2. Virus Video

3. Viruses & Bacteria can cause infection
Pathogen - Any disease-causing agent
1 nanometer (nm) = one billionth of a meter
100 nm
eukaryotics cells 10, ,000 nm
viroids nm
viruses nm
prokaryotics cells ,000 nm
prion 2-10 nm

4. Virus 2 basic parts: non-living pathogen protein coat.
Contains DNA or RNA
non-living pathogen

5. Viruses have a simple structure.
enveloped (influenza)
polyhedral (foot-and-mouth
disease)
helical (rabies)
capsid
nucleic acid
lipid envelope
surface proteins
capsid
surface proteins
nucleic acid
capsid
nucleic acid
lipid envelope
Surface proteins

6. All viruses have two main parts:
DNA or RNA – genetic info
Capsid – a protein coat

7. Bacteriophages: viruses that infect bacteria.
capsid
DNA
tail sheath
tail fiber

8. Viruses enter cells in various ways.
bacteriophages pierce host cells
colored SEM; magnifications:
large photo 25,000; inset 38,000x

9. Virus inserting it’s DNA into a bacterial cell.

10. Viral Replication Picture

11. Endocytosis (pulled into cell)
Viruses enter cells in various ways.
Endocytosis (pulled into cell)

12. Viruses enter cells in various ways.
fuse with membrane

13. Viruses contain DNA/RNA, proteins, and they reproduce…
Are viruses alive???
NO.
They contain no nucleus, cytoplasm, organelles or cell membrane; they cannot carry out cell functions, and they can only “reproduce” when an infected cell builds new viruses.

14. Grouping Viruses Grouped according to:
Presence of Capsid and envelope – shape
RNA or DNA, single or double stranded – structure
Viral Group
Nucleic Acid
Shape and Structure
Example
Papovaviruses
DNA
Icosahedral, non-env.
Warts, cancer
Adenoviruses
Resp. & intestinal infections
Herpesviruses
Icosahedral, enveloped
Herpes simplex, chicken pox, mono, shingles
Poxviruses
Complex brick, enveloped
Small pox, cow pox
Picornaviruses
RNA
Polio, hepatitis, cancer
Myxoviruses
Helical, enveloped
Influenza A, B, C
Rhabdoviruses
Rabies
Retroviruses
AIDS, cancer

15. Treatment and Prevention
Anti-viral drugs: interfere with viral DNA/RNA synthesis
Vaccines – creates antibodies
Inactivated- the virus is “dead”; cannot replicate
Attenuated- the virus has been genetically altered; still functional, but won’t cause disease
Attenuated tend to be more effective vaccines

16. Some Pictures are Graphic

17. The Lysogenic Cycle
When viruses remain inactive within host cells for days, months or years.
•Viral DNA inserted directly into the host DNA.
•Viral DNA copied with host DNA during replication
•Viral DNA passed on to daughter cells during mitosis
•Remains dormant (no viral proteins are produced) until some “triggering event”
Stress
UV light
heat
Examples: Chickenpox and Shingles; HIV
chemicals
???

18. POXVIRUSES Small Pox
BACK

19. PICORNAVIRUSES - Polio
BACK

20. Destroys the motor neurons that are producing the virus
Destroys the motor neurons that are producing the virus. The result is a loss of muscle control including the diaphragm. The iron lung changes the pressure to pump air in and out of the lungs.

21. U.S. President
Franklin Delano Roosevelt

22. MYXOVIRUSES Flu Virus
BACK

23. RHABDOVIRUSES Rabies
BACK

24. RETROVIRUSES
AIDS

25. Herpes

26. HPV Tree man

28. Ebola

29. Syphilis

30. T4 Bacteriophages Sketch & Label the following: capsid DNA tail sheath
tail fiber