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Lecture Notes for BIO 1

by: Pooja Sheth

Lecture Notes for BIO 1 01:119:115

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Pooja Sheth

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Here are lecture notes for some of the chapters from Dr. Bendaoud's class.
General Biology
Professor Bendoud
Class Notes
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This 35 page Class Notes was uploaded by Pooja Sheth on Sunday October 16, 2016. The Class Notes belongs to 01:119:115 at Rutgers University taught by Professor Bendoud in Fall 2014. Since its upload, it has received 7 views.


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Date Created: 10/16/16
CHAPTER 7:Membrane structure and Function(7.1-7.5) 7.1: Structure of cellular membrane IMP FEATURES: 1)Phospholipids: Main component of membranes -Amphipathic: Hydrophobic tails+Hydrophilic head. -Hydrophobic interactions : form bilayers FIG 7.2 2)Fluid Mosaic Model: Membrane = Fluid structure + “mosaic”of various proteins. -must be fluid to work properly— like salad oil. FIG 7.3 3)Proteins: Membrane Proteins:TYPES 1) Peripheral proteins: on surface of membrane —only hydrophilic 2) Integral proteins: inside membrane -If span membrane:Transmembrane protein -Internal hydrophobic/external hydrophilic regions. FIG:7.3 and 7.6 FIG:7.7 4)Carbohydrates: (2 forms): 1)Glycoproteins attached to protein AND 2)Glycolipids attached to lipid. -IMP in Cell-Cell Recognition. (FIG 7.3). -Do membrane proteins move? Experiment: Cells fused after an hour—>Proteins had mixed. Conclusion: at least some membrane proteins can move with in plane of FIG:7.4-3 A)Fluidity of membranes: Fluidity depends on : 1)Temperature-if too cold—>solidifies 2)Fatty acid length: shorter —> more fluid 3)Fatty acid saturation :unsaturated—> more fluid 4)Cholesterol: at warm Temp—> stabilize membrane fluidity. But at low temp—> hinders solidification. FIG 7.5. B)Mosaic: -Protein in mb—> form pattern (tiles in a mosaic) -some held in place by cytoskeleton -other move laterally in fluid -Pattern constantly changing with layer -cannot flip-flop between layers. 7.2: Membranes structure:selectively permeable -Membrane regulates movement of molecules in/out the cell using: 1)Lipid bilayer permeability 2)Transport proteins. 1)The permeability of the Lipid bilayer -Hydrophobic molecules (non polar): —> Dissolve in—cross the lipid bilayer -Hydrophilic molecules(ions and polar molecules): —> Do not dissolve in—do not cross membrane easily. 2)Transport proteins: Allow passage of hydrophilic substances across membrane. 2 Types: A)Channel proteins-Allow a specific molecule or ion to cross the membrane. -1)Aquaporins facilitate the diffusion of water -2)Ion channels facilitate the diffusion of ions. -(some are gated channels,open or close). (hydrophilic tunnel, Aquaporins specific of water). B)Carrier proteins- change in shape, translocate molecules across the membrane, and are specific. FIG:7.14 7.3:Passive Transport -Diffusion of a substance across a membrane -No energy investment. -NET movement always occurs: -down concentration gradient -From high concentration to low concentration. -At dynamic equilibrium—> no net movement but molecules still moving evenly in both directions. ~Membranes Transport (2 main types of transport) 1) Passive (7.3)-No energy (ATP) A) Simple diffusion B) Osmosis C) Facilitated diffusion 2) Active(7.4)-Needs energy or (ATP) FIG:7.16 ~A)Simple diffusion: Diffusion of substance across the lipid bilayer. What substances can diffuse: 1)Gases: O2,CO2, and N2. 2)Small, non polar molecules -hydrophobic substances—includes hydrocarbons. 