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92 Cards in this Set
- Front
- Back
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photosynthesis (PHTS)
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- one of the oldest metabolic pathways on earth
- use of sunlight to make simple sugars - 6H2O + 6CO2 + LIGHT ENERGY --> C6H1206 +602 |
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Lights Reactions (PHTS)
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- light is captured
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Calvin Cycle (PHTS)
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- chemical energy is used to make organic molecules
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Autotrophs
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- "self feeders" Greek
- make their own foods with out consuming organic molecules derived from other organisms |
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Producers
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- produce food supply for their relative system
(plants are producers of our biosphere) |
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What two categories do plants fall under?
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- autotrophs and producers
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What term combines the concept of "self feeding" from the term autotrophs and the use of light light to engage this process?
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- Photoautotroph
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Photoautotroph
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- organisms that produce organic molecules from inorganic molecules using the energy of light
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All green plants have...
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chloroplasts in the cells and carry out photosynthesis.
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Chlorophyll
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- a light absorbing pigment in the chloroplasts
- central to photosynthesis |
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Sidenotes: The Leaf
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- leaf is an above-ground plant organ specialized for the process of photosynthesis.
- Leaves are typically flat (laminar) and thin, which evolved as a means to maximise the surface area directly exposed to light. - the internal organisation of leaves has evolved to maximise exposure of the photosynthetic organelles, the chloroplasts, to light and to increase the absorption of carbon dioxide, in a process called photosynthesis. |
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Mesophyll
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- green tissue in the interior of the leaf
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What is concentrated in the mesophyll?
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- chloroplasts
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Chlorophyll
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- a light absorbing pigment in the choloroplast
- responsible for the green color |
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Stromata
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- tiny pores in which CO2 enters and O2 exits
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Parts of Chloroplast
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- Outer Membrane
- Intermembrane Space - Inner Membrane - Stroma (thick fluid) - Granum (concentrated thylakoid stack) - Thyakloid (interconnected membrane sacs) - Thyakloid Space (analogous to inter membrane space of mitohondrion) |
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Stroma
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- thick fluid fills chloroplast
- make sugar |
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Thylakoids
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- membranes have chlorophyll built into them
- suspended in stroma - stacked in grana |
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O2 yielded from photosynthesis comes from which reactant?
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- H20
- CO2 and H from water make the sugar |
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What is happening during photosynthesis?
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- Redox reaction
- H20 is oxidized (loses electrons and protons) - CO2 is reduced (gains electrons and protons) - endergonic reaction "going up energy hill" - electrons gain energy by light energy captured by chloroplasts - light energy --> chemical energy (stored in bonds of sugar molecules) |
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what is happening during cellular respiration?
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- glucose oxidized
- O2 reduced |
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How do plants generate O^2?
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by splitting H2O
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During photosynthesis the reactants CO2 and H2O end up in what products?
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- CO2 make glucose and water
- H2O ends up in glucose, water and Oxygen - No CO2 becomes oxygen |
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During photosynthesis H2O molecules....
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- lose electrons (oxidized) and H+
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During photosynthesis CO2 is...
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- gains electrons (gain electrons)
- electrons and H+ are added to it |
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Food producing redox reactions that occur in photosynthesis are ___hill energy reactions
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- up
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As water is oxidized CO2 is
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- reduced
- electrons gain energy |
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light energy becomes
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- chemical energy and stores in chemical bonds of sugar molecules
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Light Reaction
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- steps that convert light energy to chemical energy and produce O2
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Where do light reactions occur
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- thylakoid membranes
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What happens during the light reaction?
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- water is split (source of electrons + O2 waste product)
- light energy ( absorbed by chlorophyll molecules drive the transfer of electrons and H+ == NADP+ --> NADPH) - absorb solar energy and convert it to chemical energy stored in ATP and NADPH - NO sugar |
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What is the purpose of NADPH?
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- temporarily stores electrons and provides "reducing power" to the Calvin Cycle
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The two stages of photosynthesis...
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Light reactions and Calvin Cycle
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Calvin Cycle
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- cyclic series of reactions that assembles sugar molecules using CO2 and the energy containing products of the light reactions
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Carbon Fixation
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- the incorporation of carbon from CO2 into organic compounds
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What happens to the NADPH produced during the light reaction in the Calvin Cycle?
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- provides the electrons for reducing carbon in the Calvin Cycle
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Light Reactions produce
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- NADPH and ATP (stored solar energy)
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does the Calvin Cycle require direct sunlight?
