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6 Key Chapter Terms central vacuole centriole centrosome chromatin chromosome cilium contractile vacuole crista electron microscope (EM) endoplasmic reticulum (ER) extracellular matrix (ECM) flagellum food vacuole gap junction granum intermediate filament light microscope (LM) lysosome microfilament microtubule mitochondrial matrix nucleoid nucleolus nucleus phagocytosis plasmodesma pseudopodium scanning electron microscope (SEM) stroma thylakoid tight junction transmission electron microscope (TEM) Concepts How We Study Cells 1. Know the brief history of cell study, the cell theory, and the scientists. 6 2. Know the different functions of the light microscope, transmission electron microscope, and scanning electron microscope.pg96 Light Microscope(LMs): Refracts(bends) the visible light passing through a specimen such that a projected image is magnified. Transmission electron microscope: (TEM) A beam of electrons is passed through a thin section of a specimen stained with atoms of heavy metals , and electromagnets, acting as lenses, focus the image onto a screen or film. Electron Microscope(EM) : Focuses a beam of electrons through the specimen. The short wavelength of the electron beam allows a resolution of about 2 nanometers ( a hundred times greater than that of the light microscope. Scanning Electron Microscope(SEM): an electron beam scans the surface of a specimen usually coated with a thin gold film, exciting electrons from the specimen, which are detected and translated into an image on a video screen. ( image appears 3-D)> The Nucleus and Ribosomes 3. Know the structure and function of the nucleus, including the role of the pore complex.pg102 The nucleus contains most of the genes in the eukaryotic cell. (might want to look up nuclear envelope, nucleolus, chromatin,and nuclear lamina.) Pore Complex: An intricate protein structure that lines each pore and regulates the entry and exit of certain macromolecules and particles. ( Refer to page 103 Figure 6.10) 4. Know the structure and function of ribosomes. Distinguish between free and bound ribosomes in terms of location and function. Pg 102 Ribosomes , particles made of ribosomal RNA and protein, are the organelles that carry out protein synthesis. (structure: non membranous organlle free in cytoplasm or bound to rough ER or nuclear envelope.) Free Bound: Suspended in the cytosol. Most of the proteins made on free ribosomes function within the cytosol ( i.e. : enzymes that catalyze the first steps of sugar breakdown.) Bound: Attached to the outside of the endoplasmic reticulum or nuclear envelope. (generally make proteins that are destined either for insertion into membranes, for packaging within certain organelles such as lysosomes or for export from the cell (secretion) (i.e. : cells of the pancreas have high proportion of them.) The Endomembrane System 5. Compare the structure and functions of smooth and rough ER.pg 104/105 Smooth ER: Lack ribosomes. Important to synthesis of lipids(fats) , including oils, phospholipds, and steroids. Its enzymes are involved in phospohlipid, steroid, and sex hormone synthesis; carbohydrate metabolism, and detoxification of drugs and poisons. (Also functions in storage and relase of calcium ions during muscle contraction.) Rough ER: Makes secretory proteins, manufactures membranes for the cell. Proteins intended for secretion are manufactured by membrane bound ribosomes and then threaded into the lumen of the rough ER, where they fold into their native conformation. 6. Know how secretory proteins are produced in the endomembrane system through sequential steps. Pg 105 Proteins intended for sectretion are manufactured by membrane bound ribsomes and then threaded into the lumen by the rough ER, where they fold into their native conformation. Many are covalently bonded to small carbohydrates to form glycoproteins. Secretory proteins are transported from the rough ER in membrane bound transport vessicles. 7. The intracellular digestion function of lysosomes. Pg107 In some protists, lysosomes fuse with food vacoules to digest material ingested by phagocytosis.) Figure 6.14 pg 107 Lysosomes also recycle a cell's own macromolecules by engulfing damaged organelles or small bits of cytosol, a process known as autophagy. 