proteolytic activity Bil 1an EukaryoticOrganelles CYTOSKELTON network of protein fibers running throughout the cytoplasm that give a cell its shape amp provide a basis for movement composed of 3 kinds of protein fibers which are universal in eucaryotic cells microfilaments actin 7 to 8nm dia amp indefinite length actin is universal eukaryotic protein from protists to verts 5 of total cell protein filaments of globular protein Gactin conserved a polypeptide of 375aa 1 ATP molecule 3 types of Gactins OLactins of muscle cells B amp V actins of nonmuscle cells internmediate filaments 10nm dia vimentin amp lamin protein fibers ropelike with intermediate diameter span cytoplasm providing framework for mechanical strength made from a heterogenous family of filament proteins microtubules 25nm dia tubulins conserved rigid hollow rods or spiral tubes 2125 nm dia up to several um long make long fibrillar protein complexes form spontaneously repeating globular units 2 different proteins OL amp Btubulin Centriole 9 triplets around 2 forms spindle fibers Basal Body a centriole at base of flagella or cilia Flagella 9 doublets surrounding 2 locomotion amp feeding quot5122007 Bil 150 Eukaryo tlc Di ganelles 9 Intercellular junctions Cell surface regions specialized for intercellular contact esp prominent in epithelial cells impermeabilize areas adhering junctions communication Tight Junctions impermeabilizes prevents leakage of materials between cells fibrillar network at apical ends of cells quotSIXPACK MODELquot Desmosome adhering junctions anchors cells together spot desmosome spot weld with tonofilaments belt desmosome zona adherens Gap Junctions intercellular channels for communication 02nm allows ions electric impulses etc to pass between Plasmodesmata cytoplasmic strands between plant cell walls 70nm makes cells coenocytic quotonecelled compartmentquot Extracellular Matrix protein and polysaccharide complex embedding and protecting cells VACUOLE is a membranebound tonoplast sac that plays roles in intracellular digestion amp the release of cellular waste products Endodermis innermost layer of cells cortex of plant root contains a waterproof Casparian Strip results in SYMPLASTIC ROUTE internal via plasmosdesma APOLPLASTIC ROUTE external via intercellular space 3122007 Bil 150 Eukaryo clc Di ganelles Dr Mallery Biology 150 7 Workshop Fall Semester ENERGY and METABOLISM ANSWERS IN THE GRAND SCHEME The purpose of this workshop is to get the Learning Communities to begin thinking about why certain chemical reactions occur within cells and why there seems to be a directionality to biochemical pathways It is not so important that the students know the names of the molecules in glycolysis Krebs cycle or the electron transfer chain as it is that they understand that energy must be expended to perform all the processes that keeps a cell alive The students need to consider that the real purpose of a biochemical pathways is to conservatively capture small amounts of energy into more useful molecules that can be selected for by a cell later to accomplish some other bit of work Metabolic pathways have evolved as they have because they provide a steady source of replenish able energy cells can use FOR REVIEW A Seven 7 different forms of energy include D Mechanical Heat Sound Electrical 9 light radioactive radiation and D magnetic B a nature of chemical bond pairs of electrons being shared between atoms which represent stored energy potential energy When a covalent bond is broken in a chemical reaction energy is released If the bond being broken is within an organism the organism may be able to use the released energy to do work and carry out its life processes b nucleotides the building blocks of the nucleic acids consisting of a 5carbon sugar a phosphate group and a nitrogenous base adenine thymine cytidine guanine and uracil Nucleotides are also components of the biologically important coenzymes FAD NAD and ATP c Qroton Qqu a proton pump establishes a hydrogen ion gradient across a cell membrane and uses that gradient to produce ATP Protons are actively pumped across the membrane and their diffusion back through special protein channels in the enzyme ATP synthase is coupledto the phosphorylation of ADP with P producing ATP d entrong is defined as a measure of the randomness or disorder of a system Entropy is the tendency of energy to spontaneously convert to a less organized pattern and therefore provides a directionality to all energetic processes ie disorder is constantly increasing in the universe e gotential vs kinetic energy Potential energy is Stored Energy