Plastids and Its Types
For: Science Class 11
Plastids
Plastids are photosynthetic pigments containing bodies found in the cytoplasm of plant cell. There are three types of plastids.
Chloroplasts
Plastids, which contain green colored photosynthetic pigments, are called chloroplast. It is double membraned. A kind of fluid is enclosed by membrane is called stroma. In the stroma number of sac like membranes found called thyllakoid or lamellae. The group of thyllakoid is called granum. The thyllakoid that connects one granum to another granum is called fret. The stroma also caontains DNA RNA and other organic and inorganic substances.
Function of chloroplast
The main function of chloroplast is photosynthesis. The green colored pigments, the chlorophylls traps solar energy and the energy is then converted into chemical energy C6H12O6 with the combination of CO2 and H2O. It is also carrier of genetic materials, as it possesses its own DNA.
Chromoplast
- The plastid, which contains colored photosynthetic pigment other than green, is called chromoplast.
- Yellow coloured pigments are called Xanthophylls.
- Orange colored pigments is called Carotenes
- Red colored pigments are called Erythrocyanine and
- blue colored pigments are called Phycocyanine.
The chromoplasts are also doubling membrane. In the stroma grana are absent and the thyllakoids are found degenerating. They are present in colored parts of the plant body. Their main function is to make colorful the body parts like colorful parts of the flower attracts insects.
Leucoplast
The plastids which contain colorless pigments are called leucoplast. It is doubling membrane. The grana are absent. Developing thyllakoids are present in the stroma. In presence of light the leucoplast changes into chloroplast.
The main function of the leucoplast is to store food materials. It is present in the stem and root. The leucoplast which store starch is called amyloplast, which stores oil, is called elaioplast and which stores protein called aleuroplast.
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Biology