8. Know different kinds of vacuoles and their function. Food Vacoule: A vacuole in which phagocytized food is digested. Contractile Vacoules: pumps excess water out of freshwater protists, thereby maintaining the appropriate concentration of salts and other molecules. Central Vacoule: stores orgainic compounds and inorganic ions for the cell. Poisonous or unpalatable compounds, which may protect the plant from predators, and dagerous metabolic by-products may also be contained in the vacoule. Other Membranous Organelles 9. Know the structure and function of a mitochondrion.pg 108 Sites of cellular respiration, the metabolic process that generates ATP by extracting energy from sugars, fats, and other fuels with the help of oxygen.(refer to page 110 Figure 6.17 for detailed structure) 10. Know the structure and function of a chloroplast. Pg 109 Site of photosynthesis . Found only in plants and algae. They convert solar energy to chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from CO2 to H20. Contain the green pigment chlorophyll, along with the enzymes and the other molecules that function in the photosynthetic producution of sugar. ( See Figure 6.18 page 111 for specific structure) The Cytoskeleton 11. Know the functions of the cytoskeleton. A network of fibers( microtubles, microfilaments, and intermediate filaments.) that give mechanical support, function of cell motility, and transmit mechanical signals from the cell's surface to its interior. Interacts with special proteins called motor proteins to produce cellular movements. 12. Know how the function of cilia and flagella relates to their functions. They are both locomoter extensions of some eukary cells. Cilia are numerous and short. Flagella occour one or two to a cell and are longer. Cilia or flagella attached to stationary cells of a tissue move fluid past the cell. A flagellum has an undulating motoin that generates forice in the same direction as the flagellum's axis. Cilia work more like oars, with alternating power and recovery strokes generating force in a direction perpendicular to the ciliums axis. ( see figure 6.23 page 115) Cell Surfaces and Junctions 13. Know the basic structure, composition, and function of cell wall. Plant cell walls are composed of microfibrils of cellulose embedded in a matrix of polysaccharides and proteins. The primary cell wall secreted by a young plant cell is relatively thin and flexible. Adjacent cells are glued together by the middle lamella, a thin layer of polysaccharides ( called pectins.) When they stop growing, some cells secrete a thicker and stronger secondary cell wall between the plasma membrane and the primary cell wall. 14. Name the intercellular junctions found in plant and animal cells and the functions. Plasmodesmata are channels in plant cell walls through which the plasma membranes of boarding cells connect, thus linking most cells of a plant into a living continuum. (Water, small solutes, and even some proteins and RNA molecules can move through these channels.) 3 main types in animals At tight junctions, proteins hold adjacent cell membranes tightly together , creating an impermeable seal across a layer of epithelial cells. Desmosomes : Reinforced by intermediate filaments, are anchoring junctions between adjacent cells. Gap Junctions (communicating junctions) : Cytoplasmic connections that allow for the exchange of ions and small molecules between cells through protein surrounded pores. Chapter 7 Terms: active transport aquaporin diffusion endocytosis exocytosis facilitated diffusion flaccid fluid mosaic model hypertonic hypotonic integral protein isotonic osmosis passive transport peripheral protein phagocytosis pinocytosis plasmolysis receptor-mediated endocytosis selective permeability turgid 1. 2. 3. 4. 5. 6. 7. 8. Concepts Membrane Structure Phospholipids are amphipathic molecules. Know the components of cell membrane. Phospholipid is an amphipathic molecule because it has both a hydrophilic region and a hydrophobic region. Fluid Mosaic Model the membrane is a fluid structure with a mosaic of various proteins embedded in or attached to a double layer (bilayer) of phospholipids. Understand the fluidity of the components of a cell membrane and how membrane fluidity is influenced by temperature and membrane composition. Membranes must be fluid to work properly. When a membrane solidifies, its permeability changes, and enzymatic proteins in the membrane may become inactive. A membrane remains fluid as temperature decreases, until finally the phospholipids settle in a closely packed arrangement and the membrane solidifies. The temperature at which a membrane solidifies depends