Exam 2 Study Guide
Exam 2 Study Guide BIOL 3510
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This 11 page Study Guide was uploaded by Marin Young on Sunday March 6, 2016. The Study Guide belongs to BIOL 3510 at University of North Texas taught by Dr. Chapman in Spring 2016. Since its upload, it has received 228 views. For similar materials see Cell Biology in Biological Sciences at University of North Texas.
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Date Created: 03/06/16
Exam 2 Study Guide BIOL 3510 Notes by Marin Young Thursday lVlarch Ply Questions from the review bank III What are cell membranes composed of and what roles do membranes play in a cell 0 Mostly phospholipids with proteins and other lipids present 0 Five majorfunctions are receiving information moving molecules in and out moving the cell forming subcellular compartments and energy transduction especially by making gradients meaning one side has more of something than the other III Describe the general structure of a phospholipid Compare to glycolipid How do phospholipids glycolipids and sterols orient into membranes 0 A phospholipid has a polar head region and two fatty acid quottailsquot I The head includes a glycerol backbone where tails attach a phosphate group and an amino acid or some other polar molecular tag like choline I The tails are hydrocarbons with mostly carboncarbon single bonds III Some have one or more carboncarbon double bonds which have cis configuration and cause a bendkink in the fatty acid chain 0 A glycolipid also has two fatty acid tails attached to a backbone but the backbone can be different like ceramide and the molecular tag is a sugar mono di or oligosaccharide I Ceramide is noteworthy because it can form hydrogen bonds I Glycolipids are important to cell recognition and signaling 0 Membranes are made mostly of a phospholipid bilayer with heads facing the environments and tails facing each other on I which have a much larger nonpolar region and C3 Cg smaller polar region float around in the hydrophobic lg interior of the membrane 00 hydrophobichydrophilic What arrangements do phospholipids and detergents tend to form in solution 0 Both phospholipids and detergents have a small highly polarhydrophilic quotheadquot attached to I Glycoliid act a lot like phospholipids in a membrane III What are the physical properties of a typical phospholipid and detergent polarnonpolar an elongated nonpolarhydrophobic quottailquot region 0 In solution detergents form micelles with tails facing inward 0 o Phospholipids prefer to form vesicles which are completely enclosed bilayer bubbles 6 Sb I A vesicle made in the lab for purposes like cosmetics UAV 6 D or drug delivery is called a liposome JQ9 kl El What determines membrane fluidity o The amount of chemical variety there are around 5000 types of lipids found in membranes 0 The abundance of quotkinkyquot unsaturated fatty acids which loosen packing and increase fluidity 0 Temperature like oils and fats higher temperatures increase fluidity III What type of movements do proteins and phospholipids undergo in a membrane 0 Lateral diffusion L A 3quot 53m O Tailflexion O Rotation g V W PrDX Axo o Flipflop P I Usually requires 00 Ta 9mm bod Mnng help of enzymes F9 DV El Where are membranes formed in the cell How is membrane asymmetry created and maintained What are flippases What are scramblases o Membranes are made in the endomembrane system which includes the endoplasmic A Cell Biology Page 1 I l I39IIHIHUIHII IHIIIUIUIIHU IUIIIIHU III LIIH UHIII IIU39V IUIIIHIIIUIUIIH uU IIIIIIHII UIHULHU UIIU maintained What are flippases What are scramblases O Membranes are made in the endomembrane system which includes the endoplasmic reticulum vesicles and Golgi apparatus 0 The way membranesjoin and separate maintains asymmetry O Flippases and scramblases facilitate flipflop and lateral movement The cytosolic side is always the o a h39 a cytosolic side or quotleafletquot oddly The inside of compartments corresponds to the outside of the cell like those weird water tube toys 1 h quot image from lthttpss media cache akOpinimgcom736xbce319bce3195e62c63f0cb63a320bb728302bi03gt The Golgi apparatus has specialized flippases specific to certain lipids III What types of membrane proteins are there and how are they associated with the membrane 0 Membrane proteins carry out most of the actual functions of membranes Receptors for signal transduction Transporters for importing and exporting molecules Linkers for attaching the membrane to the cytoskeleton or extracellular matrix Enzymes that catalyze reactions on the surface of the membrane III Adenylyl cyclase in the G protein signal pathway is an example 0 Membrane proteins can be integral in the membrane or peripheral on the membrane Integral