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no
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If the Calvin Cycle does not require sunlight then why does it run during the daytime?
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- because it uses the ATP and NADPH generated by light reactions to power its cycle
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Sugar construction occurs in the ....
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- Calvin Cycle
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Visible Light Wavelength
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- 380 - 750 nm
- violet/ blue/ green/ yellow/ orange/ red |
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Shorter the wavelength
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- the more the energy
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Pigments in the thylakoid membrane
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- absorb or transmit/reflect wavelengths
- what we we see is the wavelength reflected |
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Chlorophyll a (wavelength absorption/reflection)
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- pigment in thylakoid membrane
- absorbs mainly blue-violet and red light - reflects green/ looks green |
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Chlorophyll b (wavelength absorption/reflection)
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- pigment in thylakoid membrane
- absorbs blue and orange light - reflects yellow - green - broadens the range of light that a plant can use by CONVEYING absorbed ENERGY to CHLOROPHYLL A which then puts the energy to work the light reactions |
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Carotenoids
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- pigment in thylakoid membrane
- appear as shades of yellow and orange - Broadens spectrum of colors that can drive photosynth. by passing energy to CHLOROPHYLL A - Photoprotection absorb and dissipate excessive light energy what would damage cholorophyll or interact with O2 to form oxidative molecules |
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How does the representation of electromagnetic energy understand as parcel of light (photon) relate to the photosynt
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- Each pigment absorbs a certain wavelength of light because it is able to absorb the specific amounts of energy in those photons
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When a pigment absorbs a photon ...
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- one of the pigments electrons jump energy levels
- ground --> excited state - farther from the nucleus = more potential energy |
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In its native habitat of the thylakoid membrane, chlorophyll passes off its _______ _______ to a neighboring molecule before it has a chance to drop back to the ground state
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- excited electron
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Where do you find photosystems?
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- thylakoid membranes
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What are photosystems composed of?
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- consists of a number of light harvesting complexes surrounding a reaction center complex
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Pigment molecule bound to proteins
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photosystems
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3 pigment molecules
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- chlorophyll a (blue/red)
- chlorophyll b (blue/ orange) - carotenoid (broad) |
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Reaction Center Complex
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- receives solar energy from light harvesting complexes
- contains a pair of chlorophyll a molecules and a a molecule called the primary electron acceptor |
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Primary Electron Acceptor
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- capable of accepting electrons and becoming reduced
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Brief Description of the First Phase of the Light Reaction
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- solar powered electron transfer in which photons are absorbed by photosystems by light harvesting attena --> exciting electrons --> electrons pass energy molecule to molecule --> reaches reaction center in which a primary electron acceptor molecule is reduced
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Which photosystem functions first in the light reaction?
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- Photosystem II
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photosystem II --> rxn center P680 (chlorophyll a)
photosystem I --> rxn center _______ |
- P700
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In the light reaction, light energy is transformed into ...
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- chemical energy
- ATP and NADPH |
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Briefly describe the movement of electron from H2O during the light reaction.
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- electrons removed from water molecules --> photosystem II --> photosystem II --> NADP+
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Between the two photosystems, the electrons move down an _______ ______ _______ and provide energy for the synthesis of ___.
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- electron transport chain; ATP
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Light Reaction Step 1
A pigment molecule in a light harvesting complex (photosystem) absorbs a ______ of light. The energy is passed to the other pigment molecules and finally to the ________ center of the photosystem, where it excites an electron of chlorophyll P___ to a higher state. |
- photon
- reaction - 680 |
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Light Reaction Step 2
The electron of chlorophyll P680 that gets excited to a higher energy state is captured by the _______ ______ ________. |
- primary electron acceptor
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Light Reaction Step 3
Water is ______, and its electrons are supplied one by one to P680, each replacing an electron lost to the ______ _____ _____. The oxygen atom combines with an oxygen from another split water molecule to form a molecule of 02. |
- split
- primary electron acceptor |
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When is 02 formed?
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- after water is split to replace electrons in the P680 RXN center lost to the Primary Electron Accpetor O combines with another O from a split water and makes O2
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In depth view of the excitation process of chlorophyll a and chlorophyll b.
