Plastids are double membrane bounded semi autonomous cell organelle responsible to synthesise and store various types of organic compounds.
On the basis of structure, pigments and function, the plastids can be categorized into three types:
However, one form of plastid can change into another form. For example: In tomato the young ovary contains Leucoplasts which change into chloroplasts in young fruits and finally into Chromoplasts as food ripens.
As detailed description about chloroplasts have been provided in previous notes let us discuss about Chromoplasts over here .
Types of Chromoplasts (based on colouring pigments)
1) Phaeoplast (Gr: phaeo: dark or brown; plast: living)
They contain brown pigments (Xanthophyll and fucoxanthin). Eg: Brown algae, Diatoms.
They contain red pigment (R-phycoerythrin, R- phycocyanin. They are found in red algae.
They are found in blue green algae and contain c- phycocyanin, c- phycoerythrin and Chlorophyll-a. They are also found in purple photosynthetic bacteria.