on the types of lipids its made of. The membrane remains fluid to a lower temperature if it is rich in phospholipids with unsaturated hydrocarbon tails. Traffic Across Membranes Distinguish between peripheral and integral membrane proteins. Peripheral proteins are not embedded in the lipid bilayer at all; they are appendages loosely bound to th surface of the membrane, often to the exposed parts of integral proteins. Integral Proteins penetrate the hydrophobic core of the lipid bilayer. Hydrophobic regions are composedof noncovalent amino acids; coiled into helix. Know major functions of membrane proteins. Different molecules cross cell membrane through differernt way depending on their size, polarity and charge. Polarity non-polar Charge non-charged Size small molecules Know how hydrophobic molecules cross cell membranes. Hydrophobic (nonpolar) molecules can cross the membrane with ease. Hydrophilic molecules and ions are transported by transport proteins. Diffusion is a spontaneous process. Molecules moving from and area of high concentration to low concentration. The diffusion will continue until equilibrium is reached. Distinguish among hypertonic, hypotonic, and isotonic solutions. Hypertonic higher concentration of solutes outside the cell. Hypotonic higher concentration of solutes inside the cell. Isotonic equal concentration of solutes. 9. Define osmosis and predict the direction of water movement based on differences in solute concentrations. The diffusion of water across a selectively permeable membrane. Water diffuses across the membrane from the region of lower concentration to the region of higher concentration. 10. Explain how transport proteins facilitate diffusion. Two types of transport proteins are channel and carrier proteins. Channel proteins simply provide corridors that allow a specific molecule or ion to cross the membrane. Carrier proteins seem to undergo a subtle change in shape that somehow translocates the solute-binding site across the membrane. 11. Distinguish among osmosis, facilitated diffusion, and active transport. Osmosis - The diffusion of water across a selectively permeable membrane. Water diffuses across the membrane from the region of lower concentration to the region of higher concentration. Facilitated Diffusion Proteins allow certain molecules and ions to cross the membrane by creating a corridor. Active Transport Uses energy to move solutes against their concentraton gradients. 12. Explain how large molecules are transported across a cell membrane. Large molecules cross the cell membrane by a mechanism involving vesicles. Endocytosis the cell takes in macromolecules and particulate matter by forming new vesicles from the plasma membrane. Phagocytosis eating of the cell extends pseudopodia to surround food particle. The particle is digested after the vacuole fuses with a lysosome containing hydrolytic enzymes. Exocytosis the cell secretes macromolecules by the fusion of vesicles with the plasma membrane. Materials are expelled from the cell. 13. Distinguish between pinocytosis and receptor-mediated endocytosis. Pinocytosis drinking of the cell (forms pocket) the cell gulps droplets of extracellular fluid into tiny vesicles. Its not the fluid itself that its needed, but the molecules dissolved in the droplet. Receptor-mediated endocytosis forms pocket same as pinocytosis but the vesicle has coated pits that act as receptors to recognize certain molecules (specific). Chapter 8 Terms: activation energy active site allosteric regulation anabolic pathway catabolic pathway cofactor competitive inhibitor endergonic reaction energy energy coupling entropy enzyme exergonic reaction feedback inhibition first law of thermodynamics free energy kinetic energy metabolic pathway- begins with a specific molecule, which is then altered in a series of defined steps, resulting in a certain product. metabolism- emergent property of life that arises from interactions between moecules within the orderly environment of the cell. noncompetitive inhibitor potential energy second law of thermodynamics thermodynamics Concepts: Metabolism, Energy, and Life 1. The role of catabolic and anabolic pathways in cellular metabolism. Catabolic (breakdown)- cellular respiration- the sugar glucose and other organic fuels are broken down in the presence of oxygen and carbon dioxide and water. Energy that was stored in the organic molecules now becomes available to do the work of the cell. Anabolic (build up) biosynthetic pathway- consume energy to build up complicated molecules from simpler ones. 2. Distinguish between kinetic and potential energy. Kinetic energy associated with the relative motion of objects. Heat or thermal energy is associated with the random movement of atoms and molecules. Potential Energy that matter possesses because of its location or structure. Molecules store energy because of the arrangement of their atoms. 