Medical research

Researchers solve mystery surrounding a form of Batten disease

A team led by researchers at Baylor College of Medicine has uncovered an unexpected mechanism that can explain a form of Batten disease called neuronal ceroid lipofuscinosis 8. The findings published in the journal Nature ...

Alzheimer's disease & dementia

Alzheimer's linked to the brain's 'garbage disposal service'

Researchers in South Australia have found a genetic link between Alzheimer's disease and the endo-lysosomal system, a critical part of biological recycling machinery that maintains the health of brain cells.

Cancer

Study shows how to make (and destroy) a metastatic cancer cell

Many cancers become especially dangerous only when they metastasize from their site of origin to faraway tissues such as lung, brain or bone. Now, a University of Colorado Cancer Center study published today in the Proceedings ...

Medical research

Simple sugar delays neurodegeneration caused by enzyme deficiency

A new therapeutic approach may one day delay neurodegeneration typical of a disease called mucopolysaccharidoses IIIB (MPS IIIB). Neurodegeneration in this condition results from the abnormal accumulation of essential cellular ...

Genetics

Gene loss can lead to accumulation of waste products in cells

MIT biologists have discovered a function of a gene that is believed to account for up to 40 percent of all familial cases of amyotrophic lateral sclerosis (ALS). Studies of ALS patients have shown that an abnormally expanded ...

Parkinson's & Movement disorders

Mechanism behind common Parkinson's mutation discovered

Northwestern Medicine investigators have discovered how a gene mutation results in buildup of a toxic compound known to cause Parkinson's disease symptoms, defining for the first time the mechanism underlying that aspect ...

Medical research

Study reveals key molecular link in major cell growth pathway

A team of scientists led by Whitehead Institute has uncovered a surprising molecular link that connects how cells regulate growth with how they sense and make available the nutrients required for growth. Their work, which ...

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Lysosome

Lysosomes are cellular organelles that contain acid hydrolase enzymes to break down waste materials and cellular debris. They are found in animal cells, while in yeast and plants the same roles are performed by lytic vacuoles. Lysosomes digest excess or worn-out organelles, food particles, and engulf viruses or bacteria. The membrane around a lysosome allows the digestive enzymes to work at the 4.5 pH they require. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents. They are created by the addition of hydrolytic enzymes to early endosomes from the Golgi apparatus. The name lysosome derives from the Greek words lysis, to separate, and soma, 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 the 1960s.

The size of lysosomes varies from 0.1–1.2 μm. At pH 4.8, the interior of the lysosomes is acidic compared to the slightly alkaline cytosol (pH 7.2). The lysosome maintains this pH differential by pumping protons (H+ ions) from the cytosol across the membrane via proton pumps and chloride ion channels. The lysosomal membrane protects the cytosol, and therefore the rest of the cell, from the degradative enzymes within the lysosome. The cell is additionally protected from any lysosomal acid hydrolases that drain into the cytosol, as these enzymes aren't pH-sensitive and function as well in the alkaline environment of the cytosol.

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