while kinetic energy is the energy of motion f free energy A thermodynamic quantity that is the difference between the enthalpy heat content and the product of the absolute temperature and entropy of a system also called Gibbs free energy Best defined as the energy content in a system available to do work g exergonicendergonic reaction If the products of a reaction contain more free energy after the reaction is complete than the reactants then the reaction is endergonic and another energy source had to contribute in the reaction in order for it to go to completion If the products contain less free energy then the reaction is exergonic and will proceed spontaneously Cells function by coupling exergonic and endergonic reaction together in living systems with the energy released by the exergonic reaction driving the endergonic reaction to completion h QhoSQho anhydride bond Because of the triplet phosphates linked to adenosine the covalent bond linkages are referred to as phosphoric acid anhydrides POP and are considered high energy bonds The term high energy bond is incorrect and misleading as it wrongly suggests that the bond itself contains the energy In fact the breaking of chemical bonds requires an input of energy The free energy released by the hydrolysis of the phosphoanhydride linkages does not come from the breaking of the bond but results from the products of the reaction ADP and P having smaller free energy contents than the reactants The hydrolysis of ATP to ADP P has a AGO difference between reactants and products of 73Kcalmol Maller BIL 150 Energy amp Metabolism Answers Page 1 i aerobic involving oxygen referring to an organism environment or cellular process that requires oxygen j oxidationreduction Oxidation is the loss of an electron by an atom or molecule while reduction is the gaining of an electron by an atom or molecule The e39 is frequently accompanied by a hydrogen proton Oxidation involves the release of energy from the molecule while reduction signi es the addition of energy to a molecule By de nition whenever one substance is oxidized another substance must be reduced39 therefore oxidationreduction reactions redox Rx transfer energy between molecule within cells k chemiosmosis the major pathway by which aerobic cells produce ATP A proton pump in the inner mitochondrial membrane forces protons out of the mitoplasm producing a concentration gradient between the mitoplasm and perimitochondrial space Following their diffusive concentration gradient the protons diffuse back into the mitoplasm through an integral membrane protein ATP synthase which facilitates the phosphorylation of ADP with P anabolic The phase ofmetabolism in 39 39 L t 39 materials of living tissue39 smaller inorganic CO2 and H20 are made into carbohydrates the biosynthetic pathways of cellular metabolism are anabolic Catabolic the metabolic breakdown of complex molecules into simpler ones often resulting in a release of energy39 larger organic are degraded into smaller 39 organics glucose to CO2 and H20 The oxidative pathways of cellular respiration are catabolic m nhowhorvlation To add a 1 A molecule commonly involves adding P to ADP to make ATP39 reactionis o en cat yzed by enzymes called kinases is the primary mechanism by which cells make and transform energy poor compounds into energy rich molecules n dehydrogenase one of the six main classes or types of enzymes that catalyzes the removal and transfer of ydride ion from a donor substrate in an oxidationreduction reaction 0 cytochrome any of a class of ironcontaining proteins that are important in cell respiration as catalysts of oxidationreduction reactions found in the inner cristae membranes of mitochondria V L L ENDERGONIC 5 ENERGY GRAPHS E g H we Products content more Igt Products contut n less 1 energy than reactants energy than reactants ENERGY FLOW The ve terms are A ATP B ADP C P D Energy Added and E Energy released The signi cance of this energy ow diagram is that it indicates that all cellular form energy are derived from the light energy of the sun and are converted into more useful intracellular form ATP ADP P allowing work to be done as the energy is eventually transformed and lost to the cells CELL RESPIRATION STAGE SUBSTANCE S PRODUCED l Glycolys1s ATP amp NADH 2 Fermentation NAD 3 Oxidation of Pyruvate NADH 4 Citric Acid Cycle ATP FADH2 NADH 5 Electron Transfer Chain ATP FAD NADJr Mallery BL 150 Energy amp Metabolism Answers Page 2 ELECTRON TRANSFER CHAIN Paragraph Fill In A NADH E cytochrome proteins 1 proton pumps B FADHz F oxygen J A P C NAD G protons K chemiosmosis D FAD H water