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Encyclopedia > Lysosome
Various organelles labeled. The lysosome is labeled in the upper left.
Various organelles labeled. The lysosome is labeled in the upper left.
Schematic of typical animal cell, showing subcellular components. Organelles: (1) nucleolus (2) nucleus (3) ribosome (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) centrioles
Schematic of typical animal cell, showing subcellular components. Organelles: (1) nucleolus (2) nucleus (3) ribosome (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) centrioles


Lysosomes are organelles that contains digestive enzymes (acid hydrolases). They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria. The membrane surrounding a lysosome prevents the digestive enzymes inside from destroying the cell. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents. They are built in the Golgi apparatus. The name lysosome derives from the Greek words lysis, which means dissolution or destruction, and soma, which means body. They are frequently nicknamed "suicide-bags" or "suicide-sacs" by cell biologists due to their role in autolysis. Lysosomes were discovered by the Belgian cytologist Christian de Duve in 1949. Image File history File links Illu_cell_structure. ... Image File history File links Illu_cell_structure. ... In cell biology, an organelle is one of several structures with specialized functions, suspended in the cytoplasm of a eukaryotic cell. ... Image File history File links Biological_cell. ... Image File history File links Biological_cell. ... Schematic of typical animal cell, showing subcellular components. ... The nucleolus is contained within the cell nucleus. ... HeLa cells stained for DNA with the Blue Hoechst dye. ... Figure 1: Ribosome structure indicating small subunit (A) and large subunit (B). ... In cell biology, a vesicle is a relatively small and enclosed compartment, separated from the cytosol by at least one lipid bilayer. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... The eukaryotic cytoskeleton. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... Electron micrograph of a mitochondrion showing its mitochondrial matrix and membranes In cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed organelle that is found in most eukaryotic cells. ... Schematic of typical animal cell, showing subcellular components. ... Organelles. ... A centriole showing the nine triplets of microtubules. ... Schematic of typical animal cell, showing subcellular components. ... Digestive enzymes are enzymes in the alimentary tract that break down food so that the organism can absorb it. ... In biochemistry, a hydrolase is an enzyme that can break a chemical bond by hydrolysis. ... Schematic of typical animal cell, showing subcellular components. ... This article is about biological infectious particles. ... Phyla Actinobacteria Aquificae Chlamydiae Bacteroidetes/Chlorobi Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Lentisphaerae Nitrospirae Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Verrucomicrobia Bacteria (singular: bacterium) are unicellular microorganisms. ... A biological membrane or biomembrane is an enclosing or separating tissue which acts as a barrier within or around a cell. ... Digestive enzymes are enzymes in the alimentary tract that break down food so that the organism can absorb it. ... Schematic of typical animal cell, showing subcellular components. ... Schematic of typical animal cell, showing subcellular components. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ... In chemistry, autolysis is the production of a substance which catalyses the reaction it was made in, or catalyzes its own transformation into another compound. ... Christian de Duve (born October 2, 1917) is a biochemist. ...

Contents

Acidic environment

At pH 4.8, the interior of the lysosomes is more acidic than the cytosol (pH 7.2). The lysosome's single membrane stabilizes the low pH by pumping in protons (H+) from the cytosol via proton pumps and chloride ion channels. The membrane also protects the cytosol, and therefore the rest of the cell, from the degradative enzymes within the lysosome. For this reason, should a lysosome's acid hydrolases leak into the cytosol, their potential to damage the cell will be reduced, because they will not be at their optimum pH. Lysosomes are the garbage disposal of the cell and they are made by the golgi apparatus. For other uses, see PH (disambiguation). ... The cytosol (cf. ... Look up cell membrane in Wiktionary, the free dictionary. ... For other uses, see Proton (disambiguation). ... proton gradient: Pink represents the matrix while the red dots represent protons. ... Ion channels are pore-forming proteins that help to establish and control the small voltage gradient that exists across the plasma membrane of all living cells (see cell potential) by allowing the flow of ions down their electrochemical gradient. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell being used to describe the smallest unit of a living organism Cells in culture, stained for keratin (red) and DNA (green) The cell is the... penis wenis no one cares ... Wikipedia does not yet have an article with this exact name. ... Micrograph of Golgi apparatus, visible as a stack of semicircular black rings near the bottom. ...


Enzymes

Some important enzymes in these are:

Lysosomal enzymes are synthesized in the cytosol and the endoplasmic reticulum, where they receive a mannose-6-phosphate tag that targets them for the lysosome. Aberrant lysosomal targeting causes inclusion-cell disease, whereby enzymes do not properly reach the lysosome, resulting in accumulation of waste within these organelles. A computer-generated image of a type of pancreatic lipase (PLRP2) from the guinea pig. ... Some common lipids. ... Carbohydrase is a group of enzymes (as amylase) that promote hydrolysis or synthesis of a carbohydrate (as a disaccharide). ... Lactose is a disaccharide found in milk. ... Proteases (proteinases, peptidases, or proteolytic enzymes) are enzymes that break peptide bonds between amino acids of proteins. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... A nuclease is an enzyme capable of cleaving the phosphodiester bonds between the nucleotide subunits of nucleic acids. ... Look up nucleic acid in Wiktionary, the free dictionary. ... A phosphatase is an enzyme that dephosphorylates its substrate; i. ... This article is about orthophosphoric acid. ... The endoplasmic reticulum or ER is an organelle found in all eukaryotic cells that is an interconnected network of tubules, vesicles and cisternae that is responsible for several specialized functions: Protein translation, folding, and transport of proteins to be used in the cell membrane (e. ... D and L forms Haworth projection of mannose in its α-D-mannopyranose form. ... ML II is also referred to as inclusion-cell (I-cell) disease because waste products, thought to include carbohydrates, lipids, and proteins, accumulate into masses known as inclusion bodies. ...


