Chloroplast: They possesses green pigments named chlorophyll in excess as aresult they are green. Other pigments are also present to some extent. Every cell may contain one or more chloroplast.
In higher plants the shapes of chloroplast is lenceolate. In Algal cells their shapes are of various types, e.g. cup shaped, spiral, reticulate, star shaped. semicircular etc.
Structure of chloroplast: The following parts make Chloroplast :
1. A bi-layered semipermiable membrane surrounds the whole chloroplast. It is composed of protein and lipid. This is called lipoprotein.
2. A hygroscopic matrix surrounded by a membrane is there. This matrix is called stroma.
3. In the stroma, 40-80 well-arranged barrel shaped grana (sing: granum) are present. In one granum there are 5-25 granum disc. Insidethe granum disc, there are spaces. Probably chlorophyll and other photosynthetic materials are present in this chamber.
4. Some granum discs of two adjacent grana are connected by minute tubular bodies, which are called stroma lamelli.
5. Many crystalline bodies are arranged in the membrane of grana disc. These are called quantosome. In the dark phase of photosynthesis, carbon-di-oxide isassimilated mainly in the quantosome.
Function: Its function is to prepare carbohydrate food by the process photosynthesis.