membrane proteins usually contain at least one transmembrane segment which is almost always an alpha helix since alpha helices have the hydrophilic backbone on the inside and the R groups on the outside meaning hydrophobic R groups face the fatty acid interior of the membrane III Hydropathy plots help predict number of transmembrane segments know that the bilayer is about 20 amino acids thick III What are some examples of membrane proteins and their functions Some membrane systems and how they function 0 Photosynthetic reaction center in Rhodopseudomonas viridis 4 proteins three of them are integral First membrane protein to ever be structurally analyzed The integral subunits contain multiple transmembrane alpha helices L and M each have 5 Involves a peripheral cytochrome protein bacterial chlorophyll and a proton pump 0 Membrane proteins help red blood cells also called RBCserythrocytes stay donutshaped Remember quotActin Anchors the Spectrin Skeletonquot Spectrin extends from one bridge junction glycophorin and attachment proteins to the next Actin attaches to bridge junctions and other cellular structures Know that transmembrane glycophorins are integral while spectrin attachment proteins and actin are peripheral O Secretorytransport vesicle budding is an important way membranes help keep everything organized and running smoothly Molecules for export gather near a membrane and then the membrane buds out and forms a vesicle full of them Lots of proteins facilitate this process but we don39t need to really know how 0 Endothelial cells near injured tissues express a membrane protein called lectin that recognizes neutrophils by their glycoproteins and helps them squeeze into the tissue III What is the fluidmosaic model of membrane structure 0 Membranes are mobile lipid bilayers separating two aqueous compartments and providing a Cell Biology Page 2 hydrophobic region for membrane proteins III What are the relative intracellular and extracellular concentrations of K Na Ca2 and Cl 0 Sodium Na calcium Ca2 and chloride Cl39 concentrations are much higher outside the cell I Know the importance Ca2 is low inside the cell so that a tiny increase makes a big difference important since it39s a second messenger I Na is low inside the cell because concentration gradients are useful to have around III We39ll see Na gradients become really important in active transport 0 Potassium K is much higher inside the cell III Lipid bilayers are permeable and impermeable to which types of molecules 0 Permeable to small uncharged molecules steroids dissolved gases water 0 Impermeable to large molecules like sugars and proteins and to any charged or very polar molecule like amino acids or sugars III Compare and contrast solute transport via membrane channels and membrane carriers transporters 0 Channel proteins form a gated aqueous pore that allows particles to pass through when open I They can change conformation from open to closed and regulation affects whether they39re open or closed or strictly speaking whether they spend more time open or closedthey tend to open and close a bit randomly I Channels do not change conformation when particles pass through them III This means many particles can pass at once in singlefile like a line of people going through an open door 0 Carrier proteins unlike channels bind to a molecule change conformation and release it on the other side of the membranethink more like an automated revolving door that won39t stop spinning I Know that these are called transporters in the textbook I They change conformations open to cytoplasm or open to outside the cell independently of whether the solute is there I Carrier proteins can facilitate passive or active transport 0 Both channels and carriers are selective and can be regulated 0 Both typically involve a cylindrical group of alphahelices with hydrophilic amino acid side groups facing the inside of the cylinder III What is an electrochemical gradient How does such a gradient affect transport across a membrane 0 An electrochemical gradient is a gradient where both net chargemembrane potential and a chemical39s concentration are different on the two sides of the membrane 0 The membrane potential and the concentration gradient can combine or compete which affects the direction of passive transport I That is let39s say some hypothetical cell had a low Cl39 concentration compared to its environment which favors Cl39 entering the cell I If the interior of the cell has a net negative charge compared to the outside that favors negative things including Cl39 leaving instead of entering 0 Know that the Nernst equation is used to combine concentration and net charge effects and find the resting normal membrane potential and concentrations III How do active and passive facilitated