The tiny, granular, self-reproducing and enzyme-rich organelles surrounded by a membrane are called peroxisomes. They are also called microsomes. Its diameter is 0.2-17 millimicrons. It contains enzymes in crystal and granule form. At its center, fine-grained material accumulates to form an opaque core. It is called nucleoid. Its main enzymes are catalase, D-amino acid oxidase and uric acid oxidase. It breaks down fatty acids into acetyl Co by beta-oxidation process. Organelles that carry out beta-oxidation are called glyoxysomes. Belgian psychologist Christian de Duve discovered it in 1967.
Peroxisomes are abundant in photosynthetic cells of plants, such as those in the embryo membrane, liver and kidney cells. Peroxisomes arise from rough endoplasmic reticulum.
Function/importance of peroxisomes
- It breaks down fatty acids into acetyl Co by beta-oxidation process.
- Enzymes present in it react H2 and O2 to produce toxic H2O2.
- Catalase enzyme breaks down toxic H2O2 to produce water and oxygen.
- Catalase enzyme uses H2O2 to oxidize alcohol, phenol, formic acid, formaldehyde etc.
- It destroys blood toxins in human liver and kidney by causing peroxidation reaction.
- Plant cells contain a large number of antioxidative enzymes (superoxide dismutase, NADP dehydrogenase) that catalyze important reactions.
- It regulates the concentration of oxygen in the cells.
- It helps in the production of NAD, DNA and RNA.
- It turns love into water.
- It helps in making glycine and serine in plant cells.
- It helps carry out photosynthesis in green plants.