Question

Name the various types of plastids? Where do fat-soluble pigments occur?

Answer 1

Hint:-Plastids are cell organelles found in certain plant cells and algae. Ernst Hackel was the first person to discover this membrane-enclosed organelle. Its primary functions include storage of food or aid in photosynthesis etc. Plastids can be pigmented or contain no pigments. In plants, the pigmented plastids are exposed to the surface while colourless ones are not exposed to light.

Complete answer:
The proplastid differentiates to form various plastids with specific functions.
Chloroplasts: the presence of the green pigment chlorophyll in the plastid aids in the process of photosynthesis. In plants, the mesophyll layer of the leaves is abundant in chloroplasts. The chloroplasts that have aged are called gerontoplasts, they no longer perform photosynthesis.
Chromoplasts: are pigmented plastids; they give colour to various parts of the plant like the leaves, flowers, and fruits. The pigments present in the plastid are called carotenoids. The attractive colour of the various flowers generally attracts pollinating agents.
Leucoplast: these plastids contain no pigments; their main purpose is to store food. They are further divided into-
a) Amyloplast- these store starch or sugar. This type of plastid can be found in potato tuber
b) Proteoplast- these plastids store proteins. They are also known as aleuroplast. This type of plastid can be found in maize.
c) Elaioplast- stores fat. The plastid is found in seeds like groundnut.
The fat-soluble pigments are carotenoids and chlorophylls. These pigments are fat-soluble due to the presence of a long unsaturated hydrocarbon chain. Carotenoids are found in plants (gives colour to the leaves, flowers, etc.), algae (red algae for example), and bacteria (for example Staphylococcus aureus). Chlorophyll is abundant in green plants, certain algae, and bacteria.

Note:- Etioplasts are precursors of chloroplasts they have not been exposed to light. The chloroplasts that have aged are called gerontoplasts, they no longer perform photosynthesis. Red algae despite having chlorophyll are red in colour because of the accessory pigment phycoerythrin. Accessory pigments also absorb light and aid in photosynthesis.
Apart from the above state functions, plastids can also be used to study phylogenetics because they have their own DNA.