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What is ATP?. Adenosine Tri-phosphate. Base. Phosphate Groups. Sugar. ATP. Exergonic. Endergonic. ADP. Catabolic and Anabolic Pathways depend on ATP / ADP shuttle. Figure 10.0 Sunbeams. Photosynthesis. Photoautotrophs. Question:. Where does photosynthesis take place?.
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Adenosine Tri-phosphate Base Phosphate Groups Sugar
ATP Exergonic Endergonic ADP
Figure 10.0 Sunbeams Photosynthesis
Question: • Where does photosynthesis take place?
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Leaf Anatomy
Chloroplast Mesophyll Cell Stoma Plants • Autotrophs: self-producers. • Location: 1. Leaves a. stoma b. mesophyll cells
Oxygen (O2) Carbon Dioxide (CO2) Guard Cell Guard Cell Stomata (stoma) • Pores in a plant’s cuticle through which water and gases are exchanged between the plant and the atmosphere.
Nucleus Cell Wall Chloroplast Central Vacuole Mesophyll Cell
Stroma Outer Membrane Thylakoid Granum Inner Membrane Chloroplast • Organelle where photosynthesis takes place.
Thylakoid Membrane Thylakoid Space Granum Thylakoid
Chloroplast • Chlorophyll – green pigment located inside chloroplasts • Found in mesophyll (interior of leaf) • Double membrane • Enclose stroma (dense liquid) containing grana made up of thylakoid membranes which contain chlorophyll
Photosynthesis Overview
Photosynthesis + H2O CO2 Energy ATP and NADPH2 Which splits water Light is Adsorbed By Chlorophyll Calvin Cycle ADP NADP Used Energy and is recycled. Chloroplast O2 + C6H12O6 Light Reaction Dark Reaction
SUN photons glucose Photosynthesis • An anabolic, endergonic, carbon dioxide (CO2) requiring process that uses light energy (photons) and water (H2O) to produce organic macromolecules (glucose). 6CO2 + 6H2O C6H12O6 + 6O2
Question: • Why are plants green?
Chlorophyll Molecules • Located in the thylakoid membranes. • Chlorophyll have Mg+in the center. • Chlorophyll pigmentsharvest energy (photons) by absorbing certain wavelengths (blue-420 nmand red-660 nmare most important). • Plants are green because the greenwavelength is reflected, not absorbed.
violetbluegreenyelloworangered Absorption of Chlorophyll Absorption wavelength
Question: • During the fall, what causes the leaves to change colors?
Fall Colors • In addition to the chlorophyll pigments, there are other accessorypigments present. • During the fall, the green chlorophyll pigments are greatly reducedrevealing the other pigments. • Carotenoids are pigments that are either red or yellow.
Chromatography • Pigments can be separated out using the process of CHROMATOGRAPHY.
Reactions in Photosynthesis...
Redox Reaction • Thetransfer of one or more electronsfrom one reactantto another. • Two types: 1. Oxidation 2. Reduction
Oxidation 6CO2 + 6H2O C6H12O6 + 6O2 glucose Oxidation Reaction • The loss of electrons from a substance. • Or the gain of oxygen.
Reduction 6CO2 + 6H2O C6H12O6 + 6O2 glucose Reduction Reaction • The gain of electrons to a substance. • Or the loss of oxygen.
Breakdown of Photosynthesis • Two main parts (reactions). 1. Light Reaction or Light Dependent Reaction Produces energy from solar power(photons)in the form of ATP and NADPH.
Breakdown of Photosynthesis 2. Calvin Cycle or Light Independent Reaction or Carbon Fixation or C3 Fixation Uses energy(ATP and NADPH) from light rxnto make sugar (glucose).
Chlorophyll • Two different types : Chlorophyll a and b • “a” – main pigment in photosynthesis • “b” – accessory pigment • Both have similar structure but absorb different wavelengths of light
Chlorophyll absorbs light of a particular wavelength, electrons are excited and jump to higher energy level, drops back down and gives off heat • This energy is passed along until it finds Chlorophyll a, which, when excited, passes electron to primary electron acceptor…powering light dependent reactions.
How a photosystem harvests light.. Chlorophyll a Begins Light Reaction
1. Light Dependent Reaction • Occurs in the Thylakoid membranes • During the light reaction, there are two possibleroutes for electron flow. A. Photosystem II B. Photosystem I *Pigments of the thylakoid space organize themselves into groups called photosystems
For the sole purpose of confusing you.... Plants start photosynthesis by using photosystem II first
Photosystem II Two excited electrons are passed on to the primary electron acceptor
Splitting of water.. "Photolysis" Water split to release and replace electrons...
Electron Transport Chain Makes ATP... "Photophosphorylation"
Chemiosmosis • Powers ATP synthesis. • Located in the thylakoid membranes. • UsesETCand ATP synthase(enzyme) to make ATP. • Photophosphorylation: addition of phosphate to ADP to make ATP.
SUN (Proton Pumping) H+ H+ Thylakoid E T PS I PS II C high H+ concentration H+ H+ H+ H+ H+ H+ Thylakoid Space H+ ATP Synthase low H+ concentration ADP + P ATP H+ Chemiosmosis…Making ATP
Electron is passed to Photosystem I Electrons excited & sent on to e- acceptor
ETC to Ferredoxin Donates e- to NADP+ to make NADPH
Things to Remember…. Light Reactions… • Occur in the Thylakoid Membrane • Inputs are water and light • Products : ATP, NADPH and O2 • Oxygen produced comes from the water, not Carbon Dioxide! • Two different pathways…..
Cyclic vs. Noncyclic Pathways… • Noncyclic Light Reaction • Electrons taken from Chlorophyll a are not recycled back down to the ground state – therefore do not make it back to the chlorophyll molecule when the reaction is complete. Electrons end up on NADPH • Cyclic Light Reaction • Uses ONLY Photosystem I, sunlight hits P700 • Energy given off down ETC, only produces ATP