Chapter 19 Flashcards
viruses ____________ possess all properties of life
do not
3 properties of life that viruses do not possess
- viruses are not cells
- viruses do not grow
- virsuses cannot reproduce on their own
however viruses do ______________ some properties of life
possess
4 properties of life that viruses possess
- viruses can replicate
- viruses possess genetic material
- viruses utilize the genetic code
- virsues evolve by natural selection
_________________ produce genetic variability in viruses
mutations
viruses can be as small as __________________
20 nm
viruses consist of ____________ surrounded by __________________
genes (DNA and RNA)
protein coat
a virus can consist of as few as _______________ genes
4
_____________ is the protein coat of a virus
capsid
some viruses are surrounded by a ____________________
membranous envelope
_______________ which serve as receptor molecules are attached to the envelope
glycoproteins
a virus enter the a host cell and is ___________________,
uncoated
for a virus to be uncoated the DNA and ___________________ are seperated
protein capsid
the host cell’s enzyme (DNA polymerase) _____________ the viral DNA
replicate
the host cell’s enzyme (RNA polymerase) and ribosomes _________________ the viral DNA into RNA and proteins
transcription and translation
_____________ undergo either a lytic cycle or a lysogenic cycle within their bacterial host cells
bacteriophages
Bacteriaphages aka _______________ are viruses that infect bacteria
phages
_______________ possess DNA as their genetic material
bacteriaphages
a bacteriophages capsid consist of (3 things)
- head
- tail
- tailfibers
a _________ that contains DNA is in a virus
head
a ___________ that injects the DNA into the bacterium is in a virus
tail
__________________ attach the bacteriophage to the bacterium
tailfibers
during the ________________ the viral DNA incorporates itself into the bacterial chromosome
lysogenic cycle
during the lytic cycle, the new viruses that are produced destroy the cell when they _______________________
break out of it
lysogenic cycle does not harm the bacterial cell _____________, though viral DNA will ultimately exit the bacterial chromosome and initiate the ___________________
lytic cycle
the viral DNA is replicated when the bacteria _______________ in the lysogenic cycle
divides
lysogenic cycle does not harm the bacterial cell _____________, though viral DNA will ultimately exit the bacterial chromosome and initiate the ___________________
directly
lytic cycle
viruses that infect plants possess ____________ as their genetic material
RNA
viruses that infect animals may possess ___________ as their genetic material
DNA
viruses infect plants by way of _________________ transmission
horizontal and vertical
____________ transmission involves viral entry though damaged part of the plant
- lesion due to wind or cold
- insects feeding on the plant
- gardeners using infecting tools
horizontal
___________ transmission involves parents passing virus to their offspring
vertical
animal viruses do not lyse their _______________
host cells
DNA viruses causes:
- warts
- cold sores and genetial herpies
- chicken pox and shingles
- mononucleosis
- small pox
in ______________________ affected individuals are susceptible to other infections that bodys immune system would normally be able to fight off
HIV
RNA viruses cause:
- common cold
- influenza
- measels, mumps, rubella
- hepatitudes
- polio
- rabies
________________ are complex arrangements of molecules so they could represent an early transition between non life and life
viruses
there is high turnover in ________________ cells so tissue damaged by a common cold can be replaces
respiratory system
________________ cells do not divide and therefore cannot be replaced so polio is permanent
central nervous system
the glycoproteins bind to recelptors on an animal host which mediated _____________________ of the virus into the cell
endocystosis
new viruses exit the host cell by way of ______________ stealing some of the host membrane as their envelope
exocytosis
viruses also frequently trigger the breakdown of ______________________ releasing damaging enzymes into the cell
lysosome
there are vaccines that ____________ many viral infections
prevent
medications can only ________________ viral infections once they are acquired
treat
medications cannot ____________ viral infections
cure
HIV _____________________ is the virus that causes AIDS ___________________________
human immunodificiency virus (HIV)
acquired immunodifficiency syndrom (AIDS)
HIV infects ___________________________
leukocytes (white blood cells)
HIV is a ______________ virus that function as a ___________________
RNA virus
retrovirus
HIV uses an enzyme _______________ to produce
DNA from RNA template (many HIV drugs target this enzyme
reverse transcriptace
however because viruses can only reproduce by living cells, _______________________________
cells must have existed prior to viruses
Which came first Virus or cell?
the cell
viroids are small ____________ molecules that infect _______________________
RNA
plants
prions are small _________________ molecules that infect _________________________
proteins
animals
_______________ the cause of mad cow disease in cows and creutzfielt-kakob disease in humans causes __________________
prions
causes brain damage
