lysosome


lysosome
lysosomal, adj.
/luy"seuh sohm'/, n. Cell Biol.
a cell organelle containing enzymes that digest particles and that disintegrate the cell after its death. See diag. under cell.
[1950-55; LYSO- + -SOME3]

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Membrane-enclosed organelle found in all eukaryotic cells (see eukaryote) that is responsible for the cell's digestion of macromolecules, old cell parts, and microorganisms.

Lysosomes contain a wide variety of enzymes that break down macromolecules such as nucleic acids, proteins, and polysaccharides. Many of the products of lysosomal digestion, including amino acids and nucleotides, are recycled back to the cell for use in synthesizing new cellular components.

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 subcellular organelle that is found in all eukaryotic cells and is responsible for the cell's digestion of macromolecules, old cell parts, and microorganisms. Each lysosome is surrounded by a membrane that maintains an acidic environment within the interior via a proton pump. Lysosomes contain a wide variety of hydrolytic enzymes (acid hydrolases) that break down macromolecules such as nucleic acids, proteins, and polysaccharides. These enzymes are active only in the lysosome's acidic interior; their acid-dependent activity protects the cell from self-degradation in case of lysosomal leakage or rupture, since the pH of the cell is neutral to slightly alkaline. Lysosomes were discovered by the Belgian cytologist Christian René de Duve (Duve, Christian René de) in the 1950s.

      Lysosomes originate by budding off from the membrane of the trans-Golgi network, a region of the Golgi complex responsible for sorting newly synthesized proteins, which may be designated for use in lysosomes, endosomes, or the plasma membrane. The lysosomes then fuse with membrane vesicles that derive from one of three pathways: endocytosis, autophagocytosis, and phagocytosis. In endocytosis, extracellular macromolecules are taken up into the cell to form membrane-bound vesicles called endosomes that fuse with lysosomes. Autophagocytosis is the process by which old organelles are removed from a cell; they are enveloped by internal membranes that then fuse with lysosomes. phagocytosis is carried out by specialized cells (e.g., macrophages) that engulf large extracellular particles such as dead cells or foreign invaders (e.g., bacteria) and target them for lysosomal degradation. Many of the products of lysosomal digestion, such as amino acids and nucleotides, are recycled back to the cell for use in the synthesis of new cellular components.

      Lysosomal storage diseases are genetic disorders in which a genetic mutation affects the activity of one or more of the acid hydrolases. In such diseases, the normal metabolism of specific macromolecules is blocked and the macromolecules accumulate inside the lysosomes, causing severe physiological damage or deformity. Hurler's syndrome, which involves a defect in the metabolism of mucopolysaccharides, is a lysosomal storage disease.

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Universalium. 2010.

Look at other dictionaries:

  • lysosome — [ lizozom ] n. m. • 1968; du gr. lusis (cf. lyse) et sôma « corps » ♦ Biol. Vésicule cytoplasmique des eucaryotes contenant un grand nombre d enzymes qui dégradent la plupart des macromolécules biologiques. Adj. LYSOSOMIAL, IALE, IAUX . ●… …   Encyclopédie Universelle

  • lysosome — lysosome. См. лизосома. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • lysosome — 1955, from LYSO (Cf. lyso ) + some, from Gk. soma body …   Etymology dictionary

  • lysosome — [lī′sə sōm΄] n. [lyso , pertaining to dissolving < Gr lysis (see LYSIS) + SOME3] a particle in the cytoplasm of cells containing a number of digestive enzymes capable of breaking down most of the constituents of living matter: see CELL… …   English World dictionary

  • Lysosome — Les principaux organites d une cellule. Les lysosomes sont légendés en haut à gauche …   Wikipédia en Français

  • Lysosome — s: (1) nucleolus (2) nucleus (3) ribosomes (little dots) (4) vesicle (5) rough endoplasmic reticulum (ER) (6) Golgi apparatus (7) Cytoskeleton (8) smooth endoplasmic reticulum (9) mitochondria (10) vacuole (11) cytoplasm (12) lysosome (13)… …   Wikipedia

  • Lysosome — An organelle (a little organ) within a cell containing enzymes that degrade macromolecules (large molecules) and other materials (such as bacteria) taken up by a cell during the process of endocytosis. In endocytosis, macromolecules and particles …   Medical dictionary

  • lysosome — noun Etymology: International Scientific Vocabulary lys + 3 some Date: 1955 a saclike cellular organelle that contains various hydrolytic enzymes see cell illustration • lysosomal adjective …   New Collegiate Dictionary

  • lysosome — (li so sōm) A spherical membranous eucaryotic organelle that contains hydrolytic enzymes and is responsible for the intracellular digestion of substances …   Dictionary of microbiology

  • lysosome — Membrane bounded cytoplasmic organelle containing a variety of hydrolytic enzymes that can be released into a phagosome or to the exterior. Release of lysosomal enzymes in a dead cell leads to autolysis (and is the reason for hanging game, to… …   Dictionary of molecular biology


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