Barrington Hills
They can't. Pathogens are microorganisms - such as bacteria and viruses - that cause disease. Dead viruses can be used to protect us from an infectious disease. Even "killed" viruses are recognized by our immune system. Our immune system memorizes (using antibody memory cells) these dead viruses and plans an attack incase we are ever infected with the living version. Unlike human cells or bacteria, viruses do not contain the chemical machinery (enzymes) needed to carry out the chemical reactions for life. Instead, viruses carry only one or two enzymes that decode their genetic instructions. So, a virus must have a host cell (bacteria, plant or animal) in which to live and make more viruses. Outside of a host cell, viruses cannot function. For this reason, viruses tread the fine line that separates living things from nonliving things. There are two levels whereby chemicals cause disease, particularly cancer. The first is by direct irritation, causing change at the cellular and DNA level. A chemical that is a potential carcinogen [cancer causing agent] may actually bind to the DNA in the cell nucleus and/or in the mitochondria, thereby altering its structure and potential for normal duplication. It may also make the DNA more vulnerable to the same or other carcinogens. Cancer is not an infectious disease
Monday, January 17, 2011
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