Why is viruses not one of the five kingdoms

How is this possible? How can something as nasty as a virus spread so fast, reproduce, and infect other living things, but not be considered a living creature? The answer has been a subject of debate since the moment viruses were first named in There is no single undisputed definition of life.

Does it multiply through cellular division? Does it have a metabolism? Read more: What came first, cells or viruses? They fail the second question for the same reason. Unlike living organisms that meet their energy needs by metabolic processes that supply energy-rich units of adenosine triphosphate ATP , the energy currency of life, viruses can survive on nothing.

In theory, a virus can drift around indefinitely until it contacts the right kind of cell for it to bind to and infect, thus creating more copies itself. In short, yes. Normal viruses are not capable of protein synthesis or DNA repair on their own, they must rely on the organelles of their host cells for these activities.

For more information, see D. Raoult, et al. La Scola et al. Division Bryophyta mosses and liverworts. Division Psilophyta Psilotum or whisk fern.

Division Lycophyta club mosses. Division Sphenophyta horsetails. Division Pterophyta ferns. Division Cycadophyta cycads. Division Ginkgophyta maidenhair tree. Division Coniferophyta Pinophyta: conifers. Division Anthophyta flowering plants. Biological Organization. Species a distinct kind or unit. Twenty of the more than species of Pinus on earth. All of these pines are native to the state of California, USA. Monterey Pine P. Bishop Pine P. Santa Cruz Island Pine P.

Whitebark Pine P. Limber Pine P. Beach Pine P. Lodgepole Pine P. Western White Pine P. Knobcone Pine P. Bristlecone Pine P. Foxtail Pine P. Four-Leaf Pinyon P. Two-Leaf Pinyon P.

One-Leaf Pinyon P. Ponderosa Pine P. Coulter Pine P. Digger Pine P. Torrey Pine P. Jeffrey Pine P. Sugar Pine P. Another species left image called the Washoe Pine P. In addition, the Beach and Lodgepole Pines are now recognized as subspecies of P.

According to R. Lanner Conifers of California , , there may be other significant changes in the pines of California. Allozyme studies in two-leaf pinyons Pinus edulis of the New York Mountains indicate that these populations are biochemically and genetically consistent with nearby one-leaf pinyon Pinus monophylla , and that P.

The unusual New York Mountains population appears to be a 2-needle variant of P. According to Lanner, the latter species has five needles per fascicle and occurs in San Diego County. The hybrid hypothesis might explain the perplexing variation in needle number for P. Foxtail pines Pinus balfouriana on the 11, ft m slopes of Alta Peak. The 13, ft. Left: Seed cones of cypress Cupressus from groves in southern California.

Tecate cypress C. Since viruses are so small, the size of their genome is limiting. For example, some viruses have coded instructions for only making a few different proteins for the viruses' capsid. On the other hand, the human genome codes for over 30, different proteins. Therefore, the lack of coded instructions cause some viruses to need the presence of other viruses to help them reproduce themselves. Such viruses are called replication defective.

As the process of RNA replication with enzymes and other organelles of the host cell is more prone to errors, RNA viruses have much higher mutation rates than do DNA viruses. Answers to Viruses Practice Questions. From Wikibooks, open books for an open world. Category : Book:General Biology.

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