Viruses and Bacteria

1. Viruses and Bacteria

2. What do these diseases have in common? Mumps http://www.kcom.edu/faculty/chamberlain/Website/lectures/lecture/IMAGE/MUMPS.GIF Hepatitis B http://www.idph.state.il.us/images/hepatitisb.jpg Measles http://www.idph.state.il.us/images/measles.jpg Polio http://www.immune.org.nz/site_resources/Professionals/Diseases/Polio/Polio.jpg

3. It looks alive, acts alive… but it’s not alive! • Viruses are not living things. They differ from living things in several ways. • They need to be inside a living organism to reproduce themselves. • Outside the cell, they have no metabolism. • They do not have cell parts. (i.e. nucleus, mitochondria, etc.) • Most viruses are composed of only a nucleic acid (DNA or RNA) inside a protein capsule.

4. Virus Structures Protein capsid DNA (or RNA) Tube http://mrsec.wisc.edu/Edetc/technologist/thumbnails/Matt/Virus_diagram.jpg Tail Fiber http://www.humanillnesses.com/images/hdc_0001_0001_0_img0008.jpg http://www.aidsactioncoalition.org/images/hiv_virus.gif

5. Viral Reproduction • In order to reproduce: • A virus attaches to a host cell. • The virus injects the cell with its nucleic acid. • The viral nucleic acid commands the cell to make more viral protein and nucleic acid. • The cell then ruptures, releasing hundreds of new viruses. http://porpax.bio.miami.edu/~cmallery/150/gene/sf11x1virus.jpg

6. No, they aren’t from the 70’s. • Retroviruses. • These are viruses that store their genetic information as RNA. • Ex. HIV (Human Immunodeficiency Virus.) http://international.ucla.edu/cms/images/hiv_virus.jpg

7. How it works…… http://hiv.buffalo.edu/./images/hiv_virus_in_action.jpg

8. Kingdoms Eubacteria and Archaebacteria • Bacteria are living, unicellular prokaryotes. • Cover nearly every square centimeter of the Earth. • Are heterotrophs or autotrophs (most use chemosynthesis). • Types of Bacteria are classified based on their shape, type of cell wall, and movement. • Bacteria have three basic shapes: • Bacilli – rod-shaped • Cocci – spherical • Spirilla – spiral http://fig.cox.miami.edu/~cmallery/150/proceuc/c27x3proc_shapes.jpg

9. Structure of a Bacteria Cell membrane Cell wall DNA Ribosomes http://www.ou.edu/class/pheidole/General%20Bacteria.jpg

10. Eubacteria have peptidoglycan and certain specialized lipids in their cells walls that are not present in Archaebacteria. • Gram staining is used to differentiate types of Eubacteria. • Those having thick cell walls will absorb more of the dye and appear dark purple (Gram positive). • Those having thinner cell walls will absorb less of the dye and appear pink (Gram negative). http://bioweb.uwlax.edu/bio203/s2008/jaedike_alic/grainpositive.jpg http://www.asm.org/Division/c/photo/gc1.JPG

11. Bacteria Growth and Reproduction • Bacteria reproduce in 2 main ways: • Binary fission - bacteria grows to double its original size, copies its DNA and divides, producing 2 identical cells. • Conjugation - a hollow bridge is formed between 2 bacteria, genes are transferred from one cell to the other. • Creates genetic diversity within a population. • Spore formation - when conditions are unfavorable (lack of food, drought) a bacterium encloses its DNA and part of its cytoplasm in a spore. • When conditions are better, the spore will germinate, and the bacterium will continue to grow. http://porpax.bio.miami.edu/~cmallery/150/gene/sf9x3box.jpg http://www.emc.maricopa.edu/faculty/farabee/BIOBK/69091a.jpg

12. Dangers of Bacteria • Break down cells and tissues for food. • Ex. Tuberculosis (destroys lung tissue). • Release toxins (poisons) that travel through the body. • Ex. Streptococcus releases toxins into the blood stream causes strep throat and scarlet fever.

13. We’re not all bad…. • Bacteria are most widely known for causing diseases such as strep throat, tetanus, meningitis, and tuberculosis. • However, most bacteria are very useful: • E. coli helps us digest our food. • Many are important decomposers in our ecosystem. • Rhizobium provides plants with nitrogen. • A few bacteria are used to clean up small oil spills in the ocean.

14. Vaccinations • A weakened or killed form of the pathogen (virus/bacteria) is used to stimulate the production of antibodies. • However, viruses and bacteria have very high reproductive rates, which result in many mutations. • Thus, viruses and bacteria evolve quickly, often requiring a different vaccine every year. • Ex. Influenza vaccinations. http://www.biojobblog.com/vaccination%5B1%5D.JPG http://www.biojobblog.com/vaccination(5).jpg

15. There are two types of vaccines (immunities). • Active - a person is injected with the actual pathogen, immune cells make their own antibodies against the disease. • Immunity is permanent. • Passive - person is injected with antibodies that fight the disease • Immunity is temporary. http://www.iavi.org/viewpage.cfm?aid=1682

16. Antibiotics • Antibiotics block the growth and reproduction of bacteria. • Used to treat bacterial infections.

17. Diseases such as Scrapie (in sheep) and Mad Cow Disease are not caused by bacteria or viruses. What could cause them?

18. Prions • Contain only protein. • Cause disease by forming protein clumps which then induce normal proteins to become Prions. • The build up eventually damages nerve tissue.