3)Small polar, uncharged molecules (hydrophilic)—including H2O-small enough to slip past fatty acid tails. ~B)A special case of Diffusion:Osmosis -Osmosis: diffusion of water across a selectively permeable membrane -Water diffuses: -From lower to higher solute concentration -until the solute concentration is equal both sides. OR can be described as: -From higher to lower concentration of H2O. ~C)Facilitated Diffusion -A Diffusion aided by proteins -No energy needed -molecule move: down concentrated gradient -What substances use it? 1)Large Molecules: to big 2)Polar Molecules: hydrophilic (ex.glucose) 3)Ions: charged and therefore, hydrophilic (ex. H+ can’t cross lipid bilayer). ~ Water Balance of cells without cell walls. -Tonicity: ability of a solution to cause a cell to gain or lose water. -Isotonic solution: solute concentration -outside cell = inside the cell ; No net movement. -Hypertonic solution: solute concentration Outside cell > inside the cell (cell loses water) -Hypotonic solution: solute concentration Outside cell < inside the cell (cell gains water). ~Water Balance of cells with cell walls. -In hypotonic solution -cell swell ; the cell is turgid (firm). —>movement of water in cell stops —> normal healthy state. -In isotonic solution: cell is flaccid (limp) -In hypertonic solution: cell lose water: membrane pulls away from cell wall; plasmolysis. FIG 7.12 7.4: Active Transport -Uses energy(ATP) - to move solutes against their gradients - specific transport proteins required - Allows materials to be stockpiled by cell - Allows cell to maintain concentration gradients that differ from their surroundings - EX: The sodium-potassium pump - pumps 3 Na+ out and 2 K+ in —> establishes electrical gradient. FIG 7.16 7.5: Bulk Transport: Exocytosis And Endocytosis - Always requires energy-ATP - Types of active transport( but not carrier mediated) - Transport via vesicles - Transport Large molecules such as polysaccharides and proteins - 2 TYPES: 1)Exocytosis AND 2)Endocytosis 1)Exocytosis: In this: -Vesicle containing wastes or secretory products -Vesicles migrate to the membrane. -Fuse with plasma membrane -Macromolecules released outside the cell -Secretory cells use exocytosis to export their products. 2)Endocytosis: -Macromolecules taken into cell. -Forms vesicles derived from plasma membrane 3 TYPES of endocytosis: A)Phagocytosis (“cellular eating”) B)Pinocytosis (“cellular drinking”) C)Receptor-mediated endocytosis. A)Phagocytosis: -A cell engulfs- - large solid particles -use folds of plasma membrane -forms a vacuole -Vacuole pinches off inside cell -then fuses with a lysosome -digest the particle in.FIG 7.19. B)Pinocytosis: “cell drinking” -Takes in fluid + dissolved materials. -Forms small fluid-filled coated vesicles. -Pinocytosis is unspecific. C)Receptor-mediated endocytosis -Receptor proteins in membrane -molecules cluster in coated pits -form coated vesicle. -Is specific -ex: cholesterol uptake from blood by mammalian cells. Chapter 8: (8.1-8.4)- AN INTRODUCTION TO METABOLISM 8.1:Metabolism -Sum of all chemical reactions of an organism. -Regulated to maintain homeostasis -An emergent property of life—> arises from orderly interactions between molecules. ~Metabolic Pathways~ -A metabolic pathway begins with a specific molecule and ends with a product. -Each step is catalyzed by a specific enzyme. FIG:8.UN01 2 Types of Metabolic Pathways: 1)Catabolic pathways— breaking down complex molecules to simpler ones. -Release energy. -Ex. Cellular respiration= breakdown of glucose. 2)Anabolic Pathways— build complex molecules from simpler ones. -Needs energy -Ex. synthesis of protein from amino acids. ~Forms of energy~ -Energy= Capacity to cause change. -Kinetic E= Energy of Motion. -Potential E= Stored Energy—> has not yet been used. -Heat(Thermal energy)= Random movement of atoms or molecules. Ex: A diver has more potential energy on the platform than in the water. Diving converts potential energy to kinetic energy. ~The law of thermodynamics~ Thermodynamics-study of Energy transformations. 