Chapter 5, 11.8, 11.11: Viruses

what are viruses

genetic elements that replicate independently of a cell’s chromosome, but require a living host in order to reproduce

are viruses alive?

no they are not alive

parasitology of viruses

obligate intracellular parasites

what kind of cell types do viruses infect

ALL cell types

characteristics of virus

acellular infectious agents, contain DNA or RNA

DNA or RNA kinds within viruses

single stranded, double stranded, linear, circular, or segmented

extracellular form of viruses

virion

virion

the complete virus particle (nucleic acid surrounded by a protein coat)

virion size range

10 - 2300 nanometer

what does a virus contain

nucleocapsid

characteristics of nucleocapsid

nucleic acid (RNA/DNA) and protein coat (capsid)

virus symmetry

helical or icosahedral

icosahedral symmetry

crystal looking structure

which symmetry has the most efficient packaging

icosahedral

how are virus symmetry classified

their protein coat (capsid) arrangement

helical symmetry

spiraled protein coat

complex symmetry

combination of multiple structures/binal symmetry

vaccinia virus

proteins that suppress host defense

single stranded RNA virus (ssRNA) sense

positive and negative sense

positive sense of ssRNA

genome and mRNA are the same (ready to translated into protein)

negative sense of ssRNA

genome and mRNA are compliments (negative strand has to be changed to positive sense)

flow chart of negative sense

RNA genome (-) to mRNA (+) to protein

first scenario of positive sense

RNA genome (+) used as mRNA (+)

second flow chart of positive sense

RNA genome (+) to DNA (-) to mRNA (+) to protein

viral envelopes

outer, flexible membraneous layer made of lipids and carbohydrates

where are lipids carbohydrates derived from

the host

envelope proteins may __ from the envelope surface

project as spikes or peplomers

spikes or peplomers are

viral encoded

functions of spikes or peplomers

viral attachment to host cell, enzymatic activity, and role in nucleic acid replication, and identification of virus