Question

What are plastids? How are they classified?

Answer 1

Plastid is a membrane-bound organelle found in the cell of plants, algae and few eukaryotic cells.

It the site of production and storage of important chemical compounds which are used by the cells of autotrophic organisms.

These are classified on the basis of the type of pigment present inside it.

The types of plastid are-

1) Chloroplasts:- are the green plastids which contain chlorophyll pigments for photosynthesis.

2) Chromoplasts:- are the coloured plastids for pigment synthesis and storage.

The pigment present in them is carotene which gives a different colour to fruits and flowers.

3) Gerontoplasts:- are the chloroplasts that are going through the ageing process.

These are present in the leaves in which no more photosynthesis occurs (such as in the fall months).

4) Leucoplasts: are the colourless plastids for monoterpene synthesis found in non-photosynthetic parts of the plants.

They are of three types:-

a) Amyloplasts- stores starch.

b) Proteinoplasts- stores proteins.

c) Elaioplasts- stores fats and oils.