transport differ What are examples of each 0 Active transport works against quotupquot the concentration or electrochemical gradient I This increases the difference between the sides which is unfavorable I The Na K ATPase is a major example 0 Passive transport works with quotdownquot the gradient by allowing molecules to diffuse into an area with lower concentration I Examples include simple diffusion of C02 out of the cell and the acetylcholinegated ion channel that lets Na enter a nerve cell Cell Biology Page 3 III What are three mechanisms for powering active transport 0 Coupled transport involves transporting something down its gradient which is favorable to generate the energy to move something else up its gradient I Symport moves two solutes the same direction III Example Glucose uptake symport with Na III Many plant protist and prokaryotic cells use H instead of Na for symport I Antiport moves two solutes in opposite directions I Coupled transporters can be occluded or closed to both sides if neither substrate is present 0 ATP hydrolysis powers transport via ATPases or ATPhydrolyzing enzymes which in this case also pump solutes I The Na K ATPase is a very important example know that it pumps 3 Na out for each 2 K in I The Ca2 ATPase pumps calcium ions out of the cytosol and into the sarcoplasmic reticulum in muscle cells or out of the cell 0 Lightdriven transport is most common in prokaryotes I Bacteriorhodopsin changes conformation when photon absorption isomerizes retinal III The conformational change pumps protons out of the cell III This creates a proton gradient used to power ATP synthesis III How does the NaK pump work to maintain osmotic balance 0 Since 3 Na go out and 2 K go in the pump reduces the total ion concentration in the cell 0 If the total ion concentration increased too much osmotic pressure would bring water into the cell the cell would become hypertonic III What is osmosis What is an aquaporin O Osmosis is simply the diffusion of water 0 Water diffuses towards low concentration of quotfree waterquotessentialy towards high concentration of solutes 0 An aquaporin is a channel for efficient passive transport of water III Compare and contrast membrane transport via symport and antiport transporters 0 Both involve one favorable high to low movement and one unfavorable but desired low to high movement 0 Both represent active transport without ATP hydrolysis the energy comes from letting something flow down its gradient 0 Symport moves two solutes the same direction I An example is glucose uptake which moves both sodium ions down the gradienthigh to low and glucose up the gradientlow to high into the cell 0 Antiport moves two solutes in opposite directions I This implies that both of them are abundant on the same side of the membrane III Why do ion channels not function like open pores 0 Being truly open would let everything in and make the membrane too permeable 0 Being very open to their specific solute would allow that solute39s concentration gradient to reach equilibrium and usually disequilibrium is useful because it causes motionchange toward equilibrium III What is membrane potential 0 Voltage resulting from a net charge difference across the membrane one side is positive and one is negative III Compare and contrast the three types of gated ion channels 0 Voltagegated channels open and close according to membrane potential or the accumulation of a charge difference across a membrane I A voltagegated channel lets Ca2 enter a nerve cell which relays a signal causing the release of neurotransmitters into a synapse III At neuromuscularjunctions acetylcholine vesicles fuse with the membrane and release acetylcholine Cell Biology Page 4 o Ligandgated channels open and close according to whether a ligand like a hormone or neurotransmitter is bound I An acetylcholinegated channel lets Na enter a postsynaptic nerve cell to depolarize the membrane triggering many many voltagegated Na channels to open and let in even more sodium ionsan action potential III This makes acetylcholine an excitatory neurotransmitter inhibitory neurotransmitters like GABA and glycine open Cl39 channels to make depolarization even harder O Stressactivated channels are literally pulled open by a mechanical stress III How is ion selectivity determined 0 The wrong charge can be excluded by charged amino acid residues repelling incorrect solutes O Toobig ions are excluded by not fitting 0 Toosmall ions are excluded by not fitting perfectly and being stabilized by the channel III When an action potential reaches a synapse at a muscle cell what happens O In the nerve cell voltagegated Ca2 channels open causing acetylcholine release 0 On the muscle cell acetylcholinegated Na channels open 0 Depolarization causes voltagegated channels