3. Explain why an organism is considered an open system. Because energy can be transferred between the system and the surroundings. Organisms absorb energy and release heat and metabolic waste products to surroundings. 4. Explain the first and second laws of thermodynamics. First Law- (principle of conservation of energy) Energy can be transferred and transformed, but it cannot be created or destroyed. Second Law- Every energy transfer or transformation increases the entropy (measure of disorder) of the universe. For a process to occur spontaneously, it must increase the entropy of the universe. 5. Define each component of the equation for free-energy change, and know the way they change in spontaneous and nonspontaneous reactions. G = H TS; H symbolizes the change in the systems enthalpy (total energy). S is the change in the systems entropy, and T is the absolute temperature in Kelvin units. With the value of G we can predict whether the process will be spontaneous. Spontaneous- a process that can occur without an input of energy. Nonspontaneous- a process that cannot occur without an input of energy. G must have a negative value for the process to be spontaneous. 6. Distinguish between exergonic and endergonic reactions. Exergonic reaction in which there's a net release of free energy. Loses free energy (G), G is negative. Spontaneous. Endergonic reaction that absorbs free energy from its surroundings. Stores free energy in molecules (G increases, G is positive) Nonspontaneous. 7. Know the structure of ATP and explain how ATP supports cellular work. Structure: ATP (Adenosine triphosphate) contains the sugar ribose, with the nitrogenous base adenine and a chain of three phosphate groups bonded to it. Cellular work: mechanical, transport, and chemical. The bonds between the phosphate groups ATP's of tail can be broken by hydrolysis. When the terminal phosphate bond is broken, a molecule of inorganic phosphate leaves the ATP, which becomes adenosine diphosphate, or ADP. The reaction is exergonic and under standard conditions releases energy. A phosphate group is transferred from ATP to some other molecule and this phosphorylated (recipient of the phosphate group) molecule undergoes a change that performs work. Enzymes Are Catalytic Proteins 8. The function of enzymes in biological systems. A catalyst is a chemical agent that speeds up a reaction without being consumed by the reaction; enzymes are catalytic proteins. Activation energy is the amount of energy needed to push the reactants over an energy barrier so that the "downhill" part of a reaction can begin. An enzyme catalyzes a reaction by lowering the EA barrier, enabling the reactant molecules to absorb enough energy to reach the transition state even at a moderate temperature. 9. The mechanisms by which enzymes lower activation energy. First, in reactions involving two or more reactants, the active site provides a template for the substrates to come together in the proper orientation for a reaction to occur between them. Second, as the active site of an enzyme clutches the bound substrates, the enzyme may stretch the substrate molecules toward their transition-state conformation, stressing and bending critical chemical bonds that must be broken during the reaction. Third, the active site may also provide a microenvironment that is more conductive to a particular type of reaction than the solution itself would be without the enzyme. Fourth, the direct participation of the active site in the chemical reaction. Subsequent steps of the reaction restore the side chains to their original states, so the active site is the same after the reaction as it was before. 