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Cell Structure and Cell Organelles

Cytoplasmic Vesicles: Lysosomes und Peroxisomes

Lysosomesare morphologically heterogeneous, cytoplasmic particles enclosed by a single membrane. They are found in both animal and plant cells. They are characterized by their content of hydrolytic enzymes. Their function depends strongly on the types of enzymes within, but is only initiated through hormone- or metabolism-controlled disintegration of the membrane and release of the enzyme load. Lysosomes can be considered to be the waste-removal systems of the cell. They break down or degrade substances that enter the cell (through pino-, endo-, or phagocytosis). Lysosomes can also dispose of spent cell organelles.

Peroxisomes are microbodies that are also found in animal, plant, fungal, and protozoan cells. They contain peroxidase, catalase and related enzymes. Although they resemble lysosomes, they have a completely different origin because they are not produced by the Golgi apparatus. They are normally characterized by the crystalline structure of their core; however, they are not related to storage granules. Peroxisomes neutralize and remove toxic substances such as hydrogen peroxide and are thus particularly abundant in liver tissue.

Fig.1
Lysosomes

Small membrane-bound organelles in eukaryotes. Made by the Golgi apparatus. Contain hydrolytic enzymes: proteases, nucleases, lipases, and phosphatases. Primary function: enzymatic digestion of absorbed foreign substances.

3D Animations: Phagocytosis and Endocytosis

Links and Literature

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