University:
Loyola University Maryland
Course:
BL 111 | Environmental Biology
Academic year:

2024
Views:

483

Pages:

2
Author:

Natasya J.

Plastids Plastids are double membrane organelles which are found in plant cells only. They are usually spherical or discoal in shape and their average size is 4 to 6 pm. A plastid shows two distine segions - grana and stroma. Grand are stacks membrane-bound, flattened. discold sacs containing chlorophyll molecules. These more cures are responsible for the production of tood by the process of phoo syn thens. They are, therefore, called "Kitclien of the cell". They are the main functional units of the chloroplost. The homogenous matrix in which Grana are embedded is known as Stroma. A variery of photosynthetic enzymes and starch grauns are present in the stroma. The stroma is colourless, whereas the Grann contains the pigments. Plastids are living and multiply by division of the pre- existing plastids called Proplastids. Plastids are of three types: 1) Leucoplasts Are colorless plastids. They store the food of the plant body in the form of starch, protein and lipids. They occur most commonly on the storage cells of roots and underground stems. • . 2.) Chloroplasts Are green plasteds because of the presence of clorophyll. Chloroplasts occur abundanly i green leaves, and alcu to some extent un green parts of the shoot 3.) Chromoplasts Are vamously colored plastids. They are mostly present in flowers and fruits. Function: (.) By trapping solas energy, green plasted sprano faclure Good through photo cynthers 2.) Chromaplarts are provide colored to various Flowering parts. 3.) Leucoplasts help in storage of protein, starch, and oil