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LIFE 102:Chap 7-10
Functions of the membranes
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Separate compartments
control traffic of molecules in and out of compartments
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Membrane Structure
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Lipid bilayer - Hydrophilic and hydrophobic heads.
Fluid mosaic - Proteins suspended in lipid bilayer move easily through membrane to create a constantly changing pattern (fluid, waves).
peripheral, & Integral proteins
Pores
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Why selectively permeable?
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Oxygen in, wastes out
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fluid mosaic model (mosaic)
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the pattern produced by the scattered protein molecules when the membrane is viewed from above because proteins are not stationary Move latterally
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Membrane viscosity is influenced by what factors? What is the role of cholesterol?
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-saturated (thick) and unsaturated (fluid) hydrocarbon tails
-cholesterol reduces membrane fluidity @ moderate temps by reducing phospholipid movement and at low temps. hinders solidification by disrupting the packing of phospholipids
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Cholesteral affects membranes how?
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Buffer. At hot temps it helps reduce fluidity. At cold temps it helps prevent solidification
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Integral membrane proteins
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Inserted in membrane
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Peripheral membrane proteins
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Attached to surface
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How are small, non polar transported across membranes?
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Slip through easily (diffuse)
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What kind of molecules require a transport system?
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Charged/polar or large molecules
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Passive vs active transport
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Passive:diffusion, no energy, hi to lo conc
Active:carrier proteins, energy, can go both ways
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What drives osmosis?
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Water diffuses towards the highest solute concentration to achieve equilibrium
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Plants need hypo, hyper, or iso?
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Hypo
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exocytosis
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substances leave cell
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endocytosis
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cell takes in macromolecules
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Membrane potential
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difference in electrical charge between the inside and outside of a cell
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Electrochemical gradient
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The driving force that causes an ion to move across a membrane, due to the difference in electric charge across the membrane in combination with the difference in the ion's concentration on the two sides of the membrane,
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Active transport (examples)
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Proton pump
sodium/potassium pump
Both create voltage across membrane
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Active transport
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Energy-requiring. Transport protein pumps a molecule/ion across a membrane, often against its conc gradient. Energy comes from ATP
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Cotransport
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transport of one compound is coupled to that of another.
Symport both go in same direction
Antiport go in opposite directions
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Signal sequence
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Address label proteins need in order to be translocated
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Metabolism
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All biochemical reactions that occur in cells
Catabolism
Anabolism
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Catabolism
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Breakdown of larger molecules into smaller ones. Releases energy. Exergonic
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Anabolism
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Buildup of larger molecules out of smaller ones. Cost energy. Endergonic
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First law of thermodynamics
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Law of energy conservation. Energy can be converted but not lost
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Gibbs free energy
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The amount of energy involved in a reaction.
Exergonic
Endergonic
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Reactions with G<0
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Exergonic. Release energy
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Reactions with G>0
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Endergonic. Cost energy
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Molecule thta transfers energy from exergonic to endergonic
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ATP. adenosine tri phosphate. Makes endergonic reactions happen
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ATP components
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An Adenine=N-base
An Ribose
3 phosphate groups
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How is ATP used?
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Can lose a phosphate and release energy ATP->ADP+P
Reverse reaction ADP can bind a phosphate and use same amount of energy
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Activation energy
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Energy required to activate exergonic reactions (lowered by enzymes)
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Mechanism for Activation energy
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Atomic bonds in th emolecules must first be broken. Requires energy
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How to overcome activation energy?
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Heating. Makes atomic bonds easier to break
Enzymes
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How does the enzyme fac the reaction and lower act energy?
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can bind two reactants in the right position for react
enz binding of reactants stresses atom bonds, so they break easily
active site may have prop that facil the reaction due to side groups of amino acids
side groups of amino acids may participate in reaction
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What affects enzyme activity?
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Enzyme/substrate concentration
Temp, pH
Inhibitors/Activators
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More enzymes make the reaction...
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faster
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More substrate makes the reaction...
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faster if there is enough enzyme
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Cofactors
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non-protein molecules required for enzyme activity. Metals, coenzymes(vitamins)
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Inhibitors
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Selectively inhibit enzyme activity
Competitive: Bind at the active site because they are similar to substrate
Non-competitive: Bind at an allosteric site. Changes the shape of the active site so the substrate cannot bind anymore
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Activators
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Selectively activate enzyme activity.
Binding of an activator to an allosteric site stabilizes the enzyme in a cofornmation that allows the substrate to bind.
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Allosteric site
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Where regulator molecules bind (not the active site)
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Course of an enzymatic reaction
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Substrate binds to active site
Enzyme facilitates conversion of substrate to product
product leaves active site and enzyme is ready for next substrate
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Feed-back inhibition
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Product of a reaction inhibits its own production through competitive inhibition.
