Download presentation
Presentation is loading. Please wait.
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
21
3
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
Similar presentations
© 2024 SlidePlayer.com Inc.
All rights reserved.