Viruses. HIV virus Influenza Virus (the Flu) Only have ______ housed inside a PROTEIN coat. Requires a host cell to replicate Smaller than a prokaryote (10-400 nanometers). Ebola Virus. Virus binds to receptors on a cell’s ________ _________
Viruses are NOT alive! _________
use the cellular machinery of another organism’s living cells to multiply themselves
Tail of the virus attaches to host
injects its DNA or RNA into the host.
Host cell cannot tell the difference between its own DNA and that of the virus
Cell replicates the viral DNA as if it were its own.
Thousands of copies of the viral DNA and protein coat are made.
Eventually the cell becomes too full and lyses (bursts) releasing hundreds of virus particles that can now infect other cells.Lytic Cycle of a Virus
Viral DNA is injected and becomes incorporated into the cell’s DNA unknowingly.
The inserted viral DNA is called a Provirus.
The virus can remain inactive like this for long periods of time
When the cell replicates, so does the virus!
Sudden changes (temperature or availability of food) may cause the DNA of the prophage to become active.
Now new viral DNA could be synthesized like in the Lytic cycleLysogenic Cycle of Viruses
(Retro – RNA to DNA instead of DNA to RNA)
DNA is typically circular,
not in chromosome form