Microbodies: Meaning and Definition of Microbodies, Structure of a Microbody

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Meaning of Microbodies

  • A microbody can be defined as a type of organelle that is found in the cells of plants, protozoa, and animals.

  • An organelle is a specialized subunit in cell biology usually within a cell that has a specific function.

  • Organelles include peroxisomes, glyoxysomes, Glycosome and hydrogenosomes.

  • Microbodies are especially prevalent in the liver and kidney in case of vertebrates.

Structure of Microbodies

  • These bodies are present in the cytosol of the cell called as cytostomes.

  • It has a spherical shape ranging from 0.2-1.5 micrometers in terms of diameter.

  • Microbodies are visible in the cytoplasm of a cell only through an electron microscope.

  • They are surrounded by a single phospholipid bilayer membrane containing a matrix of intracellular material including enzymes and other proteins.

  • They do not seem to contain any genetic material to allow them to self-replicate.

Microbody Structure - A Peroxisome

Microbody Structure - a Peroxisome

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Functions of Microbodies

  • They contain enzymes that participate in the preparatory or intermediate stages of biochemical reactions within the cell.

  • The breakdown of fats, alcohols and amino acids is facilitated.

  • These microbodies are also involved in detoxification of peroxides and in photo respiration in plants.

Peroxisomes

  • It helps the body break down large molecules and detoxify hazardous substances.

  • Enzymes like oxidase, react hydrogen peroxide as a by-product of its enzymatic reactions.

  • Hydrogen peroxide can then be converted to water by enzymes like catalase and peroxidase within the peroxisome.

  • This was discovered and named by C.de Duve.

Glyoxysomes

  • These are specialized peroxisomes found in plants and mold.

  • Stored lipids can be converted into carbohydrates so that they can be used for plant growth.

  • The fatty acids are hydrolyzed to acetyl-CoA by peroxisomal β-oxidation enzymes.

  • Glyoxysomes also possess the key enzymes of the Glyoxylate cycle.

The Glyoxylate Cycle

  • It is a variation of the tricarboxylic acid cycle, is an anabolic pathway occurring in plants, bacteria, protists, and fungi.

  • This cycle enters on the conversion of acetyl-CoA to succinate for the synthesis of carbohydrates.

  • In Plants the glyoxylate cycle occurs in special peroxisomes which are called glyoxysomes.

    • This cycle allows seeds to use lipids as a source of energy.

  • In pathogenic fungi the glyoxylate cycle may serve an entirely different purpose in some species.

  • In some vertebrates some studies show evidence of components of the glyoxylate cycle existing in significant amounts for e.g. in the liver tissue of chickens.

  • Enzymes of the glyoxylate cycle are current inhibition targets for the treatment of diseases due to the central role of the glyoxylate cycle in the metabolism of pathogenic species including fungi and bacteria.

The Glyoxylate cycle

The Glyoxylate Cycle

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Glycosome

  • It is a membrane-enclosed organelle that contains the glycolytic enzymes.

  • It is found in a few species of protozoa including the Kinetoplastida.

  • Kinetoplastida is a group of flagellated protists belonging to the phylum Euglenozoa.

  • At present the Glycosome is being researched as a target for drug therapies.

  • They perform many processes in the cell.

  • The processes include glycolysis, purine salvage, beta oxidation of fatty acids and ether lipid synthesis.

Hydrogenosome

  • It is a membrane-enclosed organelle of some anaerobic ciliates, trichomonads, fungi, and animals.

  • By the combined actions of pyruvate: ferredoxin oxide-reductase, hydrogenase, acetate: succinate CoA transferase and succinate thiokinase, molecular hydrogen, acetate, carbon dioxide and ATP are produced.

  • Hydrogenosome releases molecular hydrogen (H2) as a by-product of energy generation under anaerobic (oxygen-deficient) conditions.

Functions of Microbodies: Hydrogenosome

Functions of Microbodies: Hydrogenosome

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FAQs

Q. What is a microbody?

Answer:

A microbody can be defined as a type of organelle that is found in the cells of plants, protozoa, and animals.

Q. What are the three main parts in the structure of microbodies?

Answer:

The three main parts in the structure of microbodies are:

i) Crystalline Core

ii) Lipid Bilayer

iii) Plasma Membrane