Chloroplast

Definition

Chloroplasts are organelles found in plant cells and certain algae that conduct photosynthesis. They convert light energy into chemical energy stored in glucose.

5 Must Know Facts For Your Next Test

1. Chloroplasts contain their own DNA, which suggests they originated from endosymbiotic cyanobacteria.
2. The primary pigment in chloroplasts responsible for capturing light energy is chlorophyll.
3. Photosynthesis occurs in two main stages within the chloroplast: the light-dependent reactions and the Calvin cycle (light-independent reactions).
4. Thylakoids, arranged in stacks called grana, house the machinery for the light-dependent reactions of photosynthesis.
5. Stroma, the fluid-filled space surrounding the thylakoids, is where the Calvin cycle takes place.

Review Questions

• What is the primary function of chloroplasts?
• Name the two main stages of photosynthesis that occur within chloroplasts.
• Where in the chloroplast do the light-dependent reactions take place?

Related terms

Mitochondrion: An organelle involved in cellular respiration and energy production.

Thylakoid:

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

Stroma:

The fluid-filled area of a chloroplast outside the thylakoid membranes where the Calvin cycle takes place.