viruses Flashcards
what is a virus
a cellular non-living particle
what is the structure of a virus
either DNA or RNA ( nucleic acid ) surrounded by a protein coat ( capsid ) and sometimes a lipid coat aswell
attachment proteins allow the virus to identify and connect to the host cell
why are viruses not living
they dont carry out all of the MRS H GREN processes
what is a compelte virus particle called
a virion
what are the 4 shapes of a virus
helix
polyhedral
enveloped
others
how are viruses classified?
morphology (shape and stucture)
what it infects
genetic composition ( DNA or RNA single structure )
pathology ( what disease it causes )
what is the structure of a bacteriophage
complex double stranded DNA
what is the host cell and disease for the bacteriophage
e-coli bacterial cell - lysogenic and lytic cell cycle
small intestine cells
what is the structure of a tobacco mosaic virus ( TMV )
helix
single stranded RNA ( positive sense)
what is the host cell and disease for TMV
tobacco mosaic disease in tobacco plants and other legumes
what is the structure of ebola virus
enveloped helix
single stranded RNA ( negative sense)
what is the host cell and disease for ebola
host cell = human cells
disease = haemoraggic fever and 90 % death rate
budding
what is the structure of HIV
enveloped icosahedron
single stranded RNA
retrovirus
what is the disease and host cell for HIV
host cell = human white blood cells
disease = AIDS
latency and budding
what is a DNA virus
genetic material is DNA so direclty used as a template for new viral DNA and mRNA in viral protein synthesis
what is a positve RNA virus
has a sequence that can be translated directly by the ribosomes to synthesise proteins
what is a negative RNA virus
it has a complementary sequence to RNA to the mRNA copy has to be made using RNA polymerase enzyme before viral proteins can be translated
what is a RNA retrovirus
these viruses have a unique enzyme called reverse transcriptase that makes double-stranded DNA from single stranded RNA template . This DNA can then be integrated into the host cells genomic DNA .
when the DNA of a retrovirus is incorportated into the host cell what is it called ?
provirus - remains latent for years and is replicated everytime the cell divides
describe the lytic cycle of a virus
viral proteins are made
genetic material multiply’s and the host cell eventually lyses