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Notes: Bacteria.

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Presentation on theme: "Notes: Bacteria."— Presentation transcript:

1 Notes: Bacteria

2 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.

3 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

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

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

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

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

8 Name this bacterium streptococcus

9 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

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

11 1. Binary Fission Asexual Produces identical cells thru mitosis

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

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

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

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

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

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

18 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

19 1

20 2

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22 4

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

24 Oswald Avery 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

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

26 Controlling Bacteria Vaccines Antibiotics Sterilization Disinfectants,
Food Processing & Storage


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