to let more Na in the action potential propagates because the charge diffuses throughout the cell 0 Voltagegated calcium channels in the muscle cell39s plasma membrane open themselves as well as calcium channels in the sarcoplasmic reticulum membrane so Ca2 enters the cytosol O The increase in cytosolic Ca2 triggers muscle contraction for animal physbiochem 2 reasons III What does membrane transport have to do with perception of sound Transporting sugar from your gut to your bloodstream 0 Hair cells in the ear tilting bundles bend in response to sound waves and open stress activated ion channels to trigger a signal pathway 0 The intestinal epithelium absorbs glucose by symport with Na I The sodium ionbinding site is nearly always occupied due to the high sodium concentration so the protein is likely to change conformations as soon as glucose binds I This brings glucose from the intestine into the intestinal epithelium and then passive uniport lets glucose continue into the bloodstream III Why does it benefit a cell to oxidize glucose in a stepwise manner 0 When energy is released from glucose a little at a time it can be captured in other energy carriers like ATP instead of released as heat III What cofactors are neededused in glycolysis the citric acid cycle and oxidative phosphorylation O NAD Coenzyme A and FAD are the big ones I NAD and FAD accept electrons and carry them to the respiratory complexes to pump protons into the intermembrane space I CoA carries acetyl units as well as other small molecules between pathways 0 The bridging step pyruvate dehydrogenase complex also needs lipoic acid and thiamine pyrophosphate but don39t worry too much about those III What is the cellular organization of respiration O Glycolysis occurs in the cytoplasm and pyruvate is transported into the mitochondrial matrix 0 The pyruvate dehydrogenase bridging step and TCA cycle take place in the matrix 0 Oxidative phosphorylation occurs withinacross the inner mitochondrial membrane III Glycolysis Where does it happen what are the reactants and products what is the purpose What is meant by energy investment What is meant by energy yield What is substratelevel phosphorylation O Glycolysis occurs in the cytoplasm and turns glucose into two molecules of pyruvate 0 It produces 2 NADH per glucose and 2 ATP net per glucose and breaking glucose into Cell Biology Page 5 pyruvate allows more oxidation and energy capture in the mitochondria 0 Energy investment means 2 ATP per glucose are spent in the beginning of glycolysis 0 Energy yield means 4 ATP per glucose are produced via substratelevel phosphorylation which means that a reaction of a single substrate is directly coupled to the phosphorylation of one ATP as opposed to oxidative phosphorylation using a proton gradient I Energy yield also includes the 2 NADH produced these take electrons to the mitochondria and add to the proton gradient to ultimately power more ATPmaking 0 Know the three stages and be familiar with their steps I Energy investment hexokinase costs 1 ATP phosphoglucoisomerase phosphofructokinase costs 1 ATP I Cleavage aldolase triose phosphate isomerase I Energy yield glyceraldehyde3phosphate dehydrogenase makes NADH and adds a phosphate phosphoglycerate kinase makes 1 ATP2 per glucose phosphoglycerate mutase enolase pyruvate kinase makes 1 ATP2 per glucose III Since this all happens once per pyruvate one glucose produces 2 NADH and 4 ATP in this stage Fermentation Where does it happen what are the reactants and products what is the purpose Compare and contrast alcoholic and lactate fermentation O I seriously don39t think we covered this but it happens in the cytoplasm O The purpose is to regenerate NAD which is normally regenerated by transferring electrons to NADH dehydrogenase complex I in the mitochondrial inner membrane 0 The reactants are pyruvate and NADH and the products are ethanol C02 and NAD in yeast alcoholic fermentation or lactate and NAD in animals lactate fermentation What are monosaccharides disaccharides and polysaccharides What type of bonds link sugar subunits together How do starch glycogen and cellulose differ O Saccharides are sugar monomers usually five or six carbons like glucose so monosaccharides are sugars with only one 56 carbon ring disaccharides are sugjirs with two connected monosaccharides etc 39 I 0 Sugar subunits are connected by glycosidic bonds 0 often called glycosidic linkages I Straight chains have 14 bonds A I Branches are formed with 16 bonds 397 395 L 0 Starch is made of uglucose and has branched amylopectin and coiled parts amylose O Glycogen is made of uglucose and very branched O Cellulose is made of Bglucose and unbranched and lots of hydrogen bonds between chains I Purpose is structural support not energy storage Compare and contrast