1)First Law of thermodynamics -E. cannot be created or destroyed. -But can be converted from one form to another. 2)Second Law of thermodynamics: Every E. transfer or transformation increases the entropy (disorder) of the universe. -Entropy(S): a measure of disorder. ~Entropy~ 1)Food is organized E. -stored chemical bonds -low entropy and is usable 2)Heat: disorganized E. -less-usable E. -cannot perform work -disperses into environment - -high entropy Entropy continuously increasing in universe. ~Biological Order and Disorder~ -Light E. enters an ecosystem and heat E. exits. -E.conversion never 100% efficient -car engine—> 20-30% efficient,rest is heat. -cells—> 40% efficient,rest is heat. -Total E. in universe is constant but -Total E. available to do work is decreasing over time. ~Energy Needs In Cells~ -Ultimate source of E.—> Radiant E(sun) -Cell needs E to do: 1)Mechanical work (movement) 2)Transportwork (active mb transport) 3)Chemical work (breaking bonds) -Forms of E. in cells 1)Potential E: stored in covalent bonds of molecules 2)Kinetic E: released when bonds are broken. 8.2:Free-Energy change of reactions in cells -Free E (G)= amount of E available to do work -Enthalpy(H)=total bond E in system = total potential E. -Entropy(S)=entropy -Temperature(T)=in kelvin. G can’t be measured, but changes in G: deltaG (∆G) can -ΔG and ΔH in KJ/mole units (E per molecular amount of a chem substance) -ΔS in KJ/K units -T in K. ~Free Energy Change, ΔG -Use equation to predict if chem. reactions release E or require E input. -2 Types of reactions: 1)Exergonic reactions (“E outward”) -Release energy 2)Endergonic reactions (“E inward”) -Require energy 1)Exergonic reactions: -Potential E in reactants > potential E in products -Free E in initial state> Free E (G) in final state —>ΔG is a negative number(loss of free energy) -Energy is released: R—> P+E -Spontaneous (but not instantaneous)—Ex. catabolic reactions- breakdown -Large molecules broken down into smaller ones. 2)Endergonic reactions -Potential E in reactants < potential E in products -Free energy in initial state < Free E(G) in final state —>ΔG is a positive number (gain of free E) -E is gained: R+E—> P -Not spontaneous :require addition of E to proceed Ex.anabolic reactions -synthesis -Simpler substances combined to form complex substances (for storage of E). ~Exergonic/Endergonic Reactions Summary~ Exergonic rxns: -Release free E -Spontaneous - (-ΔG) - Catabolic - Breakdown Endergonic rxns: -Absorb free E -Non-spontaneous - (+ΔG) - Anabolic - Synthesis FIG: 8.6 8.3 ATP Powers Cellular Work -Cells need E for endergonic reactions -Use Energy coupling: -Exergonic rxns drive (coupled to) Endergonic rxns -Often the exergonic rxn. is: breakdown of ATP -In cells most En. Coupling mediated by ATP -ATPused by cells to store E—> “high energy” ~The Structure and Hydrolysis of ATP -ATP(adenosine triphosphate) is made of: -Ribose(5-C sugar), -Adenine(nitrogenous base) -3 Phosphate groups FIG 8.9 ~Hydrolysis of ATP~ FIG 8.9 ~How ATP Drives chemical work~ -ATP drives endergonic rxns by phosphorylation -Transfer a phosphate group to the reactant -Reactant now called: phosphorylated intermediate FIG 8.10b. ~Free-energy change for coupled rxns~ : FIG 8.10c. ~How ATP Drives Transport and Mechanical work~ :FIG 8.11 ~The Regeneration of ATP~ : ATP cycle : FIG 8.12 8.4. Enzymes -Exergonic rxns. are spontaneous —> No E. needed but not fast enough for cell -Need catalyst Enzymes -Catalyst: chemical speeds up a rxn. without being consumed by the rxn. -Enzyme: catalytic protein. FIG 8.UN02 ~Activation E. Barrier of An Exergonic Rxn~ -Enzymes speed up rxns. by lowering E. barriers: -Activation E( Ea): Initial E needed to start a rxn. FIG 8.13 ~Enzymes Biological Catalysts~ 1)Speed up rate of chemical rxns. in cells 2)Not used up in process(reused) 3)Lower Ea of the rxn by 4)Bringing together reactants 5)Weaken chemical