Microbodies

Introduction

Microbodies are the subcellular single-membrane organelles that absorb oxygen and oxidize. Rhodin, a biologist, reported it in 1954 in the proximal convoluted tubule of a mouse. However, Porter and Caulfield reported microbodies in plant cells in 1958. These cytosomes are present in eukaryotic organisms. It was earlier considered the subcellular organelle, but later scientists evaluated its importance. These cytoplasmic organelles are like a vesicle and can be globular or spherical. Invertebrates are most prevalent in the liver and kidneys. They are present in cytosol, therefore, called cytosomes. These can only be visible through the electron microscope. They consist of degradative enzymes which are enveloped in a single membrane. They act as the containers of every metabolic activity in plants and animals.

Structure of Microbodies

Microbodies of cytosomes are extremely small in size ranging from 0.2 to 1.5 μm. They are present in the cytoplasm of the cells. Each microbody resembles a vesicle and is spherical. A single phospholipid bilayer membrane surrounds them and they consist of an intracellular matrix of proteins and enzymes. These enzymes take part in various chemical and metabolic reactions occurring inside the animal and plant bodies. For instance, these enzymes facilitate the breakdown of fats, alcohol and amino acids. However, they lack genetic materials like DNA and RNA and cannot self-replicate.

Microbodies – Functions

In microbodies, functions depend upon their type. Some of the basic microbodies functions are as follows:

• They act as enzymes in various biochemical reactions
• They are responsible for oxidative reactions by using molecular oxygen
• They do a breakdown of fats, amino acids and alcohol
• They are also necessary for the process of glycolysis and photorespiration in plants
• They play an essential role in reactive oxygen species detoxification
• They also act as the site for glyoxylate cycles occurring in plants

Types of Microbodies

The classification of cytosomes depends upon their functions. The types of microbodies are as follows:

Peroxisomes

-Peroxisomes are the cytosomes present in the entire eukaryotic organism

-They are single-membraned structures where the membrane acts as the separating layer between the enzymes and cytosol

-They are responsible for the oxidation of fatty acids. As a result of oxidation, hydrogen peroxide(H2O2) gas liberates, due to which it got its name as peroxisomes

-The catalase enzyme of peroxisome converts this hydrogen peroxide to water and oxygen, as the hydrogen peroxide gas is very toxic. Thus, peroxisomes are also responsible for removing toxicants peroxides from the cells

-In plants, peroxisomes occurs in cells of green tissues and concerned with photorespiration (glycolate pathway) 

Glyoxysomes

-Glyoxysomes are specialized peroxisomes present in plants and fungi(yeast cells and  guard cells of plant) , specifically in the fat-storing tissues of germinating seed

-Glyoxysomes occus  in plants especially in fatty seeds  (castor seed) , guard cells of stomata and bunripe fruits. Glyoxylate cycle is linked with the TCA cycle and used for production of acids in fruit

-Glyoxysomes are considered as a highly specialised peroxisomes. Glyoxylic acid cycle takeds place in glyoxysomes . The cycle convert fats into carbohydrats

Glycosomes

-Glycosomes are organelles that contain glycolytic enzymes

-They discovered that the cell’s glycogen was dynamic instead of static

-It is present in the species of protozoa in the cytoplasm

-It consists of glycogen and protein units

 The shape varies from round to oval depending upon the species

– They are often attached to other organelles such as rough endoplasmic reticulum, mitochondria, sarcolemma and Golgi apparatus

– It contains all the enzymes which are necessary for glycolysis, glycerol metabolism and fixation of CO2

-Glycosomes are also responsible for purine salvage

The Glycosomes are further divided into two categories:

• Lycoglycosomes: Lycoglycosomes are the free glycosomes present within the cytosol. They are highly affected by the action of acids. It is possible to extract Lycoglycosomes from the boiling water
• Desmos Glycosomes: Desmoglycosomes are confined to other cell organelles and are not present freely. They are not affected by the action of acids. It is not possible to extract desmoglycosomes from the boiling water as they are bound with tissues

Woronin bodies

Woronin bodies are also the derivative of peroxisomes. They were named after the Russian botanist Mikhail Stepanovich Woronin. They are dense core microbodies protected by double-layered membranes. The main component of Woronin bodies is the peroxisomal protein Hex1. They are present in the filamentous Ascomycota near the septae dividing hyphal compartments. The function is to seal the septal pore due to cellular damage or hyphal wounding. Thus, it prevents the excess loss of cytoplasm. The size of it varies from 100 nm to around 1 μm. They are microscopic units.

Conclusion

Microbodies are tiny single-membrane organelles responsible for the oxidation and breakdown of biomolecules. As they are present in cytosol, therefore also called cytosomes. Their primary function is to break down fats, alcohol and amino acids. They play a vital role in various metabolic reactions such as glycolysis, photorespiration and the glyoxylate cycle.