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Photosynthesis. Chapter 6. Vocabulary—Breaking Down The Definitions. Photosynthesis Light Reactions Thylakoids Grana Stroma Photosystem Primary electron acceptor Electron transport chain Pigment Chloroplast Calvin cycle Carbon fixation. Photosynthesis—What Do We Already Know?.
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Photosynthesis Chapter 6
Vocabulary—Breaking Down The Definitions • Photosynthesis • Light Reactions • Thylakoids • Grana • Stroma • Photosystem • Primary electron acceptor • Electron transport chain • Pigment • Chloroplast • Calvin cycle • Carbon fixation
Photosynthesis—Obtaining Energy • Autotrophs use the process of photosynthesis to convert light energy into organic compounds.
Overview Photosynthesis • Water • Carbon Dioxide • Sunlight/Photons • Chloroplast • Light Reactions • Photosystem II • Cytochrome Complex • ATP Synthase • Photosystem I • Dark Reactions/Calvin Cycle • Phase 1-Carbon Fixation • Reduction • Regeneration
Inside a Chloroplast • Photosynthesis takes place inside a chloroplast • The chloroplast contains saclike membranes called THYLAKOIDS • THYLAKOIDS are arranged in stacks called GRANA • The Chlorophyll is inside the thylakoids • The STROMA is the region outside of the thylakoids
Light Reactions • The first stage of photosynthesis is the LIGHT REACTIONS. • Light is absorbed by the chloroplasts • Light Energy is converted to Chemical Energy (stored in ATP and NADPH)
Light Reactions Continued • Oxygen is given off during this reaction. • Chlorophyll in the chloroplast contains pigments (compounds that absorb light) that absorb a lot of blue and red light but reflect green light (giving plants their green color.
Light Reactions Continued • An oxidation reaction takes place, losing electrons and the primary electron acceptor takes on the lost electrons in a reduction reaction. • The primary electron acceptor donates the electrons to a series of molecules in the thylakoid membrane of the chloroplast.
Light Reactions Continued • These molecules are called an electron transport chain. • As the electrons pass through the chain they lose energy. • Light is absorbed at this point and the electrons combine with a proton and NADP+ • NADP+ is then reduced through another reduction reaction to NADPH.
Making ATP in Light Reactions • ATP is the energy in cells. • The movement o protons into the stroma of the chloroplast releases energy, which is used to produce ATP. • The energy is harnessed by an enzyme, ATP Synthase, which is in the thylakoid membrane
INTERACTIVE • 100-200 Words • Summarize the LIGHT REACTIONS of photosynthesis
Light Reactions Video Clips • Add to your summary if you need to!
Dark Reactions/Calvin Cycle • In the second set of reactions in photosynthesis plants use the energy that was stored in ATP and NADPH during the light reactions to produce sugars. • Most common way this is done is called the CALVIN CYCLE. • Calvin Cycle Song!
Calvin Cycle • A series of enzyme-assisted chemical reactions that produce a 3-Carbon Sugar. • Occurs in the STROMA of the chloroplast.
4 Steps of the Calvin Cycle Step 1 • 3 CO2 molecules diffuse into the stroma and combine with a 5-Carbon molecule, RuBP. This molecule is very unstable and it quickly splits into 2 3-Carbon molecules called 3-PGA. • Each 3-PGA is converted into another 3 Carbon molecule, G3P after receiving a phosphate group from ATP and a proton from NADPH. Step 2
4 Steps of the Calvin Cycle Step 3 • One of the G3P molecules leave the Calvin Cycle to make carbohydrates which are stored for later use. • The remaining 3GP molecules are converted back into RuBP by adding phosphate groups from ATP and then the Calvin Cycle begins again. Step 4
Step 1—3 CO2 molecules combine to form RuBP (6 carbon molecule) which splits into 3 PGA Step 4– The rest of the G3P is converted back into RuBP/Rubisco Calvin Cycle Step 3– One molecule of G3P leaves the cycle to make sugars Step 2—Each molecule of 3 PGA is converted to G3P