TLDR: when the product reaches a certain level, the reaction stops
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Allosteric regulation
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allosteric inhibitors and activators
inhibitors do not resemble substrates of enzymes, but bind to enzyme and cause a conformational change
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Cooperativity
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Allosteric - affects other active sites
Substrate binds to active site of multi subunit enzyme and all subunits change shape
Catalytic activity affects sites
Forces it to active form - starts looking for other substrates and binds faster and faster - amplifies enzyme ativity
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Electronegative
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Oxygen. Attracts electrons strongly
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Oxidization
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transfer of electrons from one atom/molecule to another. burned
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Reduced
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Gaines electrons
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Redox reaction
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partial/complete transfer of electrons from one reactant to another
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Oil Rig
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Oxidation is loss
Reduction is gain
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Why doesn't the temperature of metabolically-active cell increase when glucose is catabolized? Where does the energy from glucose metabolism go?
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-Not all the energy from glucose gets metabolized; so not all the energy is released as heat
-Pyruvate and it makes 2ATP
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Respiration (Cellular)
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Glucose combined with Oxygen to produce CO2 and H2O vapor. Catabolic and exergonic. Glucose broken down in little steps
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NAD+
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Oxidezed.. Electron and H+ acceptor.
When it accepts electrons, becomes reduced and becomes NADH which can donate electrons. Shuttle.
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NAD+ or NADH has more energy?
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NADH because it is carrying the extra electrons
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Electron transport chain and where it is located
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Series of proteins located on the inner membrane of the mitochondria
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Oxidative phosphorilation
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Process of ATP synthesis coupled to electron transfer to oxygen via the ETC.90% of ATP produced
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Substrate level phosphorylation
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phosphorylation reaction but does not involve oxygen or ATP. Glycolysis
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What are the 3 main steps linking the breakdown of glucose to the synthesis of ATP?
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1. Glycolysis
2. Krebs (citric acid cycle)
3. Electron Transport Chain
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What does it mean when we div glycolysis into the energy investmentand energy payoffphases?
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2 ATP are invested, 2 ATP are gained (net)
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Glycolysis produces ___ ATP and ___ NADH
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2 and 2
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Where does the citric acid cycle occur?
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mitochondiral matrix
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Where does the electron transport occur within the mitochondrion?
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Inner membrane
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how is the electron transport chain coupled to ATP synthesis?
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-the ETC chain forms a proton gradient that drives ATP synthesis
-as the transmembrane proteins of the ETC are transferring electrons, there are protons being pumped from the matrix to the intermembrane space (impermeability creates proton gradient)
-this gradient is a way to store energy ATP synthase can use to drive ATP synthesis as the protons flow back into the matrix
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What is the role of H+ transport?
Proton-motive force
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protons tend to flow back into the matrix down their electrochemical gradient
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ATP synthase
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Where protons flow through, a channel formed by ATP sythase
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Chemiosmosis
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coupling of electron flow over electron transport chain to ATP production via a proton gradient
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In the citric acid cycle, what is the net yield of ATP?
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2
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In the ETC, what is the net yield of ATP?
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34
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Products of glycolysis?
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Pyruvate, water, energy (ATP and NADH)
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Citric Acid Cycle Products
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2 ATP
6 NADH
2 carbon based products (FADH2)
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Products of ETC
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34 ATP and 6 H20
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How is ATP synthesized by the mitochandria?
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Site of cellular respiration
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What molecules are produced in the citric acid cycle and then used during ETC in the mitochondria?
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NADH and FADH2
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What is fermentation?
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Anaerobic catobolism performed in the absence of oxygen. Bacteria, yeasts, mold
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products of fermentation
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2 ATP and alcohol or lactic acid
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What happens to oxygen molecules during electron transport? What is the final product of electron transport?
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It is an oxidizer so it accepts electrons (usually hydrogen). Water
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Is glucose the only food that can provide energy to form ATP?
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Yes
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How is cellular respiration regulated?
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Feedback inhibition
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Structure of the chloroplast
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... |
What are the light reactions
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Photosystems in the thylakoid membrane transform light energy to chemical energy, stored in NADPH and ATP
USE: light, water, NADP, ADP+P
PRODUCE: NADPH, ATP, oxygen
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How are the light reactions coupled to the calvin cycle?
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Need each other's products.
NADPH and ATP for the Calvin cycle are made by the light reactions
NADP andADP+P for the light reactions are made by the calvin cycle
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Calvin cycle
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CO2 is fixed from the air and reduced to carb (CHO compounds).
USES: CO2
PRODUCES: G3P
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Where are photosynthetic pigments located?
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Hydrophobic molecules in the thylakoid membrane
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Pigments
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molecules that capture photons and get excited
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How does light absorption work?
What happens to the excited electrons in chlorophyll?
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Goes to a primary electron acceptor
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Primary electron acceptor
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Beginning of ETC that delivers electrons to PS1
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Photosystem
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Hundres of pigment molecules with one central chl molecule that recieves all the evergy from the other chl molecules: the reaction center
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Reaction center
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Central chlorophyll molecule that recieves all the energy from the other chl molecules
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How is electron transport coupled to ATP synthesis?
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Through the proton (H+) gradient created during electron transport across membrane. Protons flow DOWN the gradient through the ATPase. Nrg is released as concentrations become more equal, so: ATP synthase powered by proton gradient to ADP + pi--->ATP
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what is carbon dioxide fixation?
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The reaction that combines carbon dioxide with RuBp
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What light reaction products are required for CO2 fixation?
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H and e- provided by NADH and energy by ATP
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How many molecules of CO2 are needed to make one C3 sugar? What else is needed?
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-6
-ATP
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