GLYCOLYSIS Two phases a an energy investment phase is so de ned because the cell uses ATP to phosphorylate glucose and then fructose raising those glycolytic intermediate to higher free energy states more chemically reactive thereby allowing them to be acted upon and converted into other intermediates providing a favorable directionality for the oxidation of glucose to pyruvate to proceed Glucose is phosphorylated to Glu6P as ATP is hydrolyzed by the enzyme hexokinase and fructose6P is phosphorylated to Fruc l6diP by ATP hydrolysis and b an energyyielding phase occurs when the favorable intermediates produced above now can undergo oxidation producing 2 molecules of NADH where some energy is conserved and can be used to make ATP by Chemiosmosis later in the quot 39 A la 2 39 39 of 39J 39 39 39 J 39 P are oxidized and the electrons used to reduce 2 molecules of NAD Additionally 4 molecules of ADP are phosphorylated to make 4 ATP s by substrate level phosphorylation producing a net yield of 2 ATP thus energy yielding ELECTRON TRANSFER CHAIN Electron Protein Carrier Prosthetic Group coenzyme cytochromes iron heme groups four organic rings binding an iron atom ironsulfur proteins iron and sulfur complexes flavoproteins F MN and FAD F lavin mononucleotide amp F lavin adenine dinucleotide ubiquinone an organic phenolic ring capable of being reduced to a semiquinone or hydroquinone MAXIMUM ENERGY YIELDS in ATP Equivalents for EACH GLUCOSE OXDIZED IN CELL RESPIRATION Reduced ATP Produced by Substrate Level Process ATPS Coenzymes Ox1dat1ve Totals Produced Phosphorylation 4 ATP Glycolysis 2 ATP net 2 NADH 4 to 6 ATP 68 Oxidation of pyruvate none 2 NADH 6 ATP 6 6 NADH 18 ATP Krebs Cycle 2 GTP 2 ATP 2 FADHZ 4 ATP 24 Maller BIL 150 Energy amp Metabolism Answers Page 3 A P IFFERENT KIND OF CONCEPT MAP Process Main Function concept Inputs Outputs oxidation of glucose to 2 pyruvate with net synthesis of 2 glucose 2 pyruvate ATP occurs anaerobically in all cells and as component 2 ATP 4 ATP GIYCOIYSIS part of aerobic respiration 2 NAD 2 net 4 ADP P 2 NADH oxidation of pyruvate to acetyl coA C02 is released as 2 pyruvate 2 acetyl coA part of oxidation of glucose key link of anaerobic to 2 CoASH 2 CO2 Pyruvate to Acetyl39COA aerobic metabolism multienzyme complex involves 5 2NAD ZNADH different coenzymes key regulatory point series of redox reactions that produce NADH amp FADsz 2 acetleoA 2 CoASH GTP an ATP equivalent by substrate level 2 OAA 4 C02 phosphorylation and decarboxylation of glucose C02 2 GTP P 2 ATP Krebs Cycle 6 NAD 6 NADH 2 FAD 2 FADHZ NADH from glycolysis amp Krebs cycle and FADHZ from NADH NAD Krebs transfer electrons to carrier protein molecules FADHZ FAD embedded in the cristae membranes of mitochondria In H HZO series of redox reactions H are pumped into the 12Oz ATP Electron Transfer chain intermembrane space and electrons are passed to 202 ADP P amp oxidative phosphorylation By Chemiosm osis a proton motive force drives H back into mitoplasm through ATP synthase making ATP Regenerates cytoplasmic NAD so that glycolysis may pyruvate NAD Fermentation continue Pyruvate is reduced to ethyl alcohol and C02 NADH ethanol in What may be most important human biochemical Rx COZ Regenerates cytoplasmic NAD so that glycolysis may pyruvate NAD Anaerobic Respiration continue Pyruvate is reduced to lactic acid in anaerobic NADH lactate lactic acid production process and tissues as muscle SOME IDENTIFICATIONS 1 prosawbww O F is the perimitochondrial inner membrane space and is the site of the higher H The space depicted by the label D cytoplasm might also be chosen but is not as correct as the label F The outer mitochondrial membrane is more freely permeable label B Label C is cristae membranes Label D is the cytoplasm ofthe cell The area with the highest H has the lowest pH values and that is label F The site of glycolysis is the cytoplasm of the mitochondria which is label D The molecule that is extruded by the mitochondria is H s The system depicted by the box labeled A is the electron transfer chain Label C is identifying the ATP synthase enzyme responsible for synthesizing ATP The cellular process depicted in this gure by labels A B and C is Chemiosmosis or oxidative phosphorylation Mallery BIL 150 Energy amp Metabolism Answers Page 4 SOME THOUGHT QUESTIONS gt U 0 U P1 7391 What is the net yield of everything produced andor consumed for a every molecules of Glucose that goes through glycolysis 1 glucose is destroyed yielding 2 molecules of pyruvate 4 molecules of ADP are phosphorylated by substrate level phosphorylation making 4 ATP s 2 molecules of