Biology: Photosynthesis

Overview of Photosynthesis

• Definition: Process by which plants, algae, and some bacteria convert light energy from the sun into chemical energy in the form of organic compounds, such as glucose.
• Importance: Produces oxygen and organic compounds necessary for life on Earth.

Light-Dependent Reactions

• Occur in the thylakoid membranes of the chloroplast
• Light energy is absorbed by pigments such as chlorophyll and converted into ATP and NADPH
• Two stages:
  1. Light-harvesting complexes absorb light energy
  2. Electron transport chain generates ATP and NADPH

Light-Independent Reactions (Calvin Cycle)

• Occur in the stroma of the chloroplast
• Use ATP and NADPH produced in light-dependent reactions to convert CO2 into glucose
• Three stages:
  1. Carbon fixation: CO2 is fixed into a 3-carbon molecule
  2. Reduction: 3-carbon molecule is reduced to form glyceraldehyde 3-phosphate
  3. Regeneration: Glyceraldehyde 3-phosphate is regenerated to form RuBP, the 5-carbon molecule necessary for carbon fixation

Factors Affecting Photosynthesis

• Light intensity: Increased light intensity increases photosynthesis rate
• Temperature: Optimal temperature range for photosynthesis is between 20-30°C
• Water availability: Photosynthesis requires adequate water supply
• CO2 concentration: Increased CO2 concentration can increase photosynthesis rate

Types of Photosynthesis

• Oxygenic photosynthesis: Produces oxygen as a byproduct, occurs in plants, algae, and cyanobacteria
• Anoxygenic photosynthesis: Does not produce oxygen, occurs in some bacteria

Importance of Photosynthesis

• Produces oxygen necessary for aerobic respiration
• Provides energy and organic compounds for food chains
• Supports aquatic life through phytoplankton production

Photosynthesis

• Definition: Process that converts light energy into chemical energy, producing organic compounds like glucose.

Light-Dependent Reactions

• Occur in thylakoid membranes of chloroplasts
• Absorb light energy through pigments like chlorophyll
• Produce ATP and NADPH through two stages:
  • Light-harvesting complexes absorb light energy
  • Electron transport chain generates ATP and NADPH

Light-Independent Reactions (Calvin Cycle)

• Occur in stroma of chloroplasts
• Use ATP and NADPH to convert CO2 into glucose through three stages:
  • Carbon fixation: CO2 is fixed into a 3-carbon molecule
  • Reduction: 3-carbon molecule is reduced to form glyceraldehyde 3-phosphate
  • Regeneration: Glyceraldehyde 3-phosphate is regenerated to form RuBP, a 5-carbon molecule

Factors Affecting Photosynthesis

• Light intensity: Increased light intensity increases photosynthesis rate
• Temperature: Optimal temperature range is between 20-30°C
• Water availability: Photosynthesis requires adequate water supply
• CO2 concentration: Increased CO2 concentration can increase photosynthesis rate

Types of Photosynthesis

• Oxygenic photosynthesis: Produces oxygen, occurs in plants, algae, and cyanobacteria
• Anoxygenic photosynthesis: Does not produce oxygen, occurs in some bacteria

Importance of Photosynthesis

• Produces oxygen necessary for aerobic respiration
• Provides energy and organic compounds for food chains
• Supports aquatic life through phytoplankton production