Photosynthesis Process

Study Notes

Light-dependent Reactions

Occur in the thylakoid membranes of the chloroplast
Light energy is absorbed by pigments and converted into ATP and NADPH
Two stages:
1. Light absorption: Light energy is absorbed by pigments such as chlorophyll and other accessory pigments
2. Electron transport: Energy from light is used to generate a proton gradient, which drives the synthesis of ATP and NADPH
Produces ATP and NADPH, which are used in the Calvin Cycle

Calvin Cycle

Occurs in the stroma of the chloroplast
Uses ATP and NADPH produced in the light-dependent reactions to convert CO2 into glucose
Three stages:
1. Carbon fixation: CO2 is fixed into a 3-carbon molecule using the enzyme RuBisCO
2. Reduction: The 3-carbon molecule is reduced to form glyceraldehyde 3-phosphate (G3P) using ATP and NADPH
3. Regeneration: The G3P molecules are used to regenerate the RuBP molecule, allowing the cycle to continue
Produces glucose, which is used by the plant to fuel growth and development

Pigments and Chlorophyll

Pigments: Molecules that absorb light energy and transfer it to the reaction centers
Chlorophyll: The most important pigment in photosynthesis, responsible for absorbing light energy and transferring it to the reaction centers
- Chlorophyll a: Absorbs light in the blue and red parts of the visible spectrum
- Chlorophyll b: Absorbs light in the blue-violet part of the visible spectrum
Accessory pigments: Pigments that absorb light energy and transfer it to chlorophyll
- Carotenoids: Absorb light in the blue and red parts of the visible spectrum
- Phycobiliproteins: Absorb light in the blue part of the visible spectrum
Action spectrum: A graph showing the rate of photosynthesis at different wavelengths of light, peaking at the wavelengths absorbed by chlorophyll and other pigments

Description

Understand the light-dependent reactions and Calvin cycle, including the role of pigments and chlorophyll in photosynthesis. Learn about the stages of carbon fixation, reduction, and regeneration in the Calvin cycle.