P680 and P700 are the reaction centers of the two photosystems involved in photosynthesis. They are named based on the wavelengths of light they absorb most effectively.
Reaction Centers in Photosynthesis
The process of photosynthesis involves two main photosystems: Photosystem I and Photosystem II. Each photosystem contains a reaction center, where the critical electron transfer process occurs. These reaction centers are specialized chlorophyll molecules that are fundamental to capturing light energy and converting it into chemical energy.
P680
- Location: The reaction center of Photosystem II.
- Light Absorption: P680 absorbs light most strongly at a wavelength of 680 nanometers.
- Function: Upon absorbing light, P680 loses an electron, initiating the electron transport chain within Photosystem II. This electron is crucial for generating the proton gradient necessary for ATP synthesis. The reference states that the reaction centers are named for the wavelength of light that causes the maximum loss of electrons from the reaction center pigments.
P700
- Location: The reaction center of Photosystem I.
- Light Absorption: P700 absorbs light most strongly at a wavelength of 700 nanometers.
- Function: After light absorption, P700 also loses an electron which is then passed along the electron transport chain in Photosystem I. This electron transfer is vital for the reduction of NADP+ to NADPH.
Summary Table
| Reaction Center | Photosystem | Peak Absorption Wavelength | Primary Function |
|---|---|---|---|
| P680 | II | 680 nm | Initiates electron transport in Photosystem II, contributing to the proton gradient for ATP synthesis. |
| P700 | I | 700 nm | Initiates electron transport in Photosystem I, vital for the reduction of NADP+ to NADPH. |
In essence, both P680 and P700 are essential for photosynthesis, each playing a crucial role in capturing light energy and converting it into chemical forms of energy that support plant growth.
