Lysosomes & Peroxisomes

Lysosomes: Lysosomes    are  vesicular organelles that form by breaking off from the Golgi apparatus and then dispersing throughout the cytoplasm. The lysosomes  provide an intracellular digestive system that allows the cell to digest:

 (1) Damaged cellular structures.

 (2) Food particles that have been  ingested by the cell.

 (3) Unwanted matter such as bacteria.

It is surrounded by a typical lipid bilayer membrane and is filled with large numbers of small granules, which are  protein aggregates of as many as 40 different hydrolase (digestive) enzymes. A hydrolytic enzyme is capable of splitting an organic compound into two or  more parts.

Peroxisomes:    Peroxisomes are similar physically to lysosomes, but they are different in two important ways:

 First, they are  believed to be formed by self-replication (or perhaps by budding off  from the smooth endoplasmic reticulum) rather than from the Golgi apparatus.

 Second, they contain  oxidases  rather than hydrolases. Several  of the oxidases are capable of combining oxygen with hydrogen ions derived from different intracellular chemicals to form hydrogen peroxide (H2O2). Hydrogen  peroxide is a highly oxidizing substance and is used in  association with catalase, another oxidase  enzyme present in large quantities in peroxisomes, to  oxidize many substances that might otherwise be poisonous  to the cell.