BIOLOGY FOR ENGINEERS - PEROXISOMES

 Peroxisome 

Peroxisome is membrane-bound organelle occurring in the cytoplasm of eukaryotic cells. ... Peroxisomes contain enzymes that oxidize certain molecules normally found in the cell, notably fatty acids and amino acids. Those oxidation reactions produce hydrogen peroxide, which is the basis of the name peroxisome.

Typical Animal cell and plant cell

Animal cell : 

 

Plant cell: 

Introduction : 

Peroxisomes were described in 1960 as part of the pioneering work of Christian René de Duve, who developed cell fractionation techniques. De Duve’s method separated organelles on the basis of their sedimentation and density properties, and peroxisomes are denser than other organelles. He later coined the term peroxisome. De Duve shared the 1974 Nobel Prize for Physiology or Medicine with Albert Claude and George Palade for that work.

Functions of peroxisomes :

In animal cell : 

Peroxisomes, sometimes called microbodies are generally small (about 0.1 – 1.0 µm in diameter) organelles found in animal and plant cells. ... Peroxisomes break down organic molecules by the process of oxidation to produce hydrogen peroxide. This is then quickly converted to oxygen and water.

In enzymes : 

Peroxisomes are found in all eucaryotic cells. They contain oxidative enzymes, such as catalase and urate oxidase, at such high concentrations that in some cells the peroxisomes stand out in electron micrographs because of the presence of a crystalloid core. 

In a cell : 

Peroxisomes are organelles that sequester diverse oxidative reactions and play important roles in metabolism, reactive oxygen species detoxification, and signaling. Oxidative pathways housed in peroxisomes include fatty acid β-oxidation, which contributes to embryogenesis, seedling growth, and stomatal opening.

Structure of peroxisome :

These are made of a phospholipid bilayer with many membrane-bound proteins. ... Due to the ingress of proteins and lipids, the peroxisome grows in size and divides into two organelles. Peroxisomes do not have their own DNA. Proteins are transported from the cytosol after translation.

Important points about peroxisomes : 

• Peroxisomes are indispensable for human health and  development. They represent ubiquitous subcellular organelles which compartmentalize enzymes responsible for several crucial metabolic processes such as β-oxidation of specific fatty acids, biosynthesis of ether phospholipids and metabolism of reactive oxygen species. 

• Lipid metabolism and chemical detoxification are important functions of peroxisomes. Peroxisomes are responsible for oxidation reactions that break down fatty acids and amino acids. Peroxisomes oversee reactions that neutralize free radicals, which cause cellular damage and cell death.

•Peroxisomes contain a variety of enzymes, which primarily function together to rid the cell of toxic substances, and in particular, hydrogen peroxide (a common byproduct of cellular metabolism).

•Peroxisomes are organelles that sequester diverse oxidative reactions and play important roles in metabolism, reactive oxygen species detoxification, and signaling. Oxidative pathways housed in peroxisomes include fatty acid β-oxidation, which contributes to embryogenesis, seedling growth, and stomatal opening.

•Peroxisomes are small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions, including several aspects of energy metabolism.

•peroxisomes are mostly found in liver and kidney cells because the peroxisomes are specialized for carrying out some oxidative reaction, such as detoxification or remove toxic substance from the cell.

What happens if peroxisome is not present? 

A peroxisome protein is involved in preventing one cause of kidney stones. In plants a type of peroxisome converts fatty acids to carbohydrates. Several rare inherited malfunctions of peroxisomes can lead to death.