SITE OF PHOTOSYNTHESIS: Chloroplast

• Chloroplast is a double membrane bound structure and an outer and inner membrane is collectively called Peristromium.
• It encloses colorless, colloidal matrix called Stroma.
• It contains enzymes for reduction of CO₂ into glucose (dark reaction), 70S ribosomes and DNA.
• DNA is Circular, closed, naked ring and is called plastidome.
• Since the DNA is present, the Chloroplast is self-replicating and semi-autonomous cell organelle.

• Embeded in the stroma, there are approximately 40 to 60 green colored structures called Grana.
• Each granum consists of small, disc-like lamellae or Thylakoids.
• The Photosynthetic pigments are embed in the Thylakoids.
• ATP synthesis (light reactions) takes place in grana.
• Grana are interconnected by membranes called stroma lamellae or inter granal or fret membranes,
• The stroma lamella helps in rapid transport of materials.
• In prokaryotes, chloroplasts are absent and pigments are located in lamellae i.e. (Thylakoid).
• According to Park and Biggins, photosynthetic pigments are located in the membranes of Thylakoids in specific areas called Quantasomes.
• A quantasome is a photosynthetic unit. Later on. Emerson established the presence of two distinct groups, PS-I and PS-II.