Unit One- 2.5 viruses Flashcards
characteristics of a virus
-infectious
-non-living
-no cytoplasm
-cannot grow or reproduce on its own
-do not produce or use energy
-do not create waste
-have genetic material
how big are viruses
less than 0.1 mircometers
what are the basic structures of a virus
Capsid- protein coat that protects genetic material
Genetic Material- DNA or RNA core (nucleoid acid)
An envelope- cell membrane wraps around the virus
how is a virus envelope created
when a virus leaves a host cell & part of the original host cell membrane wraps around the virus
what is a virus that infects bacteria called
bacteriophage
what are viruses specific to?
- organism
- cell type
- host range- # of species, tissues, or cells that a virus can infect
how do viruses reproduce
*inside living cells
–> use host cells genetic machinery (ribosomes, enzymes, etc.) to reproduce viral parts
how do viruses spread
they rupture the cell releasing these viruses to infect more cells
ways viruses enter animal cells
- Attachment & Injection- capsid remains on the outside of a host cell
- Endocytosis- cell swallows virus through phagocytosis, virus sheds its capsid, viral genetic material takes over
- Membrane Fusion- membranes between cells may fuse together to get inside the cell
lytic cycle
*shorter simpler cyle
*replication occurs in cytoplasm of a host cell
1.genetic material enters the host cell
2. the cell replicates the viral DNA or RNA
3. host cell makes new capsids and new viral particles
4. host cell bursts and new cells leave
lysogenic cycle
-genetic material enters host cell nucleus… becomes part of host cell’s membrane
-genes are not activated till later
-activation continues lytic cycle
biotechnology
*genetic engineers can use viruses to make copies of certain genes
-gene in inserted into genetic material of virus
