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Viruses, Bacteria, Diseases Discussed

41. Describe general characteristics of picornaviruses.
42. Define plaque, lawn of bacteria.
43. Define normal and transient microbiota.
44. Compare commensalism, mutualism, symbiosis, and parasitism, and give an example of each.
45. List Koch's postulates and the exceptions.
46. Categorize diseases according to frequency of occurrence.
47. Identify the principal portals of entry, know which is the preferred.
48. Differentiate sign, symptoms, and syndrome.
49. Describe the primary characteristics of microbial antagonism.
50. Define, and give examples of, zoonosis.

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41. Describe general characteristics of picornaviruses.

Picornaviruses contain a single-stranded, positive sense RNA genome. The RNA alone is infectious; although less so than if contained within the capsid of the virus. The capsid is icosahedral.

Like human mRNA, the genome has a poly A tail at its 3' end, but unlike human mRNA, the genome doesn't have a 5' cap. Instead, it has a virally encoded protein known as VPg.

Examples of picornaviruses are: Enteroviruses (including Poliovirus), Rhinovirus (cause of the common cold), and Hepatovirus.

42. Define plaque, lawn of bacteria.

A bacterial lawn appears on a petri-dish agar plate when all of the original colonies of bacteria merge together to form a solid field of bacteria.

When the bacterial lawn is exposed to a bacteriophage or antibiotics, the exposed bacteria cells die. The clear (usually round) patch of lysed/dead cells in the bacterial lawn is known as a plaque.

43. Define normal and transient microbiota.

Microbiota is microbial flora harbored by healthy individuals (i.e. they are not microbes that make you sick). Some (the "normal" ones) are regularly found on their host species (I'm assuming we're talking about humans), and if disturbed they will reestablish themselves. Others (the ...

Solution Summary

The solution contains answers to 10 review questions related to viruses, bacteria, microbes, and disease.