Microbiology: Viruses Flashcards
1
Q
What is the structure of a virus?
A
Capsid, nucleic acid, and protein rich envelope.
- others may include tail base plate, and tail fiber (bateriophages)
2
Q
a mature virus out side the host cell is called a ?
A
virion
3
Q
How do viruses differentiate from living organisms?
A
- require host cells reproductive machinery to reproduce
- do not metabolize organic nutrients
- (in active form) are not separated from external environment by a barrier such as a cell wall or membrane
- posses ether DNA or RNA not both
- can be cyrstallized with out losing ability to infect.
4
Q
bacteriophage
A
virus that infects bacteria
- has tail and fibers
5
Q
Describe a Lytic infectoin
A
- virus commmandeers the cells reproductive machinery and begins reproducing new virus.
the cell may fill w/ viruses until it bursts, or it may release viruses one at a time - A virus folling the lytic cycle is called a ‘Virulent virus’
6
Q
What is Latent Period?
A
- period from infection to lysis
- this includes the eclips period(brief period after infection before first fully formed virion appears)
7
Q
Describe a Lysogenic Infection
A
- when the viral DNA is incorporated into the host genome, so when the host replicates its DNA the viral DNA is replicated as well.
- A virus in the lysogenic cycle is called a ‘temperate virus’
8
Q
During a lysogenic infection, while the viral DNA remains incorporated in the host DNAthe virus is said to be _______.
And this type of virus is called a _______.
A
- dormant or latent
- prophage
- a dormant virus can be come active if under some type of stress(UV, carcinogens)
9
Q
vaccine
A
- either an injection of antibodies or of non-pathogenic virus with the same capsid or envelope.
10
Q
Describe a retrovirus
A
- a retrovirus carries reverse transcriptase to create DNA from its RNA. The DNA is then incorporated into the host cell.
ex: AIDS
11
Q
Describe plus-stranded RNA
A
- indicates that proteins can be directly translates from RNA
12
Q
Describe Minus-stranded RNA
A
- is the complement to mRNA and must be transcribed to plus-RNA before being translated
