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The photo shows a hot spring with a vivid blue color in the middle and a golden color around the edge.
Certain prokaryotes can live in extreme environments such as the Morning Glory pool, a hot spring in Yellowstone National Park. The spring’s vivid blue color is from the prokaryotes that thrive in its very hot waters. (credit: modification of work by Jon Sullivan)

In the recent past, scientists grouped living things into five kingdoms—animals, plants, fungi, protists, and prokaryotes—based on several criteria, such as the absence or presence of a nucleus and other membrane-bound organelles, the absence or presence of cell walls, multicellularity, and so on. In the late 20 th century, the pioneering work of Carl Woese and others compared sequences of small-subunit ribosomal RNA (SSU rRNA), which resulted in a more fundamental way to group organisms on Earth. Based on differences in the structure of cell membranes and in rRNA, Woese and his colleagues proposed that all life on Earth evolved along three lineages, called domains. The domain Bacteria comprises all organisms in the kingdom Bacteria, the domain Archaea comprises the rest of the prokaryotes, and the domain Eukarya comprises all eukaryotes—including organisms in the kingdoms Animalia, Plantae, Fungi, and Protista.

Two of the three domains—Bacteria and Archaea—are prokaryotic. Prokaryotes were the first inhabitants on Earth, appearing 3.5 to 3.8 billion years ago. These organisms are abundant and ubiquitous; that is, they are present everywhere. In addition to inhabiting moderate environments, they are found in extreme conditions: from boiling springs to permanently frozen environments in Antarctica; from salty environments like the Dead Sea to environments under tremendous pressure, such as the depths of the ocean; and from areas without oxygen, such as a waste management plant, to radioactively contaminated regions, such as Chernobyl. Prokaryotes reside in the human digestive system and on the skin, are responsible for certain illnesses, and serve an important role in the preparation of many foods.

Questions & Answers

what if cranium break
Alimamy Reply
it will cause a concussion and may affect the brain
INGIPHILE
how will it affect the brain?
Gaone
it may cause mechanical shock which might lead to a formation of a tumor and seizures
INGIPHILE
what are prokaryotes
Jacob Reply
Prokaryotes are cells with well defined nucleus or cells with membranes example; Bacteria,Nostoc etc.
Emmanuel
what is bilateral symmetry
Mameibi Reply
Explain kingdom of fungi
HARUNA Reply
what are the nutritional requirement of organism
Patience Reply
which part of the alimentary canal were these cross section taken
Getrude Reply
what is alimentary canal were these cross section taken
Getrude
what is matter
Gifty Reply
from which part of the alimentary canal were these cross section taken fig 2.1 fig 2.2 b,c
Getrude Reply
explain the role played by b in the alimentary canal
Getrude
what is biology
Sunday Reply
what is mitosis
David Reply
structure of a kidney
Idriss Reply
explain sexual reproduction of a named flower taking account of pollination, fertilization and the change to seed and fruit.
Chinyi Reply
The study of all life or living matterThe living organisms of a particular region.
Oyewale Reply
what is ology
Green Reply
in which of the following stages of the cell cycle are chromosomes pulled apart to opposite poles of the cell
Amie Reply
Anaphase
Jonah

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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