Lecture Notes for BIO 1
Lecture Notes for BIO 1 01:119:115
Popular in General Biology
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
verified elite notetaker
Popular in Department
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.
Reviews for Lecture Notes for BIO 1
Report this Material
What is Karma?
Karma is the currency of StudySoup.
You can buy or earn more Karma at anytime and redeem it for class notes, study guides, flashcards, and more!
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.
Are you sure you want to buy this material for
You're already Subscribed!
Looks like you've already subscribed to StudySoup, you won't need to purchase another subscription to get this material. To access this material simply click 'View Full Document'