Biology 1001A Lecture Notes - Lecture 1: Antiviral Drug, Reverse Transcriptase, Complementary Dna
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Cha(cid:396)a(cid:272)te(cid:396)isti(cid:272)s of (cid:448)i(cid:396)uses a(cid:374)d (cid:449)h(cid:455) the(cid:455) a(cid:396)e (cid:374)ot ge(cid:374)e(cid:396)all(cid:455) (cid:272)o(cid:374)side(cid:396)ed to (cid:271)e (cid:862)ali(cid:448)e(cid:863). Viruses are one ore more nucleic acid molecules surrounded by a protein coat (capsid). Some capsids may be e(cid:374)(cid:272)losed i(cid:374) a(cid:374) e(cid:374)(cid:448)elope f(cid:396)o(cid:373) the host (cid:272)ell"s (cid:373)e(cid:373)(cid:271)(cid:396)a(cid:374)e. the(cid:396)e a(cid:396)e t(cid:449)o (cid:271)asi(cid:272) structures of viruses: helical (protein subunits in rodlike structure around genome) and polyhedral (coat proteins make triangle units). They lack several basic properties of life, such as lack of mobility and not being able to reproduce, as well as not having a metabolizing system. This classifies them as infectious biological particles rather than organisms: why viral infections are usually difficult to treat with drugs, and exceptions to this general principle. Viral infections are usually difficult to treat with drugs because they are hidden in the host cell and so it is difficult to locate and attack virus-specific products. An exception to this general principle is when a virus uses its own polymerase.