Alzheimer's disease & dementia

An alternate theory for what causes Alzheimer's disease

Alzheimer's disease, the most common cause of dementia among the elderly, is characterized by plaques and tangles in the brain, with most efforts at finding a cure focused on these abnormal structures. But a University of ...

Genetics

Surprising pathway implicated in stuttering

Researchers at Washington University School of Medicine in St. Louis have obtained new evidence that at least some persistent stuttering is caused by mutations in a gene governing not speech, but a metabolic pathway involved ...

Medical research

Scientists use blood-brain barrier as therapy delivery system

The blood brain barrier is generally considered an obstacle to delivering therapies from the bloodstream to the brain. However, University of Iowa researchers have discovered a way to turn the blood vessels surrounding brain ...

Oncology & 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 ...

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 ...

Parkinson's & Movement disorders

Linking Gaucher and Parkinson's Diseases

Gaucher (pronounced "go-shay") disease affects one in 450 Jewish people of Ashkenazi (eastern European) descent (one in 10 is a carrier), yet only 1 in 40,000 people in the general population. Of course mutations can happen ...

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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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