Oncology & Cancer

Revealed: How cancer develops resistance to treatment

Cancer cells can turn on error-prone DNA copy pathways to adapt to cancer treatment, a breakthrough study published in the journal Science has revealed. Bacteria use the same process, termed stress-induced mutagenesis, to ...

Medications

Study sheds new light on a promising antidepressant

Ketamine, a well-known anesthetic used in smaller doses as a party drug, was hailed as a "new hope for depression" in a Time magazine cover story in 2017. Two years later, the arrival of the first ketamine-based antidepressant—the ...

Genetics

Still too soon to try altering human embryo DNA, panel says

It's still too soon to try to make genetically edited babies because the science isn't advanced enough to ensure safety, says an international panel of experts who also mapped a pathway for any countries that want to consider ...

Diseases, Conditions, Syndromes

Why hand-washing really is as important as doctors say

As the threat from the coronavirus grows, the Centers for Disease Control and Prevention and other public health officials are stressing the importance of hand-washing.

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Microorganism

A microorganism (from the Greek: μικρός, mikrós, "small" and ὀργανισμός, organismós, "organism"; also spelled micro organism or micro-organism) or microbe is an organism that is microscopic (usually too small to be seen by the naked human eye). The study of microorganisms is called microbiology, a subject that began with Anton van Leeuwenhoek's discovery of microorganisms in 1675, using a microscope of his own design.

Microorganisms are very diverse; they include bacteria, fungi, archaea, and protists; microscopic plants (called green algae); and animals such as plankton, the planarian and the amoeba. Some microbiologists also include viruses, but others consider these as non-living. Most microorganisms are unicellular (single-celled), but this is not universal, since some multicellular organisms are microscopic, while some unicellular protists and bacteria, like Thiomargarita namibiensis, are macroscopic and visible to the naked eye.

Microorganisms live in all parts of the biosphere where there is liquid water, including soil, hot springs, on the ocean floor, high in the atmosphere and deep inside rocks within the Earth's crust. Microorganisms are critical to nutrient recycling in ecosystems as they act as decomposers. As some microorganisms can fix nitrogen, they are a vital part of the nitrogen cycle, and recent studies indicate that airborne microbes may play a role in precipitation and weather.

Microbes are also exploited by people in biotechnology, both in traditional food and beverage preparation, and in modern technologies based on genetic engineering. However, pathogenic microbes are harmful, since they invade and grow within other organisms, causing diseases that kill millions of people, other animals, and plants.

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