Photosynthesis Overview

Overview of Photosynthesis

• Photosynthesis is the 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.

Light-Dependent Reactions

• Take place in the thylakoid membranes of chloroplasts
• Light energy is absorbed by pigments such as chlorophyll and converted into ATP and NADPH
• Water is oxidized, releasing oxygen as a byproduct

Light-Independent Reactions (Calvin Cycle)

• Take place in the stroma of chloroplasts
• Carbon dioxide is fixed into glucose using ATP and NADPH produced in the light-dependent reactions
• Regeneration of RuBP, the five-carbon sugar, is necessary for the cycle to continue

Overall Equation

• 6 CO2 + 6 H2O + light energy → C6H12O6 (glucose) + 6 O2

Factors Affecting Photosynthesis

• Light: intensity, quality, and duration affect photosynthetic rate
• Temperature: optimal temperatures vary among species, but generally between 20-30°C
• Water: availability and drought can limit photosynthesis
• CO2: concentration and availability can limit photosynthesis

Importance of Photosynthesis

• Provides energy and organic compounds for plants to grow and develop
• Supports aquatic food webs through phytoplankton
• Produces oxygen as a byproduct, essential for most living organisms