bondssometimes 6)Most names end in -ase 7)Cannot cause rxn. to happen that wouldn't have happened anyway. only speed it up. ~Effect of an enzyme on Ea~ : FIG 8.14 ~Substrate Specificity of Enzymes~ -Have active site: cleft or groove for substrate binding -Substrate: reactant that an enzyme acts upon -Are substrate specific: -Form Enzyme-Substrate complex -Induced fit- change of shape after binding of substrate for better fit: facilitate breaking of bonds. FIG 8.15. ~Effects of local conditions on Enzyme Activity~ -Effects of Temp and pH -Enzymes operate at Optimal (best) Tempand pH -Each enzyme has an optimal Temp—> to function ex. Human—> optimal Temp (35- 40 degree Celsius) -Temp and pH changes—> destroy shape (3D structure) -Low Temp- enzymatic reaction —> slow or not at all. -High temp-even short exposure—> denature enzymes. ~Environmental Factors Affecting Enzyme Activity~ FIG:8.17 ~Enzyme Helpers: Cofactors~ -enzyme cofactors can be : 1)Inorganic — Nonprotein —often metals 2)Organic -called coenzyme -include vitamins. ~Enzyme Inhibition~ 1)Reversible inhibition: -Competitive inhibitors bind temporarily to the active site competing with the substrate -Noncompetitive inhibitors bind to another part of an enzyme, causing change shape of active site. FIG 8.18 2)Irreversible Inhibition: -Permanent inactivation or destruction. -bind to active or other sites -Ex. toxins,poisons, pesticides, and antibiotics. CHAPTER 9:Cellular Respiration and Fermentation FIG:9.2 ~Cellular Respiration: A catabolic Pathway~ -Digestive system—> break down food -Carbohydrates Simple Sugars -Proteins ———-> Amino Acids ——-> Bloodstream—>cells—>Cellular Resp. -Fats Glycerol+fatty Acids -Catabolic Pathways—> release stored E in Food . -Using e-transfer —> e- move —> E is released. -E from e- used to make ATP. 9.1:Redox rxns: Oxidation and Reduction -Redox rxns: transfer e- between reactants Xe- + Y —> X + Ye- -Xe- becomes oxidized to X - Y becomes reduced to Ye- Oxidation: loss of e- (one or more)—> is oxidized Reduction: gains e- —> is reduced FIG 9.UN02 ~Oxidation and Reduction~ -Reducing agent: e- donor—> oxidized -OXIDIZING AGENT:e- acceptor—> reduced. -Molecule can be oxidized by losing a H -Molecule reduced takes the H -H takes e- with it and transfers E to the H acceptor -NAD+(nicotinamide adenine dinucleotide)= Known H acceptors. ~NAD+ as an e- shuttle~ -Oxidized(NAD+) <—> reduced (NADH) -NADH has stored E used to make ATP. -Dehydrogenases enzymes: 1)Remove pair of H(2 e- & 2 protons)from substrate—>oxidation 2)Deliver 2e- and 1 proton (H+) to NAD+ —>NADH—>1 H+ released in solution FIG 9.UN04 ~Cellular Respiration~ 1)Converts : -Chemical E in bonds of nutrients—> chemical E in ATP—> E used for cell work. 2)Can be: Aerobic: uses O2 OR Anaerobic:does not require O2 3)Occurs in all cells: 1)Prokaryotes and 2)Eukaryotes. ~Aerobic Respiration Of Eukaryotes~ -Simplified eqn. of cellular Respiration: C6H12O6 + 6O2 → 6CO2 + 6 H2O + E(in ATP) -Redox rxns.—> transfer of e- from nutrients -Glucose oxidized— H removed, forms CO2 -O2 is reduced— H added, forms H2O -Catabolic rxn: Exergonic—> delta G is -686 kcal/mol. -About 30 steps—> each catalyzed by an enzyme. ~Aerobic respiration of eukaryotes~ -1)Glucose: common starting material for most cells and in some cells is the only material. Ex. brain: only use glucose (can’t store it)—> drop in blood sugar—> fatal. 2)Amino acids, gylcerol, fatty acids, and simple sugars : other sources of E. -Fed into cellular respiration, but at different points of process. ~The stages of cellular respiration: A preview~ -4 main stages: 1)Glycolysis : Glucose—> 2 pyruvates -in cytoplasm. 2)Oxidation of Pyruvate to acetyl CoA -in matrix of mitochondria 3)The citric acid cycle: pyruvates—>CO2 completes breakdown of glucose -in matrix of mitochondria. 