Lysosome

Overview

A Lysosome is a membrane-bound organelle found in most animal cells. They are spherical vesicles that contain hydrolytic enzymes that can break down virtually all kinds of biomolecules. Lysosomes operate at a pH of 4.5 and are therefore acidic.

Function

Lysosomes are involved in various cell processes. They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. The membrane around a lysosome allows the digestive enzymes to work at the 4.5 pH they require. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents. They are created in the Golgi apparatus.

Structure

The lysosome is surrounded by a membrane which keeps the enzymes inside from leaking out into the cell and causing damage. The lumen's pH (~4.5-5.0) is optimal for the enzymes involved in hydrolysis, which require an acidic environment to function.

Biogenesis

Lysosomes are manufactured and budded into the cytoplasm by the Golgi apparatus. The enzymes found in the lysosomes are created in the rough endoplasmic reticulum, which are then sent to the Golgi apparatus.

Clinical significance

Defects in lysosomal enzyme synthesis can lead to a variety of lysosomal storage disorders that result in an accumulation of specific substrates. These genetic disorders include Tay-Sachs disease, Neimann-Pick disease, and Gaucher's disease.

History

The concept of the lysosome was first introduced by the Belgian cytologist Christian de Duve in 1955, although they had been first observed by electron microscopy in plant cells a few years earlier.