2/28/12
• What is a halophile?
• Key Term: archaea
3/1/12
• What compound makes up the cell wall of a
bacterium?
• Key terms: same as yesterday
Prokaryotes
• Domain Bacteria
• Domain Archaebacteria
Domain
Bacteria
Domain
Archaea
2007-2008
Common ancestor
Domain
Eukarya
Bacteria Structures
Bacteria Structures/Functions
Structure
Function
Flagella
Tail-like structure for movement
Pili
Projection of cell wall for sticking to
surfaces
Cell wall
Maintains shape of cell; protects the cell
Cell membrane
Regulates what leaves and enters the cell
DNA
Stores hereditary information
Ribosomes
Builds proetins
Prokaryote Structure
• Unicellular
– bacilli, cocci, spirilli
• Size
– 1/10 size of eukaryote cell
• 1 micron (1um)
• Internal structure
– no internal compartments
• no membrane-bound organelles
• only ribosomes
– circular, naked DNA
• not wrapped around proteins
prokaryote
cell
Genetic variation in bacteria
• Mutations
– bacteria can reproduce every 20 minutes
• binary fission
– error rate in copying DNA
• 1 in every 200 bacteria has a mutation
• Genetic recombination
– bacteria swap genes
• plasmids
– small supplemental
circles of DNA
Genetic Recombination
Type
Source of New genes
Entry method
Transformation
DNA in surroundings
Endocytosis
Transduction
Virus w/bacterial DNA
Viral mediated entry
Conjugation
Other bacteria
Pili bridge
http://www.phschool.com/science/biology_place/labbench/lab6/con
cepts1.html
http://highered.mcgrawhill.com/sites/0072556781/student_view0/chapter13/animation_quiz_2.
html
http://www.hhmi.org/biointeractive/animations/conjugation/conj_frames
.htm
Archaebacteria
• Extremophiles:
– Thermoacidophiles – love heat (up to 110’C) and
acidic environments; require sulfur; anaerobic ex:
Sulfolobus, Pyrodictium
– Halophiles –love environments with high salt
concentrations like the Great Salt Lake and the Dead
Sea; nearly all aerobic; all Gram-negative ex:
Halococcus
– Methanogens – anaerobic methane producers; use
carbon dioxide; live in soil, swamps, digestive tracts
ex: Methanococcus
Bacterial diversity
rods and spheres and spirals… Oh My!
Prokaryote Cell Wall Structure
Gram-positive bacteria
peptide side
chains
cell wall
peptidoglycan
plasma membrane
protein
That’s
peptidoglycan = polysaccharides + amino acid chains
important for
lipopolysaccharides = lipids + polysaccharides
your doctor
to know!
outer membrane of
Gram-negative bacteria
lipopolysaccharides
cell wall
outer
membrane
peptidoglycan
plasma
membrane
Bacteria live EVERYWHERE!
• Bacteria live in all ecosystems
– on plants & animals
– in plants & animals
– in the soil
– in depths of the oceans
– in extreme cold
– in extreme hot
– in extreme salt
– on the living
– on the dead
Prokaryotic metabolism
• How do bacteria acquire their energy &
nutrients?
– photoautotrophs
• photosynthetic bacteria
– chemoautotrophs
• oxidize inorganic compounds
– nitrogen, sulfur, hydrogen…
– heterotrophs
• live on plant & animal matter
• decomposers & pathogens
Variations in Cell Interior
cyanobacterium
(photosythetic) bacterium
aerobic bacterium
Bacteria as pathogens
Disease-causing microbes
plant diseases
wilts, fruit rot, blights
animal diseases
tooth decay, ulcers
anthrax, botulism
plague, leprosy, “flesheating” disease
STDs: gonorrhea,
chlamydia
typhoid, cholera
TB, pneumonia
lyme disease
Do you recognize…?
Bacteria as beneficial (& necessary)
• Life on Earth is dependent on bacteria
– decomposers
• recycling of nutrients from dead to living
– nitrogen fixation
• only organisms that can fix N from atmosphere
– needed for synthesis of proteins & nucleic acids
– plant root nodules
– help in digestion (E. coli)
• digest cellulose for herbivores
– cellulase enzyme
• produce vitamins K & B12 for humans
– produce foods & medicines
• from yogurt to insulin
Pathogenic Bacteria
Name of
bacteria
Can you
predict the
shape from
name?
Gram-Stain
(+ = purple,
= pink)
Shape
Notes