Lecture Notes on Photosynthesis

Introduction

• Daydreaming about special abilities of organisms.
• Fascination with plant ability: photosynthesis.
• Importance of photosynthesis:
  • Produces oxygen, essential for animals and amoebas.
  • Plants as major producers in food webs.
  • Source of medications and food.

Glucose Production in Plants

• Plants produce their own glucose via photosynthesis.
• Photosynthesis equation similar to aerobic cellular respiration.
• Cellular respiration produces ATP, used by both plants and animals.

Photosynthesis Process

• Plants and some bacteria/protists perform photosynthesis.
• Photosynthesis consists of light-dependent and light-independent reactions.

Light-Dependent Reactions

• Occur in thylakoids within chloroplasts.
• Light captured, water is split (H2O → electrons + protons + oxygen).
• Produces oxygen, ATP, and NADPH.

Light-Independent Reactions (Calvin Cycle)

• Occurs in stroma, outside thylakoids.
• Involves carbon dioxide fixation through stomata.
• Uses ATP and NADPH from light-dependent reactions.
• Produces glucose from CO2, ATP, and NADPH.

Pigments and Light Capture

• Chlorophyll captures light (absorbs red/blue, reflects green).
• Other pigments absorb different wavelengths, accounting for plant color diversity.

Adaptations in Photosynthesis

• Plants have adaptations to photosynthesize in various environments:
  • Leaf shapes, coverings, and pigments.
• Example: CAM Photosynthesis in cacti:
  • Open stomata at night to capture CO2.
  • Store CO2 chemically for use during the day.

Conclusion

• Photosynthesis is a complex and fascinating process.
• Further exploration can include photosystems in light-dependent reactions and detailed Calvin cycle pathways.
• Plants’ adaptations to efficiently perform photosynthesis in different environments.