Microbodies

Peroxisomes and glyoxysomes are microbodies formed from ER which superficially resemble the lysosomes. Peroxisomes are spherical bodies limited by a single membrane. The centre of peroxisomes is occupied by a fine granular core called 'nucleoid'.

Peroxisomes contain oxidising enzymes which are synthesised by ribosomes. These enzymes are uric acid oxidase, D-amino acid oxidase, hydroxyl acid oxidase which produce hydrogen peroxide on oxidation, while peroxisomal catalase, the enzyme found in lysosomes, destroys hydrogen peroxide. Since hydrogen peroxide is toxic to the cell, catalase plays a protective role by breaking down hydrogen peroxide. Hence, peroxisomes play an important role in detoxification. In green plants, peroxisomes carry out a process called photorespiration.

Glyoxysomes are a form of peroxisome which contain enzymes like isocitrate lyase. and malate synthetase which are specific to gloxylate cycle. They also have several Krebs cycle enzymes about which you will study later. Glyoxysomes are the essential components of plant cell.