obligate intracellular parasites; virus particle
2. genetic material
6. host range?
1. very small, cant see in light microscope
2. dna or rna but not both
3. ALL HAVE, protein coat that protects the genetic material (different shapes)
4. only some have, derived from post cell membranes (phospholipid)
5. icsohaderal, cylander, other
6. species and cell type that the virus will infect
internal componetns and multiplication of viruses?
multiply only within cells and dependent on host cells for energy and synthesissing amino acids
are responsible fro attachement to host cell. host cell will have a receptor for the virus
fecal-oral route (food water not washing hands)
respirartory or salivary route (colds, sneezing, cough)
vectors (animal- human) rabies
virus infetion and multivplication cycle:
2. penetration (entry)
1. attachemnt of the virion to host cell via receptor on host cell
2. envelope viruses- fusion of envelpe with cell membrane or receptor mediator endocytosis; naked viruses- receptor mediated endocytosis
3. seperation of capsid and nucleic acid
4. replication of viral nucleic acid, transcription of viral genes translation of viral proteins
5. capsid assembly which may require protease enzymes (cut/clip off)
6. budding for envelpe viruses; naked viruses depend on cell lysis for release
DNA replicate where?
all replicate in nucleaus of cell
(-) strand template for MRNA synthesis
(+) strand has same sequence as mRNA
virsues replicate where?
RNA ss plus strand virus?
viral nucleic acid acts as mRNA translated IMMMEDIATELY to produce rna dependednt rna plymerase which synthesizes antisense strand
RNA ss minus strand virus?
virion contains rna dependednt rna plymerase that synthesizes + strand from - template
RNA- DNA, carry own polymerase, reverse transcripatase, rna dependent dna plymerase (using rna as the template for synthesiszing dna)
what must happen to dna before transpcption of mRNA?
dsDNA must be integrated inot host cell (never will come back out)
integrated from of dna into chromosome
difference between provirus and transposons?
transposon can come back out of chromsome
how does a viron acquire an envelpe when leaving?
usually does not directly lead to cell death but productively infected cells usually die
how do naked cell get released?
depend on cell death