Alzheimer's disease & dementia

Modified protein can prevent Alzheimer's disease in mice

The amyloid precursor protein has always been vilified as a major cause of Alzheimer's disease. One of its fragments, the amyloid-beta peptide, can break off and accumulate in the brain, giving rise to the puffy white globs ...

Medical research

Exercise may have different effects in the morning and evening

Researchers from the University of Copenhagen have learned that the effect of exercise may differ depending on the time of day it is performed. In mice, they demonstrate that exercise in the morning results in an increased ...

Diseases, Conditions, Syndromes

Clues to building a better herpes vaccine

Efforts to develop an effective vaccine for genital herpes, a common sexually transmitted disease, have largely failed. In a new study published in Nature, Yale researchers explore why, and their findings could lead to a ...

Medical research

Sickle cell disease needs more attention

The promise of new treatments for sickle cell disease, a group of inherited red blood cell disorders, has never been so great, but it will only be realized if there is constant investment in health policies such as programs ...

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Cell (biology)

The cell is the structural and functional unit of all known living organisms. It is the smallest unit of an organism that is classified as living, and is often called the building block of life. Some organisms, such as most bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular. (Humans have an estimated 100 trillion or 1014 cells; a typical cell size is 10 µm; a typical cell mass is 1 nanogram.) The largest known cell is an unfertilized ostrich egg cell.

In 1835 before the final cell theory was developed, a Czech Jan Evangelista Purkyně observed small "granules" while looking at the plant tissue through a microscope. The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells. All cells come from preexisting cells. Vital functions of an organism occur within cells, and all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.

The word cell comes from the Latin cellula, meaning, a small room. The descriptive name for the smallest living biological structure was chosen by Robert Hooke in a book he published in 1665 when he compared the cork cells he saw through his microscope to the small rooms monks lived in.

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