Chapter 13 - Viruses, Viroids, and Prions Flashcards
Obligatory Intracellular Parasites
-require living host cells to multiply
Viruses
-contain a single type of nuclei acid, DNA, or RNA
-contain a protein coat
-multiply inside living cells by using synthesizing machinery of the cell
-synthesize special structures that transfer viral nucleic acid to other cells
Viruses Have no Enzymes
-no enzymes for their own metabolism, protein synthesis, ATP generation
-take over metabolic machinery of host cell
Host Range
-spectrum of host cells the virus can infect
Virion
-a complete, fully developed, infectious viral particle
-composed of nucleic acid and surrounded by a protein coat outside a host cell
Virus DNA
-have DNA or RNA but never both
Capsid
-protects the nucleic acid of a virus
-a protein coat
-allows lab ID
-allows transmission between hosts
-used for attachment
Capsomeres
-composition of capsid (subunit)
-protein subunits
-arrangement is particular to the virus
Envelope
-covers some capsids in a virus
-combination of lipids, proteins, carbohydrates
-a phospholipid bilayer
-extra layer of protection
-aids in ID
Spikes
-may cover envelopes
-carbohydrate-protein complexes
-how some viruses attach to host cells
-can be used as a means of ID (vaccine target)
Hemagglutination Spike
-resulting clumping of red blood cells by spikes
-viruses bind to RBCs and form bridges between them
-sharp
Neuraminidase Spike
-separation from host cell after infection
-rounded bulb shape
Non-enveloped Viruses
-viruses whose capsids aren’t covered by an envelope
-capsid protects nucleic acid from enzymes
-capsid promotes virus attachment to host
Complex Viruses
-bacterial viruses that have complicated structures
How are viruses grouped?
-according to how their mRNA is produced
Viral Species
-a group of viruses sharing the same genetic information and ecological niche
Parasite
-a virus
-usually asymptomatic
-use host as mixing vessel (bird, bats) to transfer genes to humans