Lysosome
Say it: LY-suh-sohm
A lysosome is a membrane-bound organelle filled with acidic digestive enzymes that break down worn-out cell parts, food particles and microbes.
Also: lysosomes
Definition
What is a lysosome?
A lysosome is a small organelle that serves as a cell's digestion and recycling compartment. It is best known from animal cells; plant cells do most of the same work in their large central vacuole. A single membrane encloses many kinds of hydrolytic enzymes, which split proteins, nucleic acids, carbohydrates and lipids into their building blocks so the cell can reuse them. The interior is kept much more acidic than the surrounding cytoplasm, and the enzymes work best at that low pH.
Lysosomes fuse with vesicles carrying material brought in from outside, such as bacteria engulfed by a macrophage, and with vesicles wrapped around the cell's own damaged organelles, a recycling process called autophagy. The acidity is also a safeguard: enzymes that leak into the near-neutral cytoplasm are far less active.
When a gene for one lysosomal enzyme is faulty, the substance that enzyme should digest builds up inside lysosomes, causing a lysosomal storage disease such as Tay-Sachs disease. The Belgian biochemist Christian de Duve discovered lysosomes and named them in 1955.
Word parts
Where does the word “lysosome” come from?
- lyso-
- loosening, dissolvingGreek lysis
- -some
- bodyGreek soma
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Terms that go with it
- OrganelleAn organelle is a specialized structure inside a cell, usually wrapped in its own membrane, that carries out a particular job for the cell.
- EndocytosisEndocytosis is how a cell brings material in from outside: its membrane folds inward around the material and pinches off to form a vesicle.
- Golgi apparatusThe Golgi apparatus is a stack of flattened membrane sacs that modifies, sorts and packages proteins and lipids sent from the endoplasmic reticulum.
- EnzymeAn enzyme is a biological catalyst, usually a protein, that speeds up a specific chemical reaction without being used up in the process.
- MacrophageA macrophage is a large white blood cell that engulfs and digests microbes, dead cells and debris, and signals other immune cells to act.
- ApoptosisApoptosis is programmed cell death, a controlled process in which a cell dismantles itself in an orderly way without harming its neighbors.
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Checked against
Written for biofideX in plain words, after checking these references:
- OpenStax Biology 2e, 4.4 The Endomembrane System and Proteins
- NHGRI Talking Glossary: Lysosome
- MeSH (NLM): Lysosomes
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