4)Oxidative Phosphorylation: most of the ATP synthesis -in inner membrane of mitochondria. -FIG 9.6-3. ~ATP synthesis~ -For each glucose—> cell makes up to 32 ATP. -2 ways: 1)90% of ATP—> by oxidative phosphorylation 2)10% of ATP —> substrate-level phosphorylation in glycolysis+ citric acid cycle. FIG 9.7 ~9.2 Glycolysis~ -Glycolysis “sugar splitting” -Glucose—> 2 pyruvates -Glucose enters cell: via GLUT1 -Location : cytosol -2 major phases: 1)Energy investment phase:uses ATP AND 2) Energy payoff phase: makes ATP -Glycolysis occurs whether or not O2 is present. FIG 9.UN06 ~E Investment Phase: Need ATP Endergonic~ FIG 9.9a ~E Payoff Phase: Need ATP Exergonic~ FIG 9.9b ~Glycolysis Summary: Glucose—> 2G3P—> 2 pyruvate. FIG 9.8 ~2 Pyruvate enter the mitochondrial Matrix~ 1)Through outer membrane:diffuses -small pores—> concentration gradient 2)Across inner membrane: active transport -carrier protein—> needs E. FIG 6.17a ~9.3 Oxidation of Pyruvate to Acetyl CoA~ -Links glycolysis to the citric acid cycle. FIG 9.UN07. ~Oxidation of pyruvate to Acetyl CoA~ -Pyruvate converted to acetyl Coenzyme A -Catalyzed by pyruvate dehydrogenase. FIG 9.10 ~Oxidation of Pyruvate :Summary~ 2 pyruvate 2 acetyl CoA (Did we use AP in this phase?—> NO) + 2 NAD+ ——> + 2NADH + 2CoA + 2H+ + 2CO2 FIG: 9.11a ~9.3 The citric Acid cycle(CAC): Also called Krebs cycle. FIG: 9.UN08 -8 steps: FIG: 9.12-8. Summary: -Glucose is completely oxidized to CO2 -1 Glucose = 2 turns -2 turns generate: - 4 CO2 -2 ATP -6 NADH -2 FADH2 FIG: 9.11b. ~9.4 Oxidative Phosphorylation~ FIG: 9.UN09 -End of 3 stages of aerobic respiration: -Only 4 ATP produced(2 in glycolysis + 2 in CAC) -Most E from original glucose molecule is stored: -In form of high E e- in NADH and FADH2 -their E used to synthesize more ATP through 1)Electron transport chain(ETC) AND 2)Chemiosmosis -Oxidative Phosphorylation = ETC + Chemiosmosis. 1)Pathway of Electron Transport Chain(ETC) -ETC—> in inner membrane of mitochondrion -(e-) pass down chain of 4 carriers by redox reactions. -Carriers grouped in 4 complexes: I, II, III, and IV - I,III and IV also pump H+ from matrix to inter membrane space. -ETC Free E change FIG: 9.13. -(e-) transfer in ETC causes proteins to pump H+ to the inter membrane space: Create H+ gradient. FIG: 9.15a 2)Chemiosmosis: The energy- coupling mechanism use ATP synthase -Chemiosmosis= use of energy in a H+ gradient to drive cellular work. -ATP synthase= A Molecular Mill: enzyme in inner membrane(mb). -H+ gradient: H+ diffuse through back to matrix : causes rotation. -Exergonic flow of H+ -Provides E for phosphorylation of ATP - ADP + P1—> ATP. FIG:9.14 -Oxidative Phosphorylation: FIG- 9.15. ~An accounting of ATP production by ETC~ -Glucose—>NADH or FADH2 —> electron transport chain—> proton-motive force—>ATP 1)Each NADH: -in matrix yields 2.5 ATP -in cytosol only yield 1.5 ATP (E must be used for NADH transport in matrix) 2)Each FADH2: -In matrix yields 1.5 ATP. ~Summary of Aerobic Respiration: FIG 9.16. ~Cellular Respiration in Prokaryotes (Bacteria)~ -No nucleus, no membrane- bound organelles -No mitochondria —> Aerobic respiration in cytosol —> ETC in plasma membrane -All same phases as eukaryotes -But more ATP produced (all NADH in the cytosol). (Lecture 9) CHAPTER 10: PHOTOSYNTHESIS (10.1-10.3) 10.1:Photosynthesis converts light energy to the chemical energy of food. 10.2: The light reactions convert solar energy to the chemical energy of ATP and NADP 10.3: The Calvin Cycle uses the chemical energy of ATP and NADP(e- carrier) to reduce CO2 to sugar. *Plants have mitochondria-> ATP* ~Photosynthesis is opposite of cell respiration. ~Photosynthesis- process that converts solar energy into chemical energy. -Photoautotrophs are producers of the biosphere, using sunlight to produce organic molecules from CO2 and other inorganic molecules. -Almost all heterotrophs including humans, depend on photoautotrophs for food and O2. 