Describe the ultrastructure of a chloroplast.

Explanation

Chloroplast are the main site of photosynthesis.
1. It is a double wall membrane bounded organelles, discoid or lens shaped, `4 - 10 umm` is diameter and `1 - 33 umm` is thickness.
2. The proteinaceous matrix is called stroma.
3. A sac like membranous system called thylakoid is present in stroma and are arranged one above the other like a stack called granum 40-80 grana occur in each granum .
4 . Fret membrane connects grana .
5 PSI is located is outer thylakoid membrane facing stroma and PSII is located on inner membrane towards the lumen of thylakoid .
6. Chloroplast contains 30 - 35 prteins 20 - 30 % phospholipids 5-10 % chlorophyl caroteroids , 70s Ribosomes , circular DNA and starch grain .
7. Inner surface of lamelllar membrane consists of small spherical structures called quantosomes .
8. Due to presence to 70 s Ribosome and DNA they are considered to be semi autonomous organelles .
9 . Thylakoids contain pigment systems which help in light reaction of Photosynthesis .
Stroma contains enzymes for dark reaction.