10. Explain how substrate concentration, temperature, pH, cofactors, and enzyme inhibitors affect the rate of an enzyme-catalyzed reaction. Substrate concentration the more substrate molecules are available, the more frequently they access the active sites of the enzyme molecules. At some point, the concentration of substrate will be high enough that all enzyme molecules have their active sites engaged. Temperature Up to a point, the rate of an enzymatic reaction increases with increasing temperature partly because substrates collide with active sites more frequently when the molecules move rapidly. pH values for most enzymes fall under the range of pH 6-8 but there are some exceptions. Cofactors Many enzymes require nonprotein helpers for catalytic activity. Enzyme Inhibitors competitive inhibitors: reduce the productivity of enzymes by blocking substrates from entering active sites. Noncompetitive inhibitors: they impede enzymatic reactions by binding to another part of the enzyme. This interaction causes the enzyme to change shape, rendering the active site less effective at catalyzing the conversion of substrates into products. The Control of Metabolism 11. Explain how metabolic pathways are regulated. Allosteric regulation- protein's function at one site is affected by the binding of a regulatory molecule to a separate site. It may result in either inhibition or stimulation of an enzyme's activity. Chapter 9 Terms: aerobic anaerobic cellular respiration chemiosmosis citric acid cycle facultative anaerobe fermentation glycolysis oxidation oxidative phosphorylation redox reaction reducing agent reduction substrate-level phosphorylation Concepts: The Principles of Energy Harvest 1. Distinguish between fermentation and cellular respiration. Fermentation: is a partial degradation of sugars that occurs w/out the use of oxygen. Celluar Respiration: In which oxygen is consumed as a reactant along with the organic fuel.( another defintion: uses oxygen in the breakdown of glucose to yield carbon dioxide and water and the release energy as ATP and heat.) This exergonic process has a free energy change of -686 kcal/mol of glucose. 2. Write the summary equation for cellular respiration. C6H1206+602 6CO2+6H20+energy ( ATP+ heat) 3. Define oxidation and reduction. Oxidation: the loss of electrons from one substance: Reduction: the addition of electrons to another substance. 4. Describe the role of NAD+ in cellular respiration. NAD+ functions as an oxidizing agent during respiration, it is an electron acceptor.(co enzyme) ots reduced form is NADH. 5. Explain the role of the electron transport chain and the role of oxygen in cellular respiration. Know the sequence of electron flow in cellular respiration. The electron transport chain breaks the "fall" of electrons in reactions into a series of smaller steps and stores some of the released energy in a form that can be used to make ATP. The transport chain consits of a number of molecules, mostly proteins, built in the inner membrane of a mitochondrion. Electrons removed from the food are shuttled by NADH to the "top, higher energy end of the chain. At the bottom, " lower energy end, oxgen captures these electrons along with the hydrogen nulei(h+) forming water. ( see page 164 for full answer) The Process of Cellular Respiration 6. Name the three stages of cellular respiration and state the region of the eukaryotic cell where each stage occurs. Glycolysis: occurs in the cytosol Citric acid cycle ( krebs cycle): located in the mitochondrial matrix. Oxidative Phosphorylation: located in the inner membrane of the mitchondria. 7. Describe where pyruvate is oxidized to acetyl CoA, what molecules are produced, and how this process links glycolysis to the citric acid cycle. The pyruvate is actively transported into the mitochondriion. Before the citric acid cycle begins, a series of steps occurs within a multienzyme complex. A carboxyl group is removed from the three carbon pyruvate and realsed as CO2; the remaining two carbon group is oxidized fo form acetate with the accompanying reduction of NAD+ to NADHl and the coenzyme A is attached to the aceate by an unstable bond, forming acetyl CoA. (see page 168 paragraph 2 for full explanation) Glycolysis harvests chemical energy by oxidizing glucose to pyruvate. Pyruvate is oxidized to form acetyl CoA. 8. List the products of the citric acid cycle. Explain why it is called a cycle. In the cycle, the acetyl group of acetyl CoA is added t oxaloacetate to form citrate, which is progessively decomposed back to oxaloacetate. For each turn of the citric acid cycle, two carbons enter in the reduced form from acetyl CoA; two carbons exit completely oxidized as Co2; three NADH and one FADH2 are formed, one ATP is made by substrate level phosphorylation. There are two turns of the citric acid cycle for each glucose molecule oxidized. 