Viruses Flashcards
what do all viruses have ?
- a core of nucleic acid, around which is
- a protein coat, called a capsid
what does some viruses have ? Why ?
an additional external envelope of membrane made of lipids and protein - because they lack any metabolism of their own, viral infections are difficult to treat
when effective antivirals develop what must work ?
inhibiting viral replication by the host cells
what are the 4 types of viruses ?
- lambda
- tobacco mosaic virus
- Ebola virus
- human immunodeficiency virus
Lambda
host: bacterium
nature of nucleic acid core: double - stranded DNA
Tobacco mosaic virus
host: plants
nature of nucleic acid core: single - stranded RNA
Ebola virus
host: humans
nature of nucleic acid core: single - stranded RNA
Human immunodeficiency virus
host: humans
nature of nucleic acid core: single - stranded RNA
the lytic cycle
- attachment
- entry - the virus injects the nucleic acid into the bacterial cell
- replication - the host’s metabolism replicates the viral DNA or RNA
- assembly - new virus particles and assembled
- lysis and release - the host cell breaks open and releases new virus particles
viral latency
a period in which, under the control of specific latency genes, a pathogenic virus remains dominant
what are the two types of viral latency ?
episomal latency and proviral latency
episomal latency
the viral nucleic acid remains inactive but free in the cytoplasm or nucleus of the infected cell
proviral latency
the viral nucleic acid becomes incorporated into the DNA of the infected host cell - provirus - it can be reactivated at any time
why are viral infections so difficult to control ?
virus pose a considerable challenge to the body’s immune system because they hide
describe how antivirals drugs work.
- block receptors so viruses cannot bind to and enter healthy cells
- target enzymes viruses use that host cells do not use