Functions

The lysosomes are used for the digestion of macromolecules from phagocytosis (ingestion of other dying cells or larger extracellular material), endocytosis (where receptor proteins are recycled from the cell surface), and autophagy (where old or unneeded organelles or proteins, or microbes which have invaded the cytoplasm are delivered to the lysosome). Autophagy may also lead to autophagic cell death, a form of programmed self-destruction, or autolysis, of the cell, which means that the cell is digesting itself. Illustration of a polypeptide macromolecule The term macromolecule by definition implies large molecule. In the context of biochemistry, the term may be applied to the four conventional biopolymers (nucleotides, proteins, carbohydrates, and lipids), as well as non-polymeric molecules with large molecular mass such as macrocycles. ... Steps of a macrophage ingesting a pathogen: a. ... Endocytosis (IPA: ) is a process whereby cells absorb material (molecules such as proteins) from the outside by engulfing it with their cell membrane. ... In biochemistry, a receptor is a protein on the cell membrane or within the cytoplasm or cell nucleus that binds to a specific molecule (a ligand), such as a neurotransmitter, hormone, or other substance, and initiates the cellular response to the ligand. ... Autophagy is also a synonym for self-cannibalism Autophagy, or ocytosis, is a process of sequestering organelles and long-lived proteins in a double-membrane vesicle inside the cell, where the contents are subsequently delivered to the lysosome for degradation. ... Autophagy is also a synonym for self-cannibalism Autophagy, or ocytosis, is a process of sequestering organelles and long-lived proteins in a double-membrane vesicle inside the cell, where the contents are subsequently delivered to the lysosome for degradation. ... Programmed cell death (PCD) is the deliberate suicide of an unwanted cell in a multicellular organism. ... In chemistry, autolysis is the production of a substance which catalyses the reaction it was made in, or catalyzes its own transformation into another compound. ...


Other functions include digesting foreign bacteria (or other forms of waste) that invade a cell and helping repair damage to the plasma membrane by serving as a membrane patch, sealing the wound. Lysosomes also do much of the cellular digestion required to digest tails of tadpoles and to remove the web from the fingers of a 3-6 month old fetus. This process of programmed cell death is called apoptosis.[1] Drawing of a cell membrane A component of every biological cell, the cell membrane (or plasma membrane) is a thin and structured bilayer of phospholipid and protein molecules that envelopes the cell. ... A section of mouse liver showing an apoptotic cell indicated by an arrow Apoptosis (pronounced apo tō sis) is a process of suicide by a cell in a multicellular organism. ...


Clinical relevance

There are a number of illnesses that are caused by the malfunction of the lysosomes or one of their digestive proteins, e.g., Tay-Sachs disease, or Pompe's disease. These are caused by a defective or missing digestive protein, which leads to the accumulation of substrates within the cell, impairing metabolism. Tay-Sachs disease (abbreviated TSD, also known as GM2 gangliosidosis, Hexosaminidase A deficiency or Sphingolipidosis) is a genetic disorder, fatal in its most common variant known as Infantile Tay-Sachs disease. ... Pompes disease is a type II glycogen storage disease. ... Structure of the coenzyme adenosine triphosphate, a central intermediate in energy metabolism. ...


Broadly, these can be classified as mucopolysaccharidoses, GM2 gangliosidoses, lipid storage disorders, glycoproteinoses, mucolipidoses, or leukodystrophies. The mucopolysaccharidoses are a group of inherited metabolic diseases caused by the absence or malfunctioning of lysosomal enzymes needed to break down molecules called glycosaminoglycans - long chains of sugar carbohydrates in each of our cells that help build bone, cartilage, tendons, corneas, skin and connective tissue. ... Tay-Sachs disease (abbreviated TSD, also known as GM2 gangliosidosis) is a fatal genetic disorder, inherited in an autosomal recessive pattern, in which harmful quantities of a fatty substance called ganglioside GM2 accumulate in the nerve cells in the brain. ... Lipid storage disorders (or lipidoses) are a group of inherited metabolic disorders in which harmful amounts lipids (fats) accumulate in some of the body’s cells and tissues. ... Glycoproteinosis (or glycoprotein storage disorders) refers to a lysosomal storage disease affecting glycoproteins. ... Mucolipidoses (ML) are a group of inherited metabolic diseases that affect the body’s ability to carry out the normal turnover of various materials within cells. ... Leukodystrophy refers to progressive degeneration of the white matter of the brain due to imperfect growth or development of the myelin sheath, the fatty covering that acts as an insulator around nerve fiber. ...


Additional images

External links

  • 3D structures of proteins associated with lysosome membrane

References

  1. ^ Mader, Sylvia. (2007). Biology 9th ed. McGraw Hill. New York. ISBN 978-0072464634
  • This article contains material from the Science Primer published by the NCBI, which, as a U.S. government publication, is in the public domain.

 
 

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