10.1-In chloroplasts, photosynthesis converts light energy to the chemical energy to food. Fig: 10.4 ~CO2 enters and O2 exits the leaf through stomata (microscopic pores) in epidermal layer of leaf. ~Chloroplasts are found mainly in mesophyll cells, which sit between outer and inner epidermal layers. ~Chloroplasts contain chlorophyll (in thylakoids-which are arranged in stacks called grana). ~Chlorophyll captures light energy. ~Plant doesn’t photosynthesize at night, so stoma closes off. ~Chlorophyll gets excited and photosynthesis process begins! FIG:10.5-H2O is spent in H2 + O2 ~Hydrogen e- are incorporated into sugar molecules. ~Oxygen + H2O released as by-product. Reactant: 6CO2 12H2O Product: C6H12O6 H20 6O2 6CO2 + 12 H2O + light energy ——> C6H12O6 + 6O2 + 6H2O (CO2 gets reduced to C6H12O6) (H2O gets oxidized to O2) ~Photosynthesis is REDOX process. -Photosynthesis reverses direction of e- flow compared to respiration - H2O oxidized + CO2 reduced. -While Respiration is exergonic, Photosynthesis is endergonic; the energy boost is provided by light. ~2 stages of Photosynthesis~ Fig: 10.6 1)Light reaction (in Thylakoids) -splits H2O -releases O2 -reduces NADP+ to NADPH -generates ATP from ADP -Photophosphorylation 2)Dark reaction—makes food. (Calvin cycle)(in stroma of fluid between grana) -forms sugar from CO2 : carbon fixation -Oxidizes NADPH to NADP + (e-) -Hydrolyzes ATP to ADP and P ~10.2~ FIG: 10.11 ~Thylakoid membranes sit in stacks called grana; contain chlorophyll and enzyme -Chlorophyll a(alpha) (CH3) is main photosynthetic pigment. -Accessory pigments, such as chlorophyll “b”(beta), broaden spectrum used for photosynthesis. -Accessory pigments called carotenoids-(make colors of plants) absorb excessive light that would damage chlorophyll. ~When a pigment absorbs light (photon), it goes from a ground state to an excited state. -Photons are given off= fluorescence (absorbs at one wavelength+ emits at another) -Emitted light represents energy that can be captured by an acceptor (e.g.photosyn) -Chlorophyll “b” absorbs at ~450-500 nm + 600-650 (yellow-green) -Chlorophyll “a” absorbs at 400-450 nm + 600-700nm (blue-green) (blue light emitted as green light) ~The Photosystem in Thylakoid membrane (fig 10.13)~ -In each photosystem: -Light harvesting pigment complexes composed of proteins, carotenoids+ chlorophyll beta to help enhance absorption of light (photons) -transferring their energy to chlorophyll “a” in reaction center at the core of photosystem. ~There are 2 types of photosystems(10.14) 1)Photosystem I (PSI)-which evolved first —is best at absorbing wavelengths of ~700nm -reaction center containing chlorophyll “a” is called p700 2)Photosystem II (PSII) is best absorbing wavelength ~680nm. -reaction center containing chlorophyll “a” is called P680. P700+ P680 are identical chlorophyll “a” molecules but association w/diff. Protein molecules in thylakoid membrane provide light. -Some organisms such as purple sulfur bacteria have PSI but not PSII -cyclical e- flow is thought to have evolved between linear e- flow -Cyclical e- flow uses PSI and produces ATP, but no NADPH -No O2 released -Cyclical e- flow generates surplus of ATP, satisfying higher demand in calvin cycle. FIG:10.4 -Linear e- flow in plants is primary pathway involving both PSI and PSII, producing ATP + NADPH that can be used in Calvin cycle. -PSII : P680 is strong oxidizing agent 1)A photon of light hits pigment complex boosting e- to higher level -photon energy passed among other pigment molecules until it excites 2 e- in P680. 2)e- are transferred from P680 which becomes P680+ oxidized + an electron acceptor 3)H2O is split by enzymes : two e-, 2H+, + an O atom released - e- transferred to P680+ -2H+ released into thylakoid space -O atom combines w/another “O” atom from another process = O2 (byproduct) (Each e- falls down an e- transport chain from primary electron acceptor of PSII to PSI) 4) Photoexcited e- from PSII are transferred to e- transport chain between PSII and PSI -membrane bound e- carriers (e.g cytochrome) pass e- from one carrier to next; each carrier is reduced, gaining energy. 