Bacteria and Disease• A pathogen is a disease-causing agent.• Bacteria can damage the tissues of the affected organism directly or release toxins that harm the body.
Antibiotics• Compounds that block the growth and reproduction of bacteria.• Examples: penicillin & tetracycline
Common Diseases Caused byBacteriaDisease Pathogen PreventionTooth decay Streptococcus mutans Regular dental hygieneLyme disease Borrelia burgdorferi Protection from tick bitesTetanus Clostridium tetani Current tetanus vaccinationTuberculosis Mycobacterium tuberculosis VaccinationSalmonella food poisoning Salmonella enteritidis Proper food-handling practicesPneumonia Streptococcus pneumoniae Maintaining good healthCholera Vibrio cholerae Clean water supplies
Controlling Bacteria• Sterilization – destroys bacteria by subjecting them either to great heat or chemical action.• Disinfectants are chemical solutions that kill bacteria.
Controlling Bacteria• Food is refrigerated because bacteria grow slower at low temperatures.• Food can be sterilized by cooking at high temperatures.
Helpful Bacteria:Nitrogen fixation(Nitrogen Cycle) convert nitrogen gas into nitrates in the soil used by plants
Helpful BacteriaSaprobes: break down dead organic matter (decomposers)Food flavorings: produced by fermentation vinegar, yogurt, cheese, sour cream, pickles, sauerkraut
Antibiotic production:some bacteria produce antibioticsthat will kill other forms ofbacteriaBioremediation – help clean-up oil spillsWorks in Landfills to break downwastes (including some hazardouswastes)Waste- water treatment plants
Helpful Bacteria• Provide Vitamin K (E coli)- clots blood & keeps bones strong• Keep invading bacteria, viruses, & yeast in check.• Make Lactase-enzyme needed to break down dairy products
Bacteria Reproduction• Binary fission – asexual reproduction. The prokaryote replicates DNA and divides in half. (Mitosis)
• Conjugation – sexual reproduction. A hollow bridge forms between two cells and genes move from one cell to another. (Increases diversity.)