1. Viruses

2. Viruses Use infected cell to produce more viruses
Capsid: protein coat surrounding DNA/RNA core
bacteriophage – virus that infects bacteria

3. Viral Infections Lytic Infection
after entering the cell, host cell make 1000’s of copies of viruse’s DNA
new virus particles are made
the infected cell then lyses, or busts
100’s of virus particles are released

4. Viral Infections Lysogenic Infection
Prophage: viral DNA become part of the host’s DNA
viral DNA is copies with host’s DNA
When the prophage is activated, the cell enters the lytic cycle

5. Retroviruses RNA In host cell, makes a DNA copy of RNA
its DNA is inserted into the host’s DNA
AIDS

6. Are Viruses Alive? Not Alive no response to the environment
does not obtain or use energy
no growth or development
reproduces only with a host cell