Chapter 27: Bacteria and Archaea
Prokaryotes and the Origin of Metabolic Diversity
I. General Structure of a Prokaryote
*All reproduce asexually
via binary fission
Sticky protective layer; adhesion and protection
Capsule from host defenses
glucose + amino acid cross
Cell Wall Peptidoglycan links
1. Gram + Thick peptidoglycan wall; stain purple
Peptidoglycan imbedded in an outer and inner
2. Gram membrane: more pathogenic; endotoxins in
membrane; antibiotic resistance; stain red
Cell Membrane Semipermeable; may have extra folds to
accommodate respiratory and
Nucleoid
photosynthetic enzymes
Region
Circular DNA; not membrane bound;
not associated with protein
Ribosomes
Different protein and smaller than eukaryotic
Pili
ribosomes; antibiotics
Adhesion to substrate or other bacteria; transfer
plasmid during conjugation
Plasmid Small circular transferable DNA that contain
extra genes; antibiotic resistance; metabolic
enzymes; replicate independently
Basal Apparatus
Rotates flagella; powered by diffusion
Flagella
of H+ ions
Rigid “propeller like”(eukaryote flagella flexible); used in chemotaxis
II. Prokaryote Taxonomy
The Domain Distinctions
Characteristic
1. Nuclear Envelope
(Prokarotes)
(Prokarotes)
1. Absent
1. Absent
1. Present
2. Absent
2. Absent
2. Present
3. Present
3. Absent
3. Absent
4. Initiator Amino Acid
4. Formyl- methionine
4. Methionine
4. Methionine
5. Introns
5. Rare
5. Some genes
5. Most genes
2. Membrane bound
organelles
3. Peptidoglycan
6. Antibiotic response
6. Growth inhibited
6. No inhibition
7. Histones
7. Absent
7. Present
7. Present
8. Chromosome
8. Circular
8. Circular
8. Linear
6. No inhibition
(ribosome)
Gram Negative
chemoautotrophs
photoautotrophs
chemoheterotrophs
aerobic and
anaerobic
Obligate
parasites;
Corkscrew
free living
lack
and
peptidoglycan pathogenic
Why so many prokaryotes?
1. Rapid reproduction and
mutation
Blue-green
bacteria
Methanogensproduce
Thermophiles
release O2
methane
chemosyntheti
during
waste;
photosynthesi anaerobic sulfur
metabolism
s
Gram Positive
Halophiles
chemoautotrophs
photoautotrophs
chemoheterotrophs
aerobic and
anaerobic
salt loving;
photosynthetic
bacteriorhodopsin
2. Genetic recombination
-transformation: uptake of foreign DNA
All are forms
Extremophiles of horizontal
gene transfer
-conjugation: DNA (as plasmids) transferred between two temporarily joined cells via pili
-transduction: bacteriophages carry prokaryotic genes from one host cell to another
III. The Metabolic Diversity of Prokaryotes
A. Energy and Carbon Requirements
All organism must have:
Energy Source
Carbon Source
Origin of the energy to "excite”
electrons to make ATP
Origin of carbon required to
build organic molecules
Possibilities
1. Electrons “excited”
by light
1. Carbon from CO2 (inorganic origin)
Name: Autotrophs
Name: Photo
2. Electrons extracted from
“high energy molecules”
Name: Chemo
2. Carbon from pre-made
organic compounds
(lipids, COH’s, protein)
Name: Heterotrophs
B. Metabolism Possibilities
Metabolism
Possibilities
PhotoAutotroph
PhotoHeterotroph
Electron Source
Carbon Source
Examples
Light
CO2
Plants, Algae,
Cyanobacteria
COH’s
Light
Some Prokaryotes
Lipids
Proteins
ChemoAutotrophs
Inorganic Chemicals
(Fe++, S, NH3, NO2-, H2)
CO2
Thermophiles,
Some decomposers
(Ammonifing, nitrifying,
denitrifying)
ChemoHeterotrophs
Organic Carbon
(COH’s, Protein, Lipids)
Organic Carbon
(COH’s, Protein, Lipids)
Most Prokaryotes,
Protist, Fungi
Animals
C. Oxygen Requirements:
Oxygen is the most abundant and most effective
electron acceptor to make ATP with an electron
transport chain
1. Obligate Aerobes: Organism uses O2 as final electron acceptor
e-
ATP
Electron
Transport
Chain
H+
O2
H2O
Obligate aerobes must have O2 in order to make enough ATP for survival
2. Obligate Anaerobes:
a. Organism uses molecules other than O2 as final electron acceptor.
b. Oxygen is toxic since it binds the electrons before ATP can be made
e-
ATP
Electron
Transport
Chain
Without Oxygen Present
H+
S2
H2S
2. Obligate Anaerobes:
a. Organism uses molecules other than O2 as final electron acceptor.
b. Oxygen is toxic since it binds the electrons before ATP can be made
e-
O2
No ATP made
Oxygen Present
Electron
Transport
H+
S2
Chain
Some may live exclusively by fermentation to make ATP
Glucose
Fermentation
Waste Products
+ 2ATP
1. Ethyl Alcohol + CO2
Anaerobic decomposition has
an acid pH due to acidic waste
products
2. Lactic Acid
3. Acetic Acid (vinegar)
3. Facultative Aerobes/Anaerobes
1. May contain both aerobic and anaerobic ETC and rely on fermentation to
make ATP
2. Some “harmless” bacteria may become pathogenic depending on
the type of respiration is used determined by the environment.
