Miss Angler's Biology Class: Photosynthesis

Overview

• Focus on photosynthesis, specifically:
  • Light-dependent phase
  • Light-independent phase (Calvin cycle)
• Importance of understanding the photosynthesis equation
  • Components required: Carbon dioxide, water, sunlight, chlorophyll
  • Products: Glucose, oxygen

Photosynthesis Equation

• Balanced equation is preferred for accuracy:
  • Carbon dioxide + Water + Sunlight + Chlorophyll → Glucose + Oxygen
• Sunlight and chlorophyll are crucial, although not "materials"

Chloroplast Structure

• Understanding chloroplast, thylakoids, and stroma is essential:
  • Light-dependent reaction occurs in the thylakoids
  • Calvin cycle occurs in the stroma

Light-Dependent Phase

• Occurs during the day in the thylakoids
• Process:
  • Photolysis: Splitting of water into hydrogen and oxygen using sunlight
  • Oxygen is released as a by-product
  • Hydrogen and electrons are used to produce:
    • NADPH (hydrogen carrier)
    • ATP (energy carrier)
• Purpose: Produces energy and building blocks (hydrogen) for the Calvin cycle

Light-Independent Phase (Calvin Cycle)

• Occurs at night or in low light, in the stroma
• Does not require light
• Process:
  • Starts with ribose biphosphate (RuBP) combining with carbon dioxide
  • Forms an unstable 6-carbon compound, which breaks into two 3-carbon PGAs
  • ATP provides energy, while NADPH provides hydrogen
  • Resulting PGAL molecules can become glucose or regenerate RuBP
• Complexity increases with advanced study levels

Key Processes and Terms

• Photophosphorylation: Using light to attach a phosphate to ADP, forming ATP
• NADPH and ATP: Key products from the light-dependent phase used in the Calvin cycle

Cycle Recap

• ATP and NADPH are regenerated through their cycle
• Plants require a photo period for photosynthesis to occur

Terminology Recap

• Photolysis: Cutting water with light
• NADPH: Hydrogen carrier
• Photophosphorylation: Attaching phosphate using light
• RuBP: Starting molecule for Calvin cycle
• PGAL: Intermediate in glucose formation

Conclusion

• Continuous cycle of energy and substance production
• Importance of sunlight in sustaining the cycle

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