07_Lecture_Presentation

Introduction to Photosynthesis

• Poison ivy contains urushiol, a chemical causing itchy blisters.

• All plants, including poison ivy, produce energy through photosynthesis, converting light energy into chemical energy of sugar.

Importance of Photosynthesis

• Photoautotrophs: Organisms like plants, algae, and certain bacteria that produce food.

• Heterotrophs: Consumers that rely on other organisms for food.

Chloroplast Structure

• Photosynthesis occurs in chloroplasts, which have:

  • Double membrane

  • Stacks of thylakoids

  • Thick fluid called stroma

• Chlorophyll: A pigment that absorbs light energy essential for converting solar energy into chemical energy.

Photosynthesis Process

Redox Reactions

• Photosynthesis is a redox process where water (H2O) is oxidized and carbon dioxide (CO2) is reduced.

Two Stages of Photosynthesis

1. Light Reactions

   • Occur in thylakoids.

   • Produce ATP and NADPH.

2. Calvin Cycle

   • Takes place in the stroma.

   • Fixes CO2 into organic compounds.

The Light Reactions

• Light energy converts to chemical energy (ATP and NADPH) using:

  • Photosystems: Complexes in thylakoid membranes capturing solar energy.

  • Electron Transport Chain: Transfers energy from photosystem II to photosystem I, producing ATP and NADPH.

The Calvin Cycle

• Stages of the Calvin Cycle:

  • Carbon Fixation

  • Reduction

  • Releasing G3P

  • Regeneration of RuBP

• Uses ATP and NADPH to construct G3P for glucose synthesis.

Global Significance of Photosynthesis

• Provides food and oxygen for almost all living organisms.

• Sugars made by photosynthesis are basic sources for building other organic molecules.

Impact of Rising CO2 Levels

• Studies assess effects of increased CO2 on plants, focusing on growth and ecosystem health.

Climate Change Awareness

• Reductions in fossil fuel use and deforestation may help moderate climate change effects.

Key Takeaways

• Understanding the roles and processes of photosynthesis is crucial for addressing environmental challenges and sustaining life on Earth.