how plants and animals store energy 0 Plants store energy in starch while animals store energy in glycogen and in storage fats 0 Both plants and animals use polysaccharides for energy storage How are fatty acids stored and transported 0 We didn39t cover this much but fatty acids are integrated into triacylglycerol called quottriglyceridesquot in medicine for transport and storage How and where is acetyl CoA made What are two main sources of acetyl CoA O Acetyl CoA is made from pyruvate by the pyruvate dehydrogenase complex and from fatty acids by beta oxidation which means oxidatively cleaving off twocarbon units from a long fatty acid chain 0 Both these processes occur in the mito matrix 0 Know that acetyl CoA is an quotactivatedquothighenergy A carrier because the thioester bond is unstable so C energy is released when it39s broken 5 Citric acid cycle Where does it happen what are the enzymes substrates and products what is the point of the cycle How is the citric acid cycle related to the electron transfer system What is oxidative phosphorylation Cell Biology Page 6 O The citric acidTCAKrebs cycle occurs in the mitochondrial matrix 0 The point is to oxidize 2carbon units from acetyl CoA and capture electrons in NADH and FADH2 in order to drive oxidative phosphorylation later I The TCA cycle is kind of the beginning of the electron transfer system since electrons are transferred to activated carriers which will transfer them to the complexes 0 There are 8 steps to know each step39s substrate is the previous step39s product I Use the mnemonic quotCitric s Krebs39 Starting Substrate For Making Oxaloacetatequot citrate synthase I Oxaloacetate and Acetyl CoA gt Citrate and CoA aconitase I Citrate gt lsocitrate isocitrate DHase I lsocitrate and NAD gt aketoglutarate NADH H C02 oc ketoglutarate DHase I dketoglutarate NAD CoA gt Succinyl CoA NADH H C02 succinyl CoA synthetase I Succinyl CoA GDP Pi gt Succinate CoA GTP III This is named for the reverse reaction succinate DHase I Succmate FAD gt Fumarate FADH2 III Fumarate and FADH2 are made in the same stephepfu alliteration fumarase I Fumarate gt Malate malate DHase I Malate NAD gt Oxaloacetate NADH H I There are four DHases or dehydrogenases each reduces a cofactor III This means half the enzyme names to know are substrate dehydrogenase III What is gluconeogenesis What controls whether a cell does gluconeogenesis or glycolysis O Gluconeogenesis is making glucose from pyruvate pretty much by backwards glycolysis O The energy status of the cell determines which process happens I If there39s enough energyATP gluconeogenesis happens I If there39s not enough energyATP glycolysis happens so the TCA cycle and oxidative phosphorylation can make more ATP III Mitochondria structureknow the function and location of the following outer membrane intermembrane space inner membrane matrix mitochondrial genome mitochondrial ribosomes 0 Outer membrane contains porins that let anything with a molecular weight less than 5000 into the inner membrane space IMS 0 IMS between the two bilayer membranes chemically very similar to cytosol because of the porins 0 Inner membrane way less permeable than outer membrane contains electrontransport complexes and ATP synthase 0 Matrix the inside of the mitochondria surrounded by the inner membrane basic and negatively charged compared to the cytosol O Mitochondrial genome circular doublestranded DNA found in the matrix codes for some but not all of the genes used for mitochondrial function I Very small in human mitochondria larger in many plants I Contains about 2 of its bacterial ancestor39s genome I Codes for rRNA tRNAs and some subunits of inner membrane enzymes III The mitochondrion has to import ribosomal proteins aminoacyltRNA synthetases DNA and RNA polymerases and other inner membrane enzyme subunits from the cytoplasm O Mitochondrial ribosomes found in the matrix provide evidence that mitochondria originated from aerobic bacteria especially because the ribosomes are more like bacterial ribosomes than eukaryotic ribosomes III What is oxidative phosphorylation Why is it a chemiosmotic process 0 Oxidative phosphorylation is when ATP is made using the power of the H gradient created using redox reactions 0 It39s a chemiosmotic process because it39s powered by an electrochemical gradient Cell Biology Page 7 III Define oxidation reduction and redox pairs 0 Reduction means the gain of electrons while oxidation means the loss of electrons I Remember quotLEO says GERquotlosing electrons is oxidation gaining electrons is reduction I For example in the reaction Fe2 gt Fe3 e39 Fe2 is oxidized because it loses an electron 0 Since counting electrons or calculating oxidation states is a pain organic chemistry defines reduction and oxidation in a more visible