9. Distinguish between substrate-level phosphorylation and oxidative phosphorylation. Substrate: The formation of ATP by directly transferring a phosphate group to ADP from an intermediate substrate in catabolism. ( see figure 9.7 pg 165 for reference) Oxidative: The production of ATP using energy derived from the redox reactions of an electron transport chain. 10. Explain how the exergonic "slide" of electrons down the electron transport chain is coupled to the endergonic production of ATP by chemiosmosis. 11. Explain where and how the respiratory electron transport chain creates a proton gradient. The electron transport chain creates the protin gradient. When some members of the chain pass electrons, they also accept and release protons, which are pumped into the intermembrane space at three points. The resulting proton gradient stores potential energy, referred to as the protonmotive force. 11. Describe the structure and function of the four subunits of ATP synthase. A rotor in the inner mitochondrial membrane, a knob that protrudes into the mitchondrial matrix, an internal rod extending from from the rotor into the knob, and a stator, anchored next to the rator, that holds the knob stationary. Rotor: spins when H+ flows past it down the H+ gradient. Stator: holds the knob stationary Rod: activates catalytic sites in the knob Three catalytic sites in the statoinary knob join inorganic phosphate to ADP to make ATP. 12. Summarize the net ATP yield from the oxidation of a glucose molecule by constructing an ATP ledger. ( page 173, figure 9.16) ( Or you can look under the subtitle in blue : An accounting of ATP production by cell. Respiration, page 173, paragraph 2 through page 174) Related Metabolic Processes 13. The basic function and products of fermentation. Fermentation enables some cells to produce ATP without the use of oxygen. Alcohol fermentation: Pyruvate is converted into acetaldehyde, and CO2 is released. Acetaldehye is then reduced by NADH to form ethanol and NAD+ is regenerated. Lactic acid fermentation: pyruvate is reduced directly by NADH to form lacate acid and recyle NAD+. ( Muscle cells make ATP by lactic acid fermentation when energy is in high demand and oxygen supply is low) 15. Compare the processes of fermentation and cellular respiration. Both fermentation and respiration use glycolysis with NAD+ as the oxidizing agent to convert glucose and other organic fuels to pyruvate. To oxidize NADH back to NAD+, fermentation uses pyruvate or acetaldehyde as the final electron acceptor, whereas respiration uses oxygen, via (through) the electron transport chain. Chapter 10 Terms: autotroph Calvin cycle cyclic electron flow heterotroph light reactions noncyclic electron flow photophosphorylation photosynthesis photosystem photosystem I (PS I) photosystem II (PS II) rubisco stoma- microscopic pores through which CO2 is absorbed and oxygen is released. stroma- dense fluid within the chloroplast Concepts: The Process That Feeds the Biosphere 1. Distinguish between autotrophic and heterotrophic nutrition. Autotrophic: "self-feeders" (producers) they sustain themselves without eating anything derived from other organisms. They produce their organic molecules from CO2 and other inorganic raw material obtained from the environment. Heterotrophic: (consumers) - They live on compounds produced by other organisms. 2. Distinguish between photoautotrophs and chemoautotrophs. Photoautotrophs: Organisms that use light as a source of energy to synthesize organic substances. (plants) Chemoautotophs: Instead of using light for energy, they oxidize inorganic substances. Unique to certain prokaryotes. 3. Describe the structure of a chloroplast, listing all membranes and compartments. Chlorophyll green pigment located within chloroplasts. The light absorbed by chlorophyll is what drives the synthesis of organic molecules in the chloroplast. Resides in the thylakoid membranes. Mesophyll the tissue in the interior of the leaf. Stomata CO2 enter the leaf, and oxygen exits by these microscopic pores. Stroma dense fluid within the chloroplast. Thylakoids membranous sacs that segragate the stroma from another compartment. Grana stacked thylakoids. The Pathways of Photosynthesis 14. Write a summary equation for photosynthesis, compare phtosynthesis and respiration. 6CO2 + 12H2O + light energy -> C6H12O6 + 6O2 + 6H2O -Simplyfied indicating net consuption of water6CO2 + 6H2O + light energy -> C6H12O6 + 6O2 The overall chemical change during photosynthesis is the reverse of the one that occurs during cellular respiration. Both processes occur in plants. 