NADT are reduced to 2 molecules of NADH Wine is an alcoholic beverage made by FERMENTATION of the juice of the grape The four chemical products made in the process of the fermentation of wines are a NADT b CO2 c ethanol and d lactic acid but also acetic acid vinegar butyric acid of butter and propionic acid a mold inhibitor in breads The alcoholic content of natural wine comes from fermentation Wine contains alcohol because of the yeast that live in the grape juices The yeast carry out fermentation because conditions are anaerobic in a wine vat or bottle where the wine is fermenting Fermentation starts when yeast on the skins of ripe grapes comes into contact with the grape juice called must Run off into casks the new wine then undergoes a series of chemical processes including oxidation precipitation of proteins and fermentation of chemical compounds that create characteristic bouquet After periodic clari cation and aging in casks the wine is ready to be bottled Natural wines do not have alcohol levels higher than about 12 because at higher levels the alcohol becomes toxic to the yeast cells and kills them thus preventing further fermentation or further production of alcohol Oxygen is the terminal nal electron acceptor of the electron transfer chain in oxidative respiration When air containing as little as 01 carbon monoxide by volume is inhaled the oxygen carried by hemoglobin is replaced by the carbon monoxide resulting in fatal oxygen starvation throughout the body When no oxygen is present the preceding electron transfer chain proteins acceptors the cytochromes can not pass along their electrons andor protons The electron transfer chain essentially becomes backlogged or jammed and stops passing electrons Without continued electron transport the chemiosmotic synthesis of ATP stops The ATP synthase which is responsible for making 32 of the total 36 ATP per glucose molecule can not work as efficiently as the proton gradient production slows when the lack of oxygen backs things up As the amounts of ATP drop there is not enough energy to do the work of life eg pumping the heart carrying out vital biochemical reactions and continued muscle contraction Metabolic water is the water formed at the end of the electron transport chain Oxygen is the terminal electron acceptor It combines with the electrons and protons to form a molecule of water This metabolic water formed by the processes of oxidative metabolism within the organism can be sued to help meet the water needs of cells and organisms Fermentation may be inefficient when compared with oxidative respiration but it is still better than nothing at all The ATP yield from glucose may be small in anaerobic conditions but there is still some yield An ugly date is better than no date at all well maybe Fermentation also allows organisms to live in otherwise uninhabitable anaerobic environments and additionally allows normally aerobic cells to keep functioning albeit at a reduced level under temporarily anaerobic conditions eg muscles cells during short sprintstrenuous exercises Jogging is considered aerobic because the cardiovascular system heart and lungs can adjust its activity to continually supply the oxygen needing to keep oxidative respiration glycolysis Krebs cycle and electron transfer functioning harmoniously A continued supply of oxygen is needed to keep these metabolic pathways from backing up see answer C above Sprinting is considered anaerobic because a continued supply of oxygen is not needed nor is continued ATP production by Chemiosmosis What is required is the glycolytic production of ATP albeit small by the anaerobic oxidation of glucose Anything that requires only 2 minute or less of complete exertion is considered to be a sprintanaerobic exercise There is sufficient ATP stores in muscle cells and in the form of creatinephosphate which can convert ADP into ATP in the short term 100 meters Golf is considered nonaerobic I suspect for the maximum exertion is only during the swinging of the golf club so where does baseball t in this remember the words of Roberto Clemente on his induction into the Baseball Hall of Fame Baseball has been berry berry good to me 9 Such short periods of exertion swinging a bat or a golf club lifting a weight throwing a punch etc probably only use up stored muscle ATP andor creatine phosphate and do not call upon glycolysis to produce its 2 ATP net per glucose Maller BIL 150 Energy amp Metabolism Answers Page 5 Dr Mallery Biology 150 Workshop Fall Semester PHOTOSYNTHESIS IN THE GRAND SCHEME Fillin some blanks In Photosynthesis plants convert energy of the