Ultra-structure of Chloroplast
Ultra-structure of Chloroplast (site of photosynthesis) Introduction- Schimper(1883) coined the term chloroplast for green plants. The process of photosynthesis takes place in green plastids called chloroplasts (Cholos-green & Plastos-moulded). Chloroplast are present in mesophyll cells of leaf. Shape- chloroplasts are spherical, oval or disc shaped in higher plants. The shape varies in algae. Exam- Spirogyra -spiral shaped, Zygnema -star shaped, Ulothrix -girdle. Size- chloroplast measure about 4-10 μm in length, 1-5 μm broad and 2-4 μm in thickness. Number- in some algal cells there is only single chloroplast. In higher plants the number is large. There are 20-40 chloroplast in each cells. Distribution- chloroplast are evenly distributed throughout the cytoplasm. Chemical composition- chloroplast contain 50-60% protein, 23-25% phospholipids, 5-10% chlorophyll, 2-3% RNA, 1-2% other pigments, .5% DNA, vitamins and metal ions in traces.