Reaction center

Definition

A reaction center is a complex of proteins and pigments in chloroplasts that initiates the light-dependent reactions of photosynthesis. It plays a crucial role in converting solar energy into chemical energy by transferring excited electrons to an electron transport chain.

5 Must Know Facts For Your Next Test

1. The reaction center contains specialized chlorophyll molecules known as P680 in Photosystem II and P700 in Photosystem I.
2. When photons strike the reaction center, they excite electrons to a higher energy state, initiating electron transfer processes.
3. Reaction centers are embedded within the thylakoid membranes of chloroplasts.
4. They are integral to both non-cyclic and cyclic photophosphorylation pathways.
5. The primary electron acceptor in the reaction center captures excited electrons before passing them along an electron transport chain.

Review Questions

• What role does the reaction center play in photosynthesis?
• Which specialized chlorophyll molecules are found in the reaction centers of Photosystem I and II?
• Where within the chloroplast can reaction centers be found?

Related terms

Photosystem I: Contains P700 chlorophyll molecules and is involved primarily in NADPH synthesis.

Photosystem II: Contains P680 chlorophyll molecules and is responsible for water splitting and O2 evolution.

Thylakoid Membrane: The site within the chloroplast where light-dependent reactions, including those involving reaction centers, occur.