sun into energy stored in molecules Plant are 39 reed L uem elve in the sense that they make their own organic molecules from raw materials Some bacteria are which means they use energy from oxidizing inorganic substances to produce organic compounds FOR REVIEW Have each member of your Learning Community in turn de ne the KEY TERMS given below and tell how it may relate to the concepts of energy and metabolism As a group help each other answer any questions concerning any portion of the review section that any person does not understand before proceeding further a Thylakoid i Photosystem b Stroma j Cyclic electron ow c CalvinCycle k Chemiosmosis d Electromagnetic energy 1 Phosphorescence e Absorption spectra In Photorespiration f PEP Carboxylase n Phycobilin g Pigment o Plastoquinone h CAM Plant CONCEPT MAPS Have one member each in turn ll in the following concept map that summarizes this section on Photosynthesis captures consists of D E in which in which stores it in 39 energized d electrons and than 0 pass down reduce 2 r d evolved electmn transport sham NADP 0 retire 394using phosphorylated D U 1 by mechanism of E rearranged to a 4 generates n regenerate release Gsr r in process called using made into j gammaanammhydme MORE FILLIN THE BLANKS Chloroplasts are found primarily in the tissues of a leaf and contain the pigments The gases and enter and leave the leaf through Veins carry water from the roots to the leaves and distribute made in the leaf to other nonphotosynthetic tissues Maller Bil 150 Photosynthesis Workshop Page 1 LABEL IDENTIFICATIONS 1 Fill in the blanks in this overview of photosynthesis in a chloroplast a b c d e f g Chloroplast h l 2 Label the indicated parts in this diagram of the chloroplast a b c d e f C Label the absorption spectra and the action spectra in the graph to the left What is the difference between these two types of gti i la spectra 0 en 5 E 5 E 5 8 9 E ii 5 3 2 399 t a z I I I I l I 400 500 600 700 On this plot draw an actlon spectra for wavelength 0f 1 55 mm rhodopsin a human Visual pigment Absorption and action spectra for photosynthesis Mallery Bil 150 Photosynthesis Workshop Page 2 SOME INTERACTIVE THOUGHT QUESTIONS 1 Why is no oxygen generated by cyclic electron ow 2 Where do the electrons from P700 go during noncyclic electron ow 3 During chemiosmosis in chloroplasts the proton gradient across the membranes is as great as 10 to 20 pH units Name the side of the membrane with the lowest pH 4 Name 3 things which contribute to the formation of a large pH difference across thylakoid membranes 5 What possible explanation is there for photorespiration a process that can result in the loss of as much as 50 ofthe carbon dioxide reduced in the Calvin Cycle 6 Exactly where does the Calvin Cycle take place in C4 plants 7 Why are C4 plants able to photosynthesize in arid dry conditions PM while C3 plants would be undergoing Photorespiration 8 In the gure to the right the isolated chloroplasts were rst allowed xv i to equilibrate in an acidic solution at pH 40 A er the chloroplast s thylakoid compartments reached a pH of 40 the chloroplasts were collected and transferred to a basic solution at pH 80 This caused the chloroplasts to make ATP even if placed in the dark Explain ma ELECTRON FLOW IN THYLAKOID MEMBRANES Label the diagram below a to i with the molecules amp components of electron ow in photosynthesis F39s 9 F strange Maller Bil 150 Photosynthesis Workshop Page 3 A PROBLEM Given the following data 1 the maximum rate of photosynthesis of green plants is about 20 mg gludm39Zhr391 2 the heat ofcombustion ofglucose is 686 Kcmole 3 the gram molecular weight ofglucose is 180 gm How much energy in Kcalmole could theoretically be made over a 18 hr lighted period by a green plant which has a leafsurface area of 2000 dm39Z CHEMIOSMOSIS AGAIN Questions a to f use the gure on the le What is the molecule at label B is gure to the le What is the name of the system identi ed by label A What is label C identifying What is the name of the cellular process identi ed by the labels A B amp C l in photosynthesis 2 in mitochondria What is the name ofthe space labeled D l in the chloroplast 2 in the mitochondria What is the name ofthe space labeled E l in the chloroplast 2 in the mitochondria F1957 D th DARK REACTIONS OF PHOTOSYNTHESIS A little easier this time Using the following terms to complete the diagram of the Calvin Cycle given below A term may be used more than once 1 ATP 7gt ADP Pi a 2 co2 b m 3 glucose and other sugars g g 4 NADPH 7gt NADP c e 5 PGA Gly f eallde J 6 RuBP Maller Bil 150 Photosynthesis Workshop Page 4