The interconnected flattened sacs within the inner membrane of the chloroplast are called thylakoid. Many thylakoids are come together and get arranges in a stack called a granum.
Thylakoid contains chlorophyll pigment and is responsible for absorbing the sunlight and conducting light reaction. These thylakoids or grana are suspended in a liquid called the stroma.
The stroma contains the enzymes which are required in the light-dependent reaction. It contains DNA, ribosome, starch. The synthesis of organic molecules occurs in the stroma.
