Notes: Bacteria

General Characteristics Microscopic, Exist everywhere Unicellular Prokaryotic (no nucleus or membrane bound organelles) E. coli is a typical bacterium that lives in the human intestines.

Kingdom Archaebacteria Found in extreme environments Do not have peptidoglycan in cell walls Instead have unique compounds in cell wall depending on species. Examples: Methanogens - in oxygen-free environments, like animals’ intestines - symbiosis Halophiles – in concentrated saltwater Thermoacidophiles – in hot, acidic waters of sulfur springs

Kingdom Eubacteria Ecologically diverse Have peptidoglycan in cell walls. Heterotrophs - Decomposers Parasites Autotrophs - Cyanobacteria: common in ponds, streams, and moist areas of land.

General Bacteria picture Peptidoglycan Cell Wall Cell membrane Ribosome Pili DNA Flagellum

Basic Structure No membrane-bound organelles Small ribosomes DNA - single circular chromosome Cell wall (peptidoglycan) Can be classified by shape & metabolism

Cell Shapes & Arrangements Spheres: cocci (-us) Rods: bacilli (-us) Spiral: spirilla (-um) Pairs: Diplo- Cluster: Staphylo- Chain: Strepto-

Name this bacterium streptococcus

Metabolism Obligate aerobes require oxygen for cellular respiration Obligate anaerobes no oxygen, produce energy thru glycolysis/fermentation Facultative anaerobes can survive with or w/out oxygen

Growth & Reproduction Some divide every 20 min. Pop. held in check by food availability & wastes produced

1. Binary Fission Asexual Produces identical cells thru mitosis

2. Conjugation Sexual Exchange genetic info new gene combos & bacteria diversity

Endospore Thick internal wall around DNA Unfavorable growth conditions – heat, dry, no nutrients Can remain dormant – years

Ecological Importance Producers Decomposers – recycle nutrients Nitrogen fixers – ex. Soybeans Sewage treatment

Human Importance Foods: Swiss cheese, pickles, yogurt Medicines: antibiotics Crops: nitrogen fixation, control pests Digestion: E.coli

Antibiotics Kill bacteria by interfering w/metabolism Ex: penicillin, streptomycin, tetracycline, amoxicillin, zithromax, omnicef Staphylococcus aureus & penicillium mold

How do bacteria make people sick? 1. Produce toxins that “poison” host cells 2. Bacterial cells crowd out healthy host cells.

Griffith’s Transformation Experiment Pneumonia bacteria experiments 1928 – Fredrick Griffith Had isolated 2 strains of bacteria Smooth colonies – caused disease Rough-edges colonies – no disease

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Summary of Griffith’s Transformation Mixing Rcells + heat-killed Scells causes a factor to transform the Rcells into Scells

Oswald Avery - 1944 Extracted “juice” from heat-killed S bacteria + enzymes to destroy proteins, lipids, carbs, & RNA  transformation still occurred Extract + enzymes to destroy above & DNA  NO transformation DNA = Factor causing transformation

Diseases Louis Pasteur Few kinds release toxins or damage cells Ex: tuberculosis, botulism, strep throat & scarlet fever, tetanus, pneumonia, anthrax, meningitis

Controlling Bacteria Vaccines Antibiotics Sterilization Disinfectants, Food Processing & Storage