1. 6.2 -Viruses

2. Warm-up Essential Question What are the characteristics of life?
Why can’t we “cure” Viruses?

3. Viruses
Viruses – particle made up of nucleic acid (DNA or RNA), protein, and in some cases lipids that can replicate only by infecting living cells
Core of DNA or RNA surrounded by protein coat (capsid), some look like little spaceships

4. Herpes
Herpes virus

5. Viruses are not alive 1) They do not maintain homeostasis
3) They do not grow.
4) They do not utilize energy on their own.
5) They do not reproduce on their own.
6) They are not made of cells.
Although they DO have DNA and RNA

6. Viruses are TINY

7. Bacteriophage – virus that infects a bacteria

8. Replicative Cycles Cannot reproduce on own.

9. C. Lytic Infection 1. Virus enters cell
2. Forces cell to Makes copies of itself
3. Causes cell to burst with new viruses

10. Lysogenic Infection Review
Virus embeds its DNA into the DNA (genome) of the host cell & is replicated along with the host DNA
Then after numerous cell divisions acts like lytic infection and bursts cells

12. Viruses and Disease
Examples: polio, rabies, measles, AIDS, mumps, influenza, yellow fever, & common cold

13. Viruses and Disease
Best human protection: vaccines: injection with weakened virus that triggers human immune system to make antibodies.
Antibiotics work on BACTERIA because it blocks growth, reproduction, or energy uptake. VIRUSES don’t do those things (has nothing to do with size)

14. Herpes Simplex ( cold sore)
65% of Americans carry this virus
Changing conditions (stress, heat, etc.) can bring about lytic cycle
Kiss me, my valentine!!

15. Iron lung Used for treatment of muscle failure in Polio
Can someone scratch my nose?

16. Model the lytic and lysogenic cycles of a bacteriophage
You have a baggie with 4 paperclips, six pieces of pipe cleaner (two big, four small), and a dry erase marker
The paperclip is the virus capsid, the pipe cleaners are bacteria DNA and virus DNA/ RNA
Using the marker and a whiteboard, draw the bacteria’s cell wall (remember the scale!)
You will have to demonstrate to me:
Lytic cycle
Lysogenic cycle
Binary fission
Vocabulary words