Lysosomes Research Paper

552 Words 3 Pages
Describe the structure and function of a lysosome.
Lysosomes are a cell organelle, translating as an independent structure within a cell, possessing a specific structure and function. For a lysosome its functions include; digestion of intracellular or extracellular material, nutrition from digested macromolecules and defence/protection from harmful substances. Lysosomes are variable from cell to cell in terms of shape and size but are conventionally spherical or oval shaped, 0.5µm in diameter and around 0.5-5µm in length.
The internal lumen of a lysosome contains enzymes that catabolically break down biological macromolecules via hydrolysis reactions (insertion of a water molecule that breaks intramolecular bonds). Enzymes include; proteases, ribonucleases, deoxyribonucleases – all defined as hydrolases. Such enzymes are synthesised at ribosomes found on endoplasmic reticulum, and are packaged into vesicles that bud from the Trans
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Secondary lysosomes digest extracellular material of which is engulfed into the cell by a process called endocytosis. A phagocytic vesicle is pinched off from the cell plasma membrane and encloses the material to be digested. This vesicle fuses with the lysosome to form a phagolysosome complex. The acidic environment denatures macromolecules to increase their surface area for hydrolases to act. Once broken down, the soluble, useful material such as sugars, amino acids and nucleotides are used by the cell as nutrients; they enter the cytosol through the lysosomal membrane by either facilitated diffusion or active transport. Indigestible material remains within the lysosome to form a residual body; this is removed from the cytoplasm by exocytosis and is excreted from the body as metabolic waste. On the other hand an accumulation of residual bodies contributes to cellular

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