1. Viruses & Bacteria Chapter 19

2. I. Viruses Q: Is a virus living or nonliving? Viruses HAVE: DNA or RNA Reproduce (only in living cells)

3. Viruses DO NOT HAVE: Growth/development Cells Response to stimuli Energy use VIRUS = a NONLIVING particle of nucleic acid & a protein coat (capsid)

4. Viruses grouped based on… 1) Shape 2) Having either RNA or DNA 3) The organism it infects

5. T4 virus Retrovirus

8. Chicken pox

11. Viral Reproduction To reproduce, it needs a HOST CELL (a living cell) to infect. Viruses only attach to certain cells – not all! Have 2 cycles: lytic & lysogenic

12. http://www.ptpleasantbch.k12.nj.us/bridge/genbio/microbiology.html

14. Which is potentially more dangerous – lytic or lysogenic viruses? Lysogenic viruses! Can spread w/o knowing it

15. Fighting Viral Infections 1. Vaccination made from “dead”/weakened/altered pathogens stimulates immune system to protect against that virus

16. 2. Antibodies = proteins that help block/destroy pathogens made by white blood cells creates memory to attack future virus exposure

17. HIV and AIDS HIV = Human Immunodeficiency Virus AIDS = Acquired Immune Deficiency Syndrome * HIV = virus that causes AIDS.

18. HIV & AIDS Info: HIV is LYSOGENIC >42 mil. have died with HIV/AIDS 40,000 new infections found every year in U.S.; 50% in ages 25 or younger

19. Most don’t die from AIDS – they die from another disease the immune system can’t fight off. HIV attacks & weakens immune system (kills helper T-cells) - unable to fight off certain infections.

20. Bacteria Single-celled prokaryotes Living cells Many shapes and sizes

21. Structure of Bacteria 1. DNA (circular, not in a nucleus) 2. Cytoplasm 4. Cell wall 3. Cell membrane

22. http://www.sirinet.net/~jgjohnso/typicalbacteria.html

23. How do bacteria reproduce? 1. Binary fission –bacterium copies itself & divides into two asexual reproduction makes identical bacteria

24. http://www.anselm.edu/homepage /jpitocch/genbio/binfission.JPG

25. Fighting Bacterial Infections 1. Antibiotics - compounds that block growth & reproduction of bacteria If stop taking too soon, not all bacteria get destroyed

26. Antibiotic Resistance = remaining bacteria mutates & is unaffected by antibiotic 2. Vaccination 3. Sterilization – using high heat to kill bacteria