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Bacteria
Prokaryotes
Lack nucleus and membrane bound organelles
Evolving on Earth for last 2.5 billion years
Exist in variety of environments
First organisms
How are bacteria classified?
• Previously only based on structure
& physiology (Kingdom Monera)
• Currently rRNA sequences used to
distinguish two different
kingdoms
Two Kingdoms for bacteria
Kingdom Archaebacteria – found in
extreme environments
Kingdom Eubacteria- bacteria you come in
contact with every day
Kingdom Archaebacteria
Found in extreme
environments
Kingdom Archaebacteria
Methanogens
Anaerobic (Can’t live in O2)
Convert H2 and CO2 into Methane
Swamps, sewage, guts of cows, termites
Extreme Halophiles-salt loving
salt beds
Thermoacidophiles-live in
hot, acidic environments
Hydrothermal vents, hot springs
Kingdom Eubacteria
Three Shapes
Bacilli
Cocci
Spirilla
b Structure of Bacteria
Capsule
Cell Wall
Cell Membrane
Cytoplasm
Capsules
Ribosomes
Pili
DNA
Flagella
Reproduction &
Genetic Recombination
Reproduces by binary fission
Transformation-DNA from external environment
Conjugation-Transfer of genetic info between 2
bacteria cells via the plasmid
Transduction-virus carries DNA from one host
bacterium to its next host
Useful Bacteria
E. coli- lives in human intestinal tract
Aids in break down of food
500-1000 different types of bacteria in your intestinal
tract
Food production- Yogurt, buttermilk, sour cream
Streptococcus sanfranciscus
Lactobacillus acidophilus
Environmental Cleanup-oil spills
Antibiotic production-Streptomycin
How do bacteria make you sick?
Produce exotoxins – secreted proteins causes dehydration
Ex. Most bacterial infections
Some release endotoxins when they die as
cell wall breaks down
Example typhoid fever and food poisoning
Bacteria and Disease
Pathology is the study of disease
Necrotizing fasciitis
Staphylococcus infection
Antibiotics
Antibiotics are drugs that combat bacteria by
interfering with functions
Penicillin-interferes w/ cell wall synthesis
Tetracylcine-interferes with protein synthesis
Erythromyocine-prevents protein synthesis @ribosome
Antibiotic Resistance-increase with increased use
of antibiotics
Steadily increasing since 1940’s
Developed from some bacteria and molds, also
chemically synthesized
Phylum Cyanobacteria
Oldest bacteria
Photosynthetic
Phylum Spirochetes
Spiral shaped
Aerobic bacteria = needs O2
Ex. Syphilis, Lyme Disease
Phylum Gram-Positive Bacteria
Source of some antibiotics
Pathogenic- Ex. Strep throat
Phylum Proteobacteria
Escherichia coli (E. coli)
Largest & Most
diverse group
Some bacteria can
convert chemicals in
minerals into energy
Some live in human
intestinal tract