1. Viruses

2. What is a virus? A virus is: NON-LIVING particle
Made of a protein coat and DNA or RNA
Smaller than bacteria ( nm)

4. Why is it non living?
Reasons 1) A virus is not made out of cells 2) A virus can not reproduce on its own 3) No energy required

5. What do they do?
Infect specific cells and get those cells to make more copies of it
Plants Bacteria Animals

6. Growth & Reproduction Nonliving = no energy required
Can not grow or make proteins by itself
Must infect a host cell
Steps to reproduction:
Identify specific host cell using protein receptors (lock and key)
Enter host cell
Insert DNA or RNA
Host cell reads instructions and makes more viruses
Viruses leave and destroy cell 6

7. Viral Reproduction Lytic Cycle
Virus infects cell and integrates into DNA
Virus takes over cell processes
Makes multiple copies of viral parts
Lyses (pops) the host cell 7

8. Viral Reproduction Lysogenic Cycle
Virus infects cell and integrates its DNA into host’s DNA
The Viral DNA replicates (gets copied) as the cell replicates
If virus is activated, it enters into Lytic Cycle
Inserted viral DNA
may disrupt cell processes
which can be cancerous 8

9. Viral Reproduction Lytic Cycle Lysogenic Cycle
Virus Attaches
Injects DNA
Viral DNA takes
over host cell
protein machinery
Viral DNA
integrates into
host cell DNA
duplicates with the
host cell
Does not kill cell
New virus parts
made & assembled
New viruses leave
& kill host cell by
Lysis (popping)
Lytic Cycle
Lysogenic Cycle
If activated, dormant virus can enter the Lytic cycle 9

10. Are viruses bad?
Yes! All viruses destroy their host cells

11. How do they make you sick?
They insert their DNA or RNA into yours. Your cell makes more viruses until it is destroyed

12. How can you stay safe?
Use a vaccine Wash hands

13. NONE! Antibiotics do not work!!!
Any cures?
NONE! Antibiotics do not work!!!