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DNA-notes
DNA-notes

... rhamnose associated with the cell wall. Nonliving particles, smaller than a cell, usually consisting of a strand of DNA and an associated protein coating. It looks a lot like the original lunar lander. A type of virus that infects and kills bacteria. "Phage" means "eat" (phagocytosis). Like other vi ...
Lets`s Get Small
Lets`s Get Small

... glass. Compare its thickness, or width, to your own hair. If you were going to make a model of a piece of human hair, would you make it larger or smaller than a real piece of hair? Do you think microbes are smaller than the width of a piece of hair? If you needed to make a model of a microbe, would ...
Peach Stunt Disease and Associated Diseases of Peach
Peach Stunt Disease and Associated Diseases of Peach

... that natural spread within peach orchards via insects during pollination is an important means of transmission. Additionally, it has been demonstrated that natural spread of both PNRSV and PDV during pollination occurs more rapidly among trees of the same cultivar. PNRSV is more readily transmitted ...
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... trade, and in guaranteeing free market access. Various studies support the estimate that there could be at least 1.5 M fungal species on earth. Of the currently known 100 000 species, only around 16% have to date been deposited in genetic resource centres; approximately 11.5% of these species are kn ...
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... takes about 10 days. Chicken pox has few lasting effects. However, if activated in the nerve cells, it causes shingles, rumored to be excruciatingly painful. • Polio viruses invade nerve cells that can not be repaired or replaced, so the damage caused prior to our immune system's means of destroying ...
Biology Standard 10d
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How bacteria cause disease
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4. Virus Reproduction: Basic reproduction
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... 4. Virus Reproduction: Basic reproduction (virus without envelope), The Lytic Cycle (for bacteriophages) & The Lysogenic Cycle 4a. Virus Reproduction: BASIC REPRODUCTION The diagram on the left shows the simplest viral reproductive cycle of a virus. This occurs in viruses that do not have an envelop ...
C. Fungi - Effingham County Schools
C. Fungi - Effingham County Schools

... 12. A - Cell membrane – Controls what enters and leaves the cell. B – Cell wall – Gives shape to the cell C – Pilus – Play a role during conjugation or help attach to host cells D. – Flagellum – Helps with movement E – DNA – Contains genetic material of bacterium cell ...
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Introduction to viruses



A virus is a biological agent that reproduces inside the cells of living hosts. When infected by a virus, a host cell is forced to produce many thousands of identical copies of the original virus, at an extraordinary rate. Unlike most living things, viruses do not have cells that divide; new viruses are assembled in the infected host cell. But unlike still simpler infectious agents, viruses contain genes, which gives them the ability to mutate and evolve. Over 5,000 species of viruses have been discovered.The origins of viruses are unclear: some may have evolved from plasmids—pieces of DNA that can move between cells—while others may have evolved from bacteria. A virus consists of two or three parts: genes, made from either DNA or RNA, long molecules that carry genetic information; a protein coat that protects the genes; and in some viruses, an envelope of fat that surrounds and protects them when they are not contained within a host cell. Viruses vary in shape from the simple helical and icosahedral to more complex structures. Viruses range in size from 20 to 300 nanometres; it would take 30,000 to 750,000 of them, side by side, to stretch to 1 centimetre (0.39 in).Viruses spread in many ways. Just as many viruses are very specific as to which host species or tissue they attack, each species of virus relies on a particular method for propagation. Plant viruses are often spread from plant to plant by insects and other organisms, known as vectors. Some viruses of animals, including humans, are spread by exposure to infected bodily fluids. Viruses such as influenza are spread through the air by droplets of moisture when people cough or sneeze. Viruses such as norovirus are transmitted by the faecal–oral route, which involves the contamination of hands, food and water. Rotavirus is often spread by direct contact with infected children. The human immunodeficiency virus, HIV, is transmitted by bodily fluids transferred during sex. Others, such as the Dengue virus, are spread by blood-sucking insects.Viral infections can cause disease in humans, animals and even plants. However, they are usually eliminated by the immune system, conferring lifetime immunity to the host for that virus. Antibiotics have no effect on viruses, but antiviral drugs have been developed to treat life-threatening infections. Vaccines that produce lifelong immunity can prevent some viral infections.
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