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Defense against infections disease

Defense against infections disease. Ms. Fargo With some slides courtesy of Stephen Taylor. Bacteria Prokaryotes (no real nucleus) Divide by binary fission. Can cause: Food poisoning (e.g. Salmonella) Ear and eye infections Cholera, diarrhea.

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Defense against infections disease

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  1. Defense against infections disease Ms. Fargo With some slides courtesy of Stephen Taylor

  2. Bacteria • Prokaryotes (no real nucleus) • Divide by binary fission • Can cause: • Food poisoning (e.g. Salmonella) • Ear and eye infections • Cholera, diarrhea http://en.wikipedia.org/wiki/File:Ericson_Type_II_Conjunctivitis.JPG

  3. Viruses • Acellular(non-living?) • Need a ‘host’ cell to carry out functions of life, including reproduction • Can have DNA or RNA • Mutate, evolve and recombine quickly • Cause: • Flu, HIV/AIDS, smallpox, measles, common cold, herpes, ebola The 1918 flu epidemic killed between 50 and 130 million people. http://en.wikipedia.org/wiki/1918_flu_pandemic

  4. Fungi • Eukaryotes, reproduce with spores • Cause: • Athlete’s foot, mould, ringworm • Allergic reactions and respiratory problems Image from: http://en.wikipedia.org/wiki/Athlete's_foot

  5. Protozoa • Simple parasites • Cause: • Malaria • Leishmaniasis • Toxoplasmosis Leishmaniasis image from: http://en.wikipedia.org/wiki/Leishmaniasis

  6. Bactericidal vs. Bacteriostatic • Bactericidal or fungicdal agents • Kill microbes • Bacteriostatic and fungistatic • Stop further growth • Don’t kill existing cells • It is thought that because the growth of the pathogen is stopped, the body’s immune system will be able to kill it.

  7. Antibiotics • Can be selectively toxic by targeting such features as the • Bacterial cell wall • 70 S ribosomes • This is the size of prokaryotic ribosomes • Enzymes that are specific to bacteria. • In this way, the human eukaryotic cells are unaffected.

  8. Antibiotics are ineffective against viruses! Over-use of antibiotics is accelerating the evolution of more harmful bacteria. We are running out of antibiotics that work and are selecting for diseases such as MRSA. http://www.youtube.com/watch?v=RedO6rLNQ2o • Antibiotics are designed to disrupt structures or metabolic pathways in bacteria and fungi: • cell walls and membranes • DNA synthesis (replication) • RNA polymerase • Translation • These do not exist or are very different in viruses, so the antibiotic will have no effect. Bacterial drug resisance, from Wiley Essential Biochemistry. Find out more here: http://www.wiley.com/college/pratt/0471393878/student/activities/bacterial_drug_resistance/index.html

  9. Antibiotics are ineffective against viruses! • Analyse the graph below. Over time, outline what has happened to: • The number of new approved antibiotics • The diversity of new approved antibiotics • Suggest reasons for your answers. Use the graph to write your own DBQ practice questions. Chlamydia trachomatis bacteria. Are you ready for the end of antibiotics? Guardian: http://gu.com/p/2jxgj The scariest graph you’ll ever see. Read the article by Maryn McKenna: http://www.wired.com/wiredscience/2011/02/not-many-antibiotics/

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