Micro exam 2 Viruses

Who developed the vaccine for rabies?

Pasteur

what is attentuation

drying the affected nerve tissue to then weaken the virus

what are obligate intracellular parasites?

they must go inside the cell to infect, must invade a specific host cell

virion

complete, fully developed, infectious viral particle

what type of nucleic acid do virions contain?

DNA or RNA but never both

what is a capsid?

the protein coat surrounding the nucleic acid of a virion

can inactive viruses infect a cell?

no

where are inactive macromolecules located?

outside of the host cell

where are active macromolecules located?

inside the host cell

what determines the host range?

requirements for specific attachments, receptors, and availability of cellular factors for viral multiplication

what is the size of viruses

20nm to 1000 nm

what is the size of a parvovirus

0.02 um in diameter

what is the size of a mimivirus

450nm larger than some small bacteria

what is the size of a pandoravirus?

1 um long in ameoba

what is the subunit of a capsid?

capsomere; some single protein some mosaic

what is an envelope?

only found in some viruses; lipid bilayer with proteins and carbohydrates surrounding the capsid

what are viruses without an envelope called?

naked viruses

what are spikes?

glycoproteins; only on some viruses, project from the envelope or capsid, attach to specific receptors on host cells, change their composition to evade immune system

what are helical capsids?

long rods, ebola and rabies

what are polyhedral or icosahedral capsids?

many sided; icosahedron is 20 triangle faces with 12 corners, adenovirus or poliovirus

what is an enveloped virus?

helical or polyhedral; influenzavirus or herpes simplex virus

what is a complex virus?

complicated structures; bacteriophage

complex capsid

in bacteriaphages, have multiple types of proteins, take shapes that are not symmetrical

the viral envelope

composed of the membrane system of the host, regular membrane proteins are replaced with viral proteins

viral nucleic acid structure

either DNA or RNA, never both; ssDNA, dsDNA, ssRNA, dsRNA, can be linear or circular, can be in multiple segments

genome

the full complement of DNA or RNA carried by a cell, number of genes is small compared to a cell, only possess the genes to invade host and redirect the activity

how many nucleotides are in a genome? genes?

250,000 nucleotides, 10 genes

what is positive-sense RNA?

single-stranded RNA genomes ready for immediate translation into proteins

what is negative-sense RNA?

RNA genomes that need to be converted into the proper form to be made into proteins

what are polymerase?

they synthesize DNA and RNA

what are replicases?

they copy RNA

what is reverse transcriptase?***

synthesizes DNA from RNA only in retroviruses