Peroxisome Function and Structure

Peroxisomes, also termed as microbodies, are organelles found in all eukaryotic cells. The peroxisome function is mostly involved in the catabolism of branched and very long fatty acids. This organelle is a specialized structure that aids in getting rid of the host organism of toxins in the body. Peroxisomes in animals are often especially concentrated in the vicinity of kidneys and liver, which are known as the body’s filtration centers for toxins. Peroxisomes in plants assist with photosynthesis. A disorder in this organelle can be a critical problem; as such structures are crucial to the wellbeing of most life on Earth.

Like the other cell’s specialized structures, peroxisomes are surrounded by proteins and lipids that protects the rest of the cell from the activity done inside it. They are roughly spherical in shape and conduct almost the same function as other organs do, but only on a much smaller scale. Peroxisomes are first firmly identified in 1967, which is a decade after they had been defined by a Swedish doctoral student. They are known to be a rather unique organelle due to its capability of replicating itself, much like DNA. The existing peroxisomes can grow and split themselves when more of them are needed in a cell.

Peroxisome Structure

Peroxisomes are the same size as the lysosomes, which are around 0.5 to 1.5 micrometers. The peroxisome structure is similar to lysosomes because they are filled with enzymes and are enclosed by a single membrane. However, lysosomes bud off from the Golgi apparatus unlike peroxisomes that comes from the endoplasmic reticulum. The proteins and enzymes destined for peroxisomes are synthesized in the cytosol. Each contains a peroxisomal targeting signal (PTS) that binds to a receptor molecule that takes the protein into the peroxisome and then returns for another load.

There are two identified peroxisomal targeting signals which are: a tripeptide at the C-terminal and a 9-amino acid sequence at the N-terminal of the protein. Each PTS has its own receptor to lead it to the peroxisome.

The functions of peroxisome in the human liver include breaking down (by oxidation) of excess fatty acids; participates in the synthesize of cholesterol; breaking down of hydrogen peroxide; breaking down of excess purines such as GMP and AMP to uric acid; and participates in the synthesize of the lipids used in making myelin. This organelle is also present in plant cells that have functions as photorespiration and symbiotic nitrogen fixation.

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