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- the energy of the photon is converted to the potential energy of an electron raised from its ground state to an excited
- In chlorophyll a and b, it is an electron from the magnesium in the porphyrin ring that is excited |
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Parts of Chlorophyll
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A chlorophyll molecule has a hydrophobic "tail" that embeds the molecule into the thylakoid membrane. The "head" of a chlorophyll molecule is a ring called a porphyrin.
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Porphyrin Ring
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The porphyrin ring of chlorophyll, which has a magnesium atom at its center, is the part of a chlorophyll molecule that absorbs light energy.
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Light Reaction Step 4
Each photoexcited electron passes from ____________ __ to _________ __ via an ________ _______ ______. The exergonic fall of electron provides energy for the synthesis of ATP by pumping ___ __ across the membrane. |
- Photosystem II to Photosystem I via an electron transport chain
- H+ |
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Light Reaction Step 5
Simultaneous to the excitation of P680/P.sys 2, Light energy excites an electron of chlorophyll _____ in the ____ center of photosystem _. The primary electron electron acceptor captures the electron, and an electron from the bottom of the ETC replaces the lost electron in ____. |
- P700
- reaction - I - P700 |
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Light Reaction Step 6
The excited electron of photosystem I is passed through a short ETC to _____ reducing it to ____. |
- NADP+ ; NADPH
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What purpose does the ETC serve during the light reaction?
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- creates gradient for chemiosmosis (H+ in stroma moves in the thylakoid space)
- flow of electrons from photosystem II to photosystem I - electron P680 replacement by splitting water in - delivery of electron from H20 --> P680 --> P700 --> NADP+ (creating)==> NADPH |
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HOw to make a gradient...
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- ETC chain uses the energy released as it passes electrons down the chain pump hydrogen ions across the membrane
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Where are the two photosystems and the ETC that connects them located?
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- within the thylakoid membrane of the chloroplast
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Photoexcited electrons are passed down the ETC connecting the two photosystems, hydrogen ions are .....
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- pumped across the membrane from the stroma into the thylakoid space
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Movement on the ETC of electrons from PsysII to Psysy moves H+ from ...
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- stoma into the thylakoid membrane space
- this creates the concentration gradient across the membrane |
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ATP Synthase Complex (function)
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- concentration gradient drives H+ across the membrane through the ATP synthase
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ATP Synthase Complex (production of ATP)
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- ATP synthase couples the flow of H+ to the phosphorylation of ADP
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cellular respiration --> oxidative phosphorylation as photosynthesis -->
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- photophosporylation
- initial energy input is light energy |
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Energy source for the light reaction? (what is the ATP created by the pumping of the ATP synthase of H+ from the inner thylakoid space to the stoma... made of?)
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- solar energy
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Difference between where electrons end up and in what configurations... (light reaction vs cellular respiration)
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- light reaction final electron acceptor is NADPH and is a high energy molecule
in cellular respiration O2 is the final electron acceptor and H20 is created as a low energy wast product |
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Two products of the light reaction
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NADPH and ATP
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Calvin Cycle Brief
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- food making process
- uses CO2 + ATP + NADPH - constructs energy glyceraldehyde - 3- phosphate (G3P) |
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G3P
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- end product of Calvin cycle
- makes organic molecules vital for the organism |
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what does it take to make G3P in the Calvin Cycle
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- 3 CO2 fixations
- 6 ATP - 6 NADPH |
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Calvin Cycle Step 1
Carbon Fixation - ______ (enzyme) -->. combines _____ with a 5 carbon sugar called ribulose biphosphate (RuBP) - RuBP + CO2 is unstable and breaks into a 3 carbon sugar 3PGA |
- rubisco
- CO2 |
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what is created a the end of carbon fixation ?
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- for 3 CO2 fixated => 6 3PGA
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What do the organism want from the Calvin Cycle
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3GP
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Calvin Cycle Step Step 2
Reduction Two chemical reactions consume energy from 6 ATP and oxidize 6 NADPH. - producing 6 molecules of G3P |
- 6 ATP consumed
- 6 NADPH - 6 3GP (energy rich ) |
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Calvin Cycle Step 3
Release of one molecule of G3P |
- five of the G3P remain in cycle
- a single G3P is the net product of photosynthesis |
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Calvin Cycle Step 4
Regeneration of RuBP |
- series of chemical reactions
- uses 3 ATP to arrange 5 G3P (15 carbon molecules) to form 3 RuBP - resets the cycle |
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The production of sugar from the reduction of CO2 is an emergent property of....
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the structural arrangement of a chloroplast, which integrates two stages of photosynthesis
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