Reaction center

Definition

The reaction center is a complex of proteins and pigments that plays a central role in the initial steps of photosynthesis by converting light energy into chemical energy. It is the site where photon absorption leads to the transfer of electrons.

5 Must Know Facts For Your Next Test

1. The reaction center contains chlorophyll molecules that absorb light energy.
2. It is found within the thylakoid membranes of chloroplasts in plants and cyanobacteria.
3. There are two types of reaction centers: Photosystem I (PSI) and Photosystem II (PSII).
4. The primary function of the reaction center is to initiate electron transport by transferring excited electrons to an acceptor molecule.
5. Photosystem II's reaction center, known as P680, absorbs light at a wavelength of 680 nm, while Photosystem I's reaction center, known as P700, absorbs light at a wavelength of 700 nm.

Review Questions

• What are the main components found in the reaction center?
• Explain the difference between Photosystem I and Photosystem II in terms of their absorption peaks.
• Describe the primary function of the reaction center in photosynthesis.

Related terms

Chlorophyll: A pigment involved in photosynthesis that captures light energy.

Thylakoid Membrane: A membrane-bound compartment inside chloroplasts where light-dependent reactions occur.

Electron Transport Chain: A series of protein complexes that transfer electrons via redox reactions to form an electrochemical gradient.