BIOL 2051 Chapter : Chapter 6
Document Summary
Viroids and prions: viroids, prions, rna without capsid (viruses without capsids) Infect plants: protein-only infectious agent, bse (mad cow), scrapie (sheep), creutzfeld-jakob, kuru (humans), chronic wasting disease (deer, elk) are all caused by prions, all cause spongy appearance in the brain. Loss of motor control and etc: defective protein causes normal protein to take on abnormal shape, loses normal function. Virus structure capsids: capsid, protein coat surrounding nucleic acid, capsid proteins are arranged to give virion symmetry. Icosahedral capsids (poliovirus, herpes virus: roughly spherical, 20 equilateral triangles or faces, filamentous capsids (m13, ebola) Long tube of protein with genome inside: tube made up of 100s of identical protein subunits, tube length reflects size of viral genome, complex capsids, mixture of icosahedral & filamentous shapes, many bacteriophage. Viruses that infect bacteria: asymmetrical shapes, tend to be larger viruses, poxviruses. Virus structure genome: dna or rna, viruses are the only entities that can have rna as a genome.
