Download prokaryote cell

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
Bacteria Structures/Functions
Structure
Flagella
Pili
Cell wall
Cell membrane
DNA
Ribosomes
Function
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
Bacterial diversity
rods and spheres and spirals… Oh My!
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
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
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
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
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
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
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
Comparison of prokaryotes and
eukaryotes…
• Describe three ways in which prokaryotes are
similar to eukaryotes.
• Explain the size difference in prokaryotes and
eukaryotes.
• Prokaryotes and eukaryotes have three
structures in common. Both have cell
membranes that regulate what leaves and
enters the cell. Ribosomes, which make
proteins, are found in both types of cells. The
cytoplasm, a fluid filled with ions and water,
surrounds the internal structures in
prokaryotes and eukaryotes. DNA is present
in both cells however, in eukaryotes it is
contained in a nucleus.
• Eukaryotes are 10 times larger than
prokaryotic cells. They have many internal
compartments (organelles) that prokaryotes
do not. The Theory of Endosymbiosis suggests
that larger cells “ate” bacteria cells and didn’t
digest them so they became larger.
Pathogenic Bacteria
Name of
bacteria
Can you
predict the
shape from
name?
Gram-Stain
(+ = purple,
= pink)
Shape
Notes