defense against infections disease
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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. - PowerPoint PPT PresentationTRANSCRIPT
Defense against infections disease
Ms. FargoWith some slides courtesy of Stephen Taylor
Assessment Statements Obj.
6.3.1 Define pathogen. 1
6.3.2 Explain why antibiotics are effective against bacteria but not viruses. 3
6.3.3 Outline the role of skin and mucous membranes in defense against pathogens. 2
6.3.4 Outline how phagocytic leucocytes ingest pathogens in the blood and body tissues. 2
6.3.5 Distinguish between antibodies and antigens. 2
6.3.6 Explain antibody production. 3
6.3.7 Outline the effects of HIV on the immune system. 2
6.3.8 Discuss the cause, transmission and social implications of AIDS. 3
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
The 1918 flu epidemic killed between 50 and 130 million people. http://en.wikipedia.org/wiki/1918_flu_pandemic
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
Fungi• Eukaryotes, reproduce with spores
Cause: • Athlete’s foot, mould, ringworm• Allergic reactions and respiratory
problemsImage from: http://en.wikipedia.org/wiki/Athlete's_foot
Protozoa• Simple parasites
Cause:• Malaria• Leishmaniasis• Toxoplasmosis
Leishmaniasis image from: http://en.wikipedia.org/wiki/Leishmaniasis
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.
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.
Antibiotics are ineffective against viruses!
http://www.youtube.com/watch?v=RedO6rLNQ2o
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.
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
Antibiotics are ineffective against viruses!
Chlamydia trachomatis bacteria. Are you ready for the end of antibiotics? Guardian: http://gu.com/p/2jxgj
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.
The scariest graph you’ll ever see. Read the article by Maryn McKenna:http://www.wired.com/wiredscience/2011/02/not-many-antibiotics/
