Photosystem

Definition

A photosystem is a protein complex in the thylakoid membrane of chloroplasts that absorbs light during photosynthesis. It includes a reaction center and several light-harvesting complexes.

5 Must Know Facts For Your Next Test

1. There are two types of photosystems: Photosystem I (PSI) and Photosystem II (PSII).
2. Photosystem II absorbs light best at a wavelength of 680 nm, while Photosystem I absorbs best at 700 nm.
3. Photosystems play a crucial role in the light-dependent reactions by converting solar energy into chemical energy.
4. The primary function of PSII is to split water molecules, releasing oxygen and electrons.
5. Electrons excited in PSII travel through an electron transport chain to PSI, helping generate ATP and NADPH.

Review Questions

• What are the main components of a photosystem?
• How do Photosystem I and Photosystem II differ in their absorption wavelengths?
• What is the primary function of Photosystem II in the light-dependent reactions?

Related terms

Thylakoid membrane: The site within chloroplasts where the light-dependent reactions take place.

Electron transport chain: A series of protein complexes that transfer electrons from PSII to PSI, generating an electrochemical gradient used to produce ATP.

ATP Synthase: An enzyme embedded in the thylakoid membrane that synthesizes ATP as protons flow through it.