Example: E. coli
D. Nitrogen Requirements:
Nitrogen is needed to build proteins and
nucleic acids. Nitrogen can also be used as
an “excited” electron source.
1. Ammonification Bacteria
Protein
Ammonia(NH3) + (e- to make ATP)
Both Aerobic or Anaerobic
2. Nitrification Bacteria
NH3
Some species
Requires O2
Nitrite (NO2) + (e- to make ATP)
Nitrite (NO2)
Nitrate (NO3) + (e- to make ATP)
Some species
Some soil
bacteria, legume
nodule bacteria
3. Nitrogen Fixation
Atmospheric Nitrogen (N2)
Nitrates (NO3)
blue-green
bacteria
4. Denitrification
Nitrate (NO3)
Nitrite (NO2)
NH3
Anaerobic denitrifying bacteria
Atmospheric Nitrogen (N2)
IV. Prokaryote Niches
A. Recyclers
1. Global cycles
Carbon, Oxygen, Nitrogen, Sulfur & Water
2. Interactions all involve decomposition
B. Symbiotic relationships
1. Parasitism: cause disease <1%
a. Many opportunistic
b. Secrete exotoxins or membrane bound endotoxins
2. Mutualistic
a. Digestion (termites, herbivores) & us (Vit K, B12, thiamin, riboflavin)
b. Photosynthesis (Cyanobacteria in lichens)
c. Bioluminescence (deep sea fish)
d. Nitrogen fixers (legumes)
C. Industrial Processes
1. Sewage/ waste treatment/bioremediation
2. Food Products: cheese, yogurt, vinegar, butter
3. Chemicals : acetone, alcohols
4. Pharmaceuticals: antibiotics, insulin, HGH (genetic engineered)
Bacteria Cell Wall Types
Gram +
Gram -
Slide 3
The Extra Duties of a Prokaryote Cell Membrane
Aerobic Bacteria
Note folds in membrane to
accommodate electron
transport chains (cristae?)
Photosynthetic Bacteria
Note folds in membranes to
accommodate chlorophyll
(thylakoids?)
Slide 3
The Multiple Uses of the Pili
Pili used for adhesion
A pilus used in conjugation
Slide 3
The Basal Apparatus: The Motor of the Flagella
Slide 3
Bacteria Flagella
Slide 3
Structure of
Peptidoglycan
Slide 3
Exterme
Thermophiles
Hot Springs
Sulfur
Metabolism
Slide 5
Gloeocapsa
Nosctoc
Calothrix
Fischerella
Cyanobacteria
Slide 5
Extreme Halophiles in Salt Ponds
Note: The color due to bacteriorhodopsin
Slide 5
What do these picture have to do with methanogens?
Slide 5
Proteobacteria
Myxobacteria
Rhisobium
Chromatium
Note Yellow Sulfur globules
H. pylori
B. bacteriophorus
Slide 5
An Animal Infected with Chlamydia
Chlamydias
Animal
Cell
Chlamydias
Slide 5
Spirochetes
Leptospira
Lyme Disease
B. burgdorferi
Slide 5
Many Mycoplasmas
on a human
fibroblast cell
Streptomyoces
Slide 5
Fermentation: Anaerobic Respiration
Without O2 all that is left is NADH, Pyruvate, and
Glucose with nowhere to go.
C6H12O6
ATP
NADH
H
Pyruvate
Mitochondria:
Oxidative
Phosphorylation
With
O2O2
ATP
NAD
NAD
NAD
Types of Fermentation
Bucket O’ NADA
1. Lactic Acid
1. NADH (energy rich) can be used to
convert pyruvate into another molecule
Lactic Acid Fermentation
(Muscle cells, Bacteria)
2. Fermentation allows NADH to
recycle to NAD in order to continue
to make ATP with out oxygen
2. Ethyl Acohol + CO2
Alcoholic Fermentation
(Bacteria, Yeasts)
3. Acetic Acid (vinegar) + CO2
(Bacteria)
Why Cells Do “Fermentation”
Slide 10
3. ATP can still be made as long as
the pyruvate is “going somewhere”
PILUS USED IN CONJUGATION
SLIDE 6
T
R
A
N
S
D
U
C
T
I
O
N
SLIDE 6
BINARY FISSION
Literally translates to “division in half ”
Slide 3
MUTUALISTIC BACTERIA
HUMAN GUT
BACTERIA
LICHEN
TERMITE GUT BACTERIA
CLOVER NODULES WHERE
NITROGEN FIXATION OCCURS
BIOLUMINESCENT BACTERIA
MUTUALISTS
FLASHLIGHT
FISH
Let’s watch it in action!
SLIDE 14
BOBTAIL SQUID
The Nitrogen Cycle: Nitrogen Required for Making Proteins
(N2)
Lightning
Nitrogen in atmosphere
(N2)
Animals
Denitrification
Plants
Food Chains
Waste
Death
Nitrogen-Fixing
bacteria in root
nodules of legumes
Bacteria soil
Nitrogen
Fixing
Denitrifying
Bacteria
Assimilation
Decomposers
Nitrates
(bacteria and
(NO3)
fungi)
Nitrification
Ammonification
Nitrifying
Ammonia Ammonium
(NH3)
(NH4+)
Bacteria
Nitrites
(NO2)
Ammonifying Bacteria Nitrifying Bacteria
SLIDE 12
Human Impact:1. Fertilizers
2. Sewage
Eutrophication: Overgrowth in lakes