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A lysosome (/ ˈ l aɪ s ə ˌ s oʊ m /) is a single membrane-bound organelle found in many animal cells. [1] [2] They are spherical vesicles that contain hydrolytic enzymes that digest many kinds of biomolecules. A lysosome has a specific composition, of both its membrane proteins and its lumenal proteins.
The process of creating vesicles within the endosome is thought to be enhanced by the peculiar lipid BMP or LBPA, which is only found in late endosomes, endolysosomes or lysosomes. [12] When the endosome has matured into a late endosome/MVB and fuses with a lysosome, the vesicles in the lumen are delivered to the lysosome lumen.
Through this process, sugars, amino acids, and other monomers pass into the cytosol and become nutrients for the cell. Lysosomes also use their hydrolytic enzymes to recycle the cell's obsolete organelles in a process called autophagy. The lysosome engulfs another organelle and uses its enzymes to take apart the ingested material.
Both organelles, the mitochondria and chloroplasts (in photosynthetic organisms), are compartments that are believed to be of endosymbiotic origin. Other compartments such as peroxisomes, lysosomes, the endoplasmic reticulum, the cell nucleus or the Golgi apparatus are not of endosymbiotic origin.
Mitochondria: Commonly known as the powerhouse of the cell is a double membrane bound cell organelle. [19] This functions for the production of energy or ATP within the cell. Specifically, this is the place where the Krebs cycle or TCA cycle for the production of NADH and FADH occurs.
Lysosomes and peroxisomes: Lysosomes contain digestive enzymes (acid hydrolases). They digest excess or worn-out organelles , food particles, and engulfed viruses or bacteria . Peroxisomes have enzymes that rid the cell of toxic peroxides , Lysosomes are optimally active in an acidic environment.
The process of phagocytosis showing phagolysosome formation. Lysosome(shown in green) fuses with phagosome to form a phagolysosome. Membrane fusion of the phagosome and lysosome is regulated by the Rab5 protein, [1] a G protein that allows the exchange of material between these two organelles but prevents complete fusion of their membranes. [1]
Prokaryotes have fewer organelles than eukaryotes. Both have plasma membranes and ribosomes (structures that synthesize proteins [ clarification needed ] and float free in cytoplasm ). Two unique characteristics of prokaryotes are fimbriae (finger-like projections on the surface of a cell) and flagella (threadlike structures that aid movement).