Photosynthesis

4.1 How do living things get ATP? ATP is the energy carrier in living things – it is usable energy for the cell (chemical potential energy). ATP stands for Adenosine triphosphate. Living things get ATP from breaking down carbon based molecules. (carbohydrates & lipids) Starch molecule Glucose molecule

This is how it works phosphate removed

PHOTOSYNTHESIS Autotrophic Process: Plants and some bacteria (producers) take light energy from the sun and store it as chemical energy (glucose) Energy is stored as carbohydrate (CPE) in seeds and bulbs Equation: 6CO 2 + 6H 2 O (+ sunlight)  C 6 H 12 O 6 + 6O 2

PHOTOSYNTHESIS Absorbing Light Energy Pigments: Absorb different colors of white (visible) light (ROY G BIV) Main pigment: Chlorophyll a Accessory pigments: Chlorophyll b and Carotenoids These pigments absorb all wavelengths (light) BUT green

PHOTOSYNTHESIS Why do we see green? Green color from white light reflected (NOT absorbed) Chloroplast: organelle responsible for photosynthesis Chlorophyll: located within chloroplast Green pigment

STOP & REVIEW What are the three inputs (reactants) required for photosynthesis to begin? (use chemical formulas when possible)? 1.Light 2.6H 2 O 3.6CO 2 What are the two outputs (products) of photosynthesis? 1.6O 2 2.C 6 H 12 O 6 In what organelle does photosynthesis take place? 1.chloroplast What pigment is contained in that organelle? 1.chlorophyll What are the stack like structures called in that organelle? 1.thlakoids What is the liquid part called inside that organelle? 1.stroma

PHOTOSYNTHESIS Photosynthesis has 2 phases: Light-dependent reaction: converts light energy into chemical energy; produces ATP & NADPH (energy carriers) to be used to fuel light-independent reaction. Steps: Photosystem II, ETC, Photosystem I. Light-independent reaction: uses ATP & NADPH produced in light-dependent reaction and fixes carbon from CO 2 to make simple sugars (glucose).

PHOTOSYNTHESIS Light-dependent reaction (LIGHT Reaction) 1. Requires light 2. Occurs in chloroplast (in thylakoids) Thylakoids: membrane enclosed compartments; membrane contains chlorophyll & other light-absorbing molecules. Granum (grana): stacks of thylakoids 3. Chlorophyll (thylakoid) traps energy from light 4. Light excites electron (e-) Kicks e- out of chlorophyll to an electron transport chain Electron transport chain: series of proteins in thylakoid membrane (like a bucket brigade)

PHOTOSYNTHESIS 5. Energy “lost” along electron transport chain 6. “Lost” energy used to recharge ATP from ADP ATP synthase: a complex enzyme that makes ATP by adding phosphate groups to ADP. 7. NADPH produced from e- transport chain NADP + accepts electrons to become NADPH Stores energy until transfer to stroma Plays important role in light-independent reaction Has ability to donate e- Total byproducts: ATP, NADPH, O 2

PHOTOSYNTHESIS How did we get O 2 as a byproduct?! Photolysis: replaces electrons lost from chlorophyll by splitting water into oxygen, hydrogen ions, and electrons. Oxygen is released during the light dependent reaction

Chlorophyll passes energy down through the electron transport chain. for the use in light-independent reactions bondsP to ADP forming ATP oxygen released splits H 2 O H+H+ NADP + NADPH Light energy transfers to chlorophyll. Energized electrons provide energy that At each step along the transport chain, the electrons lose energy. This energy is used to make NADPH and ATP for the light independent reactions.

STOP & REVIEW LIGHT DEPENDENT REACTION What is the first thing that is required to start this part of the reaction? 1.Light Where does this part of the reaction occur? 1.Chloroplast - thylakoids What traps the energy from the light? 1.Chlorophyll The light excites _________ and kicks them out of chlorophyll to an ___________ __________ ________? 1. Electrons, Electron Transport Chain The energy that is lost along that chain is used to recharge ADP into ______ and NADP into ________. 1. ATP and NADPH What is made at the end of this reaction that is used to run the next reaction? 1. ATP, NADPH What is made and released during this part of the reaction? 1. Oxygen

PHOTOSYNTHESIS Light-independent reaction (Dark Reaction, Calvin Cycle) 1. Does not require light 2. Occurs in stroma of chloroplasts Stroma: The fluid outside of the thylakoids. 3. Requires CO 2 4. Uses ATP and NADPH as fuel to run 5. Makes glucose (sugar) from CO 2 and Hydrogen End Products: glucose, NADP +, ADP

Overall chemical equation of photosynthesis: 6CO 2 + 6H 2 O  C 6 H 12 O 6 + 6O 2 Overall energy transformation of photosynthesis: Light/Radiant energy  Chemical potential energy

STOP & REVIEW (DARK REACTION) 1. Why is this part called the dark reaction? 1.It does not require light. 2. What are the other names for this part of the reaction? 2. Calvin Cycle, Light Independent 3. Where does this part of the reaction occur? 3.Stroma 4. What is needed from the reactants to start the dark reaction? 4.Carbon dioxide 5. What is needed from the first reaction to run this part of the reaction? 5.ATP, NADPH 6. What is made in the dark reaction using carbon dioxide and hydrogen? 6.Glucose 7. What are the final products of the dark reaction? 7.Glucose, ADP, NADP

PHOTOSYNTHESIS What affects photosynthesis? Light intensity: as light increases, rate of photosynthesis increases

PHOTOSYNTHESIS What affects photosynthesis? Carbon Dioxide: As CO 2 increases, rate of photosynthesis increases

PHOTOSYNTHESIS What affects photosynthesis? Temperature: Temperature Low = Rate of photosynthesis low Temperature Increases = Rate of photosynthesis increases If temperature too hot, rate drops

Check it! 1.The process that uses the sun’s energy to make simple sugars is _____________. A.Cellular respiration B.Glycolysis C.Photosynthesis D.Photolysis

Check it! 2.The function accomplished by the light- dependent reactions is ______________. A.Energy storage B.Sugar production C.Carbon fixation D.Conversion of sugar