Biology: Virus(23) Flashcards
0
Q
what is another word for virus?
A
phage
1
Q
virology
A
the study of viruses, small infectious particles, and their interactions with humans
2
Q
Why is a virus considered non-living?
A
- they do not possess all of the characteristics of life
- acellular- no cell membrane, cytoplasm, or organelles
- replication- have to reproduce within a host cell
- no metabolism
- no growth or development
3
Q
Viral Structure
A
two main structural parts
- nucleic acid (DNA or RNA); may take form of a helix, a circular loop, or a linear strand
- protein coat called a capsid
- viral envelope
- helps virus bind to host cell
- HIV, chicken pox, influenza
4
Q
How are viruses classified?
A
- classified based on the nucleic acid they have
- classified by the type of host they invade
- classified by presence/absence of an envelope
- classified by virus shape
5
Q
DNA viruses
A
- inject their DNA into the host cell and instruct the host DNA to transcribe and translate new copies of the virus
6
Q
RNA virus
A
- possess RNA often ready for translation into new viruses
7
Q
retrovirus
A
- have RNA
- have enzyme reverse transcriptase
- use RNA to form DNA
- assimilate into host cell’s genome
8
Q
bacteriophage
A
- virus that infects bacteria
9
Q
Viral Replication
A
- can only replicate while using host cell machinery and metabolism of the host cell
- two mechanisms for prokaryote hosts
- lytic and lysogenic cycle
- two mechanisms for prokaryote hosts
10
Q
Lytic cycle
A
- viral replication in a prokaryote
- virulent–> disease causing
1) phage attaches to host cell and injects DNA
2) phage DNA circularizes and enters lytic cycle or lysogenic cycle
3) new phage DNA and viral proteins are synthesized and assembled into virions
4) cell lyses and releases the phage virions
11
Q
lysogenic cycle
A
- viral replication
- temperate–> latent period (not harmful to host)
1) phage attaches to host cell and injects DNA
2) phage DNA circularizes and enters lytic or lysogenic cycle
3) phage DNA integrate within the bacterial chromosome by recombination–> prophage
4) lysogenic bacterium reproduces normally
5) the prophage may excise from the bacterial chromosome–> lytic cycle
12
Q
Viruses and Human Diseases
A
- HIV
- Influenza
- Rabies
- Common cold
- Chicken pox/shingles
- mumps
- small pox
- measles
- hepatitis
13
Q
vectors
A
- carriers that transmit viruses to the host
14
Q
HIV: Human Immunodeficiency Virus
A
- causes AIDS
- retrovirus that infects leucocytes (WBCs)
- disables WBCs from performing their normal function of fighting off infection from other pathogens
- high viral load of HIV signals the onset of AIDS