way I Reduction is gaining hydrogen atoms andor losing oxygen atoms or quotassociationquot with oxygen like going from a double bond to a single bond I Oxidation is losing hydrogen atoms andor gaining oxygen atoms or quotassociationquot with oxygen 0 A quotredox pairquot is comparable to a conjugate acidbase pair identical molecules except one is oxidized and one is reduced I Examples include NAD and NADH and FAD and FADH2 III Electron transport chain Where is it located What are the inputs and products What are the components How does each component work to generate a proton electrochemical gradient across the inner membrane 0 O 0 Located across the inner membrane Includes NADH dehydrogenase complex I cytochrome bc1 complex III and cytochrome oxidase complex IV plus cytochrome c and ubiquinoneCoQQ mobile electron carriers Inputs NADH FADH2 Products NAD FAD NADH dehydrogenase oxidizes NADH and channels protons to the intermembrane space I The electrons get passed to Q Q 2H 2 e39 gt QHz I Moves 4 H 2 from NADHH being oxidized 2 from 0339 becoming QHz Cytochrome bc1 accepts electrons from QHz and passes them to cytochrome c the other mobile electron carrier know that it carries single electrons I It also pumps 4 H part of the quotQ cyclequot I Can also accept electrons from complex II or succinate dehydrogenase which oxidizes FADH2 Cytochrome oxidase accepts an electron from cytochrome c and reduces 02 to H20 which takes 2 H from the matrix This means 10 H per NADH or 6 H per FADH2 get pumped III What is the role of NADH dehydrogenase complex 0 Regenerates NAD passes electrons to the next component Q and pumps some protons III What are three types of electron carriers 0 O O Quinone carries 1 or 2 Ironsulfur FeS centers carry 1 Cytochromeheme groups carry 1 I Cytochromes are small proteins holding heme groups I Heme groups are big flat organic molecules holding a metal ion that gets oxidized and reduced III In which two ways does e transfer results in H pumping 0 An electron carrier like ubiquinone can pick up a proton from one side and release it on the other I This happens in the cytochrome bc1 complex due to redox reactions Conformational changes in an enzyme cause it to pick up a proton on one side and release it on the other I This happens in the NADH dehydrogenase and cytochrome oxidase complexes due to changes in affinity for protons III What is the role of cytochrome oxidase O Passes an electron from cytochrome c to 02 after this happens 4 times water is produced Cell Biology Page 8 What is the role of ATP synthase 0 Utilizes the proton gradient to phosphorylate ADP 0 Makes 8090 of the cell39s ATP In addition to ATP formation what else is the proton gradient used for O Symport of pyruvate and inorganic phosphate into the matrix What mitochondrial behaviors have been observed 0 Shapeshifting fission division and fusion joining Are proteins that function in the mitochondria exclusively encoded by the mitochondrial genome o Nomany important mitochondrial proteins are encoded by the nuclear genome synthesized in the cytoplasm and imported into the mitochondrion Chloroplast structure give the role and location of the following outer membrane intermembrane space inner membrane stroma thylakoid membrane thylakoid space chloroplast genome chloroplast ribosomes o This question and the next are answered in the drawing below Compare and contrast the position of the ATP synthase where ATP is generated and the permeability of the inner membrane to ATP in mitochondria and chloroplasts good review for the final lcn OMAR c 5r w Space ENE membrane i as Cienome 439 K3 S me5 o The thylakoid membrane is derived from the inner membrane thylakoids are a lot like pinchedoff cristae mitochondrial folds o Thylakoid stacks are called grana 0 ATP synthase is in the inner membrane in mitochondria and the thylakoid membrane is chloroplasts it quotpointsquot pumps protons to the matrix or stroma o couldn39t find much information on inner membrane permeability to ATP but since so much ATP is used in the stroma of the chloroplast for carbon fixation the chloroplast probably doesn39t need to export ATP like the mitochondrion does What is photosynthesis What happens in the light reactions versus the dark reactions 0 Photosynthesis is the conversion of light energy to chemical energy stored in carbohydrates 0 The light reactions capture energy by reducing carriers the dark reactions use energy from activated carriers to fix carbon dioxide grab it and make the carbon bond to other carbons What is chlorophyll and happens when light shines on it o Chlorophyll is a pigment molecule that can be excited by red or blue light and pass electrons to carriers What is the endosymbiont hypothesis 0 Chloroplasts and mitochondria originated as freeliving bacteria