15. Explain the role of redox reactions in photosynthesis know where is oxygen produced from. Plants split water as a source of electrons from hydrogen atoms, releasing oxygen as a byproduct. Extraction of hydrogen from water and incorporating it into sugar; waste product of photosynthesis is oxygen which is released into the atmosphere. 16. Describe the two main stages of photosynthesis in general terms. Light Reactions: (the photo part)Solar energy is captured and transformed into chemical energy. Calvin Cycle: (the synthesis part)Chemical energy is used to make organic molecules of food. 17. The visable light that are most effective for photosynthesis. Visible light violet-blue and red light 18. Explain what happens when a solution of chlorophyll a absorbs photons. Explain what happens when chlorophyll a in an intact chloroplast absorbs photons. 19. List the components of photosystem I and II and explain the function of each component. Photosystem I: the reaction center chlorophyll is known as P700 because it most effectively absrobs light of wavelength 700nm (in the far red part of the spectrum). Photosystem II: the reaction center chlorophyll a is known as P680 because this pigment is best at absorbing light having a wavelength og 680nm (red part of the spectrum). 20. Trace the movement of electrons in noncyclic electron flow. Trace the movement of electrons in cyclic electron flow. Noncyclic electron flow: Pushes electrons from water, there they are at a low state of potential energy, to NADPH, there they are stored at a high state of potential energy. Cyclic electon flow: electrons cycle back from ferrodoxin (Fd) to the cytochrome complex and from there continue on to a P700 chlorophyll in the PSI reaction center. 21. The functions of cyclic and noncyclic electron flow. Cyclic: Uses photsystem I but not photosystem II. Short circuit. Electrons cycle back from ferrodoxin (Fd) to the cytochrome complex and from there continue on to a P700 chlorophyll in the PSI reaction center. There is NO production of NADPH and NO release of oxygen. Generates ATP. Noncyclic: Transfer of electrons from water to ferredoxin via the two light reactions and intermediate carriers. Produces ATP and NADPH I roughly equal quantities. Pushes electrons from water, there they are at a low state of potential energy, to NADPH, there they are stored at a high state of potential energy. 12. Compare chemiosmosis between oxidative phosphorylation in mitochondria and photophosphorylation in chloroplasts. Oxidative Phosphorylation in mitochondria -High energy electrons are extracted from organic molecules. -Mitochondria transfer chemical energy from food molecules to ATP. -The inner memebrane of the mitochondrion pumps protons from the mitochondrial matrix out to the intermembrane space, which then serves as a reservoir of hydrogen ions that powers the ATP synthase. Photophosphorylation in chloroplasts -Chloroplasts capture light energy and use it to drive electrons to the top of the transport chain. -Chloroplats transform light energy into chemical energy in ATP. -The thylakoid membrane of the chloroplast pumps protons from the stroma into the thylakoid space, which functions as the H+ reservoir. 13. The function of each of the three phases of the Calvin cycle. Phase 1. Carbon Fixation: Attaches CO2 molecules to a five-carbon sugar named ribulose bisphosphate. Rubisco is the enzyme that catalyzes this step. The product is a six-carbon intermediate so unstable that it immediately splits in half, forming two molecules of 3-phosphoglycerate(for each CO2). Phase 2. Reduction: Each molecule of 3-phosphoglycerate receives an additional phosphate group from ATP, becoming 1, 3-biphosphoglycerate. A pair of electrons from NADPH reduces 1, 3-biphosphoglycerate to G3P. Phase 3. Regeneration of the CO2 acceptor (RuBP): The carbon skeletons of five molecules of G3P are rearranged by the last steps into three molecules of RuBP. The RuBP is now prepared to receive CO2 again. The light reactions regenerate the ATP and NADPH. 14. The role of ATP and NADPH in the Calvin cycle. ATP and NADPH provide the energy and electrons to reduce carbon dioxide (CO 2) to organic molecules. ATP and NADPH convert 3-PGA to G3P. ATP: The removal of electrons from water molecules and their transfer to NADP+ requires energy. Regenerates 3 RuBP. ... View Full Document

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