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Photosynthesis. Chapter 8. Vocabulary—Breaking Down the Definitions. Photosynthesis Pigment Chlorophyll Thylakoid Stroma NADP+ Light Dependent Reactions ATP Synthase Calvin Cycle. Photosynthesis—What Do We Already Know?. Photosynthesis Brain Pop.
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Photosynthesis Chapter 8
Vocabulary—Breaking Down the Definitions • Photosynthesis • Pigment • Chlorophyll • Thylakoid • Stroma • NADP+ • Light Dependent Reactions • ATP Synthase • Calvin Cycle
Photosynthesis • Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into oxygen and high-energy sugars.
Light and Pigments • In addition to water and carbon dioxide, photosynthesis also requires LIGHT and CHLOROPHYLL. • CHLOROPHYLL= a molecule within a chloroplast • Chlorophyll is a pigment that absorbs light
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. --Leaf Demo-- • 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.
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!
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
Factors Affecting Photosynthesis • Water, Temperature, Intensity of Light all affect the rate of photosynthesis
Thinking Visually • Complete the flowchart on page 216 of your book.