that got absorbed into cells 0 Over time these prokaryotes and their host cells became interdependent Be familiar with the methodology and applications of the following techniques FRAP patch clamp recording membrane protein isolation o FRAP stands for Fluorescence Recovery After Photobleaching which evaluates mobility of lipids by lateral diffusion sliding past each other I Tag a region of lipids with a fluorescent dye bleach it with a laser and measure amount of fluorescence in the bleached area over time I Fluorescence in that area increases due to diffusion of lipids as equilibrium in this Cell Biology Page 9 case evenrandom distribution of bleached lipids around the whole membrane is approached I Faster recovery more mobility 0 Patch clamp recording is used to isolate a piece of a cell membrane containing an ion channel and make it a sort of switch in a circuit I ons travel through the channel due to the flow of electrons through the circuit I Changes in voltage are recorded and analyzed to measure the rate of ion flow through thatchannel O Membrane protein isolation I Peripheral proteins are isolated using a salt solution to disrupt the hydrogen bonds and ionic attractions that keep them attached to integral proteins I Integral proteins are isolated by disrupting the membrane with a detergent III Detergent molecules are amphiphilic a great example is sodium dodecyl sulfate SDS which has a very nonpolar twelvecarbon chain attached to a charged sulfate group III Ionic detergents disrupt the membrane so much that they often denature integral proteins III Nonionic detergents those with a polar uncharged quotheadquot rather than a charged one are gentler and better at keeping the protein in its shape by mimicking the chemical environment of the membrane and making a mixed micelle illustrated to the left 0 Pink polar exposed parts of protein 0 Purple nonpolartransmembrane helices 0 Orange nonpolar detergent tails protecting the transmembrane helices from water 0 Blue polar detergent heads exposed to water New after Tuesday update III What is a photosystem What are the two parts Where in a photosystem is energy transported and where are electrons transported What is the special pair How are the electrons donated by the special pair regenerated in photosystem II and photosystem I 0 Each photosystem contains chlorophyll and proteins in the thylakoid membrane I The antenna complex harvests light energy and transfers that energy not an electron to the special pair I The reaction center39s quotspecial pairquot of chlorophyll molecules receives energy from the antenna complex and shoots an electron to an acceptor protein I There are many chlorophyll molecules but only the special pair actually sends an electron into electron transport the others just capture light to excite the special pair 0 Photosystem 39s lost electron is replaced with one from water 0 Photosystem 39s lost electron is replaced with one from Photosystem II I The electron is transferred through electron transport not directly III What is charge separation O The excited electron is transferred to an electron transporter giving it a negative charge and the special pair a positive charge III What is the path of electrons during noncyclic photophosphorylation 0 Water photosystem II plastoquinone cytochrome b5f complex plastocyanin photosystem I ferredoxin NADP III What is the path of electrons during cyclic photophosphorylation O Cytochrome b5f complex plastocyanin photosystem I ferredoxin cytochrome b5f complex 0 No NADPH is madethe whole point is to pump protons to make some ATP III What is the role of ferrodoxin NADPreductase 0 Makes NADPH from NADP O NADPH is just like NADH with an extra phosphate group used to direct it to enzymes Cell Biology Page 10 responsible for biosynthesis How does electron transport generate a proton gradient in chloroplasts o Electrons are taken from water in the thylakoid space which frees protons there 0 The cytochrome b5f complex pumps protons into the thylakoid space Carbon fixation Where does it happen what are the inputs and products what is the point 0 Occurs in the stroma O 3 C02 9 ATP 6 NADPH gt glyceraldehyde3phosphate 9 ADP 8 P 6 NADP O Traps carbon from the atmosphere to turn into food molecules What is Rubisco 0 Huge enzyme 16 subunits responsible for attaching C02 to ribulose15bisphosphate 0 Also the most abundant protein on the planet Give three uses plant cells have for glyceraldehyde 3phosphate 0 Making starch for energy storage in the stroma o Entering the glycolysis pathway to make pyruvate for the TCA cycle glycolysis in cytoplasm TCA in mitochondria just like in animal cells 0 Conversion to other metabolites like sucrose in the cytoplasm Cell Biology Page 11
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