IB Biology Topic B2.2.5: Adaptations of the Chloroplast for Photosynthesis Notes

The Chloroplast: Where Photosynthesis Happens

1. The chloroplast is a double-membrane organelle found in the cells of plants and algae.
2. It is the site of photosynthesis, which converts light energy into chemical energy stored in organic molecules.
   1. Like the mitochondrion, every structural feature of the chloroplast relates directly to its function.
3. The chloroplast has three distinct compartments.
   1. The thylakoid lumen is the space inside the thylakoid membranes.
   2. The stroma is the fluid between the thylakoids and the inner membrane.
   3. The intermembrane space lies between the outer and inner membranes.
4. This compartmentalisation lets different stages of photosynthesis run at the same time under optimal conditions.

Thylakoid Membranes and Grana: Maximising Light Absorption

1. The thylakoid membranes are the site of the light-dependent reactions.