5) This energy is used to pump H+ in thylakoid space -contributes to proton (H+) gradient that drives chemiosmosis (production of ATP via ATP synthase). *In PSI (like PSII), transferred light energy excites P700: Meanwhile in PSII (P700) 6) A photon of light hits a pigment ; boosting e- to a higher level. -Photon energy passed among other pigments molecules until it excites the 2e- in P700 -becomes P700+ (oxidized) + an e- acceptor *P700+ now accepts the e- as they are passed down from PSII* (Each e- falls down e- transport chain from PSII to protein ferredoxin (Fd): 7) Photoexcited e- are passed from PSI e- acceptor to protein Fd. 8)2 e- are transferred from Fd to NADP+ via reductase producing NADPH. -NADP+ has capacity of carrying 2e-: NADP + 2e- + H+ —> NADPH —> NADPH is now available for calvin cycle. ~Light rxn. Summary~ -Photon of light strikes pigment molecule -energy passed from molecule to molecule until it reaches the rxn. center which contains chlorophyll “a” -At rxn. center absorbed light energy drives a redox rxn. -excited e- from rxn. center chlorophyll is captured by primary acceptor -light drives syn. of NADPH and ATP. -by energizing 2 photosystem embedded in thylakoid membrane of chloroplasts -Removal of Hydrogen + e- form H2O by photosystem II (in light) produced O2. -O2 is other major product of light rxn. of photosynthesis. FIG: 10.18: light rxn+ chemiosmosis: the organization of thylakoid membrane. In Summary: the light dependent rxns. use solar power to generate ATP + NADPH, which provide chemical and reducing power respectively to the energy making rxns. of the calvin cycle. An incidental byproduct of light dependent rxn. is O2. *(know this) ATP + NADPH are produced on side facing stroma, where calvin cycle takes place* ~A comparison of chemiosmosis in chloroplasts and mitochondria~ -Chloroplasts and mitochondria generate ATP by chemiosmosis but use diff sources of energy. -mitochondria transfer chemical energy from food to ATP -Chloroplasts transfer from light energy into chemical energy of ATP. -Spatial organization of chemiosmosis differs between chloroplasts and mitochondria but also shows similarities. Fig: 10.17 e- transport chains transform redox energy to a proton motive force -potential energy stored in H+ gradient across membrane. -An e- transport chain pumps H+ to inter-membrane space (M-mitochondria) or thylakoid space(C-chloroplasts). -Drives ATP synthesis as H+ diffuse back into mitochondria matrix(m) or stroma(c) ~10.3~ -Citric acid is catabolic, oxidizing acetyl CoA+ using energy to synthesize ATP. -Calvin cycle is anabolic, building carbs from smaller molecules +consuming energy. -Calvin cycle, like citric acid cycle, regenerates its starting material after molecules enter and leave the cycle. -carbon enters in form of CO2 and leaves as sugar -using ATP as energy source + NADPH as reducing power to add high energy e- to make sugar. ~Calvin Cycle has 3 Phases~ 1)Carbon fixation: carbon enters the cycle as CO2, leaves as sugar named glyceraldehyde 3- phosphate (G3P) 2)Reduction: For net-synthesis of 1 G3P,cycle must place 3x, fixing 3 molecules of CO2. 3)Regeneration of the CO2 acceptor(RuBP): Light rxns. sustain calvin cycle by recycling / regenerating ATP and NADPH. Phase 1: 6C intermediate (unstable), phosphate added after ATP hydrolysis. Phase 2: Reduction to G3P via NADPH -Each G3-P consumes -9 mol ATP -6 mol NADPH -2G3P make 1 glucose. Phase 3: Regeneration of CO2 acceptor (RuBP) -enzyme= rubisco. CH 12:12.1-12.2-the cell cycle
 CHAPTER 13 (13.1-13.3)- Meiosis and Sexual Life Cycles Fig 13.5, 13.6. 


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