Plastids and Vacuoles

Tejinder Kaur, Academic Content Creator at Edumarz

Plastids –

• It is a double membrane bound cell organelle found in plant cells and algae.

• Their main role is to manufacture and store food.

• They also contain pigments that are used in the process of photosynthesis.

Types:

There are mainly three different types of plastids on the basis of absence or presence of pigments:

• Chloroplasts 

• Chromoplasts

• Leucoplasts

Chloroplasts –

• They are green colour biconvex shaped, double membrane cell organelle found in plant cells.

• Act as sites for synthesizing food by process of photosynthesis.

Chromoplasts –

• It is the name given to all the colour pigments plastids synthesized in plants.

• They are found in flowering plants, fruits and leaves.

• They have carotenoid pigments which impart colour.

Leucoplasts –

• They are colourless plastids.

• They are found in the non photosynthetic part of the plants.

• They act as storehouse for lipids, proteins and starches.

• It is of three types :

1. Amyloplasts – leucoplasts that store starch.

2. Proteinoplasts – leucoplasts that store protein.

3. Elaioplasts – leucoplasts that store fats and oils.

Vacuole –

• The term “vacuole” means “empty space”.

• Helps in storage and disposal of waste substances.

• The size of vacuole in plant cells are much larger than that of animal cells.

• They are single membrane and their membrane is named as tonoplast.

Functions :

• A vacuole stores minerals, salts, pigments and proteins in a cell.

• They are completely filled with water and exert a pressure on the cell wall. A pressure called as turgor pressure. This pressure helps in maintaining the shape of the cell.

• The substance are taken inside vacuole by process of endocytosis and expelled out by exocytosis.