Lysosomes and Lysosomal Disorders
Lysosomes are membranous vesicles that are present in almost all kinds of body cells. Their number varies greatly from one cell to another, depending on its type and function. They have been given their name because they are small bodies (soma = body) containing various enzymes that are hydrolytic (lysis = dissolution). These hydrolytic enzymes, hydrolases, catalyze reactions in which large molecules are broken down into smaller components. The diameter of lysosomes is about 0.5 µm. Lysosomes contain many hydrolytic enzymes, including acid phosphatase, the one most easily tested for by a histochemical technique. Its demonstration in a membranous organelle is usually taken as proof that the organelle is a lysosome. Lysosomes contain proteases, nucleases, glycosidases, lipases, phospholipases, certain sulfatases, and phosphatases — all hydrolytic enzymes. These enzymes are capable of lysing the various components of the cytoplasmic matrix. The lysosomal membrane is necessary in order to separate the hydrolytic enzymes from the rest of the cytoplasm. The enzymes of lysosomes are synthesized in the rough-surfaced endoplasmic reticulum. The lysosomal vesicles originate from the Golgi apparatus.
KeywordsStorage Disease Glycogen Storage Disease Lysosomal Storage Disease Metachromatic Leukodystrophy Repeat Disaccharide Unit
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