Chloroplast
Structure: Chloroplasts are structures in which photosynthesis takes place. In each cell, there are 40-50 of these disk shaped organelles. Chloroplasts are surrounded in two membranes and contain a ground substances called the stroma, which is crossed by connected sacs called lamelles.
Function:Molecules of chlorophyll connected to the lamelles, trap light for photosynthesis. This energy is then made into a substance called ATP, or adenosine triphosphate, by a series of chemical reactions in the grana. The grana are the stacks of lamelles that make up the double membrane. Chloroplasts also have small grains of starch that can be used to store glucose for small periods of time.
