Microbiology Topic 14 Flashcards
How Do Viruses Reproduce
- Recognize & attach to host cell.
- Infect (get inside) host cell.
- Force cell to manufacture viruses
- New viruses exit the host cell
Most viruses infect only a certain type of host
Specificity due to affinity of viral surface proteins to proteins on the surface of the host cell.
Recognize & attach to host cell.
have proteins in their tail fibers (those extensions that look like legs) that are attracted to proteins on the surface of bacterial cells.
BACTERIOPHAGES
have proteins or glycoprotein spikes that correspond to glycoproteins on the surface of animal cells.
ANIMAL VIRUSES
may also be so specific that they infect a particular cell type of the host organism. (HIV only attacks helper– T lymphocytes, a type of white blood cell, in humans.)
Viruses
A virus can exist outside or inside of its host.
Infect (get inside) host cell.
Extracellular state
- Called virion
- Protein coat (capsid) surrounding nucleic acid
- Some have phospholipid envelope
- Outermost layer provides protection and recognition sites for host cells
Intracellular state
- Capsid removed
- Virus exists as nucleic acid (genetic material)
It injects its genetic material into the host cell using its tail; attaches itself to a susceptible bacterium. The bacteriophage then hijacks the bacterium’s cellular machinery to prevent it from producing bacterial components and instead forces the cell to produce viral components.
bacteriophage
Direct penetration of naked virus (Viral genome enters cell, while capsid remains on cell’s surface); Endocytosis; Membrane fusion (With membrane fusion and edocytosis, the capsid is removed once inside the host cell.)
animal virus
Host cell reads viral genetic instructions and manufactures raw materials needed to build copies of new viruses.; The viral parts and pieces self-assemble
Force cell to manufacture viruses
