Prokaryotes and Metabolic Diversity

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(No Transcript)
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Anthrax Bacillus anthracis
Cutaneous anthrax
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Microbial Diversity

• Chapt. 27 Prokaryotes and the Origins of
  Metabolic Diversity
• Chapt. 28 The Origins of Eukaryotic Diversity

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What are microbes?

• Single-celled organisms and some non-cellular
  parasites

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Kinds of microbes

• Non-cellular, parasitic molecules
• Viruses
• Viroids
• Prions
• Prokaryotes
• Domain Bacteria
• Domain Archaea
• Eukaryotes
• Several Kingdoms in Domain Eukarya

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Nonliving parasitic molecules

• Viruses
• Single or double stranded RNA or DNA with a
  protein coat
• Common cold, Ebola, HIV

HIV
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Nonliving parasitic molecules

• Viruses
• Single or double stranded RNA or DNA with a
  protein coat
• Common cold, Ebola, HIV

Viroids Short, single strand of RNA w/o protein
coat Primarily infect plants
Prions Protein particles w/o genetic
material Kuru, mad cow, chronic wasting disease
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Kinds of microbes

• Non-cellular, parasitic molecules
• Viruses
• Viroids
• Prions
• Prokaryotes
• Domain Bacteria
• Domain Archaea
• Eukaryotes
• Several Kingdoms in Domain Eukarya

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Carl Woeses 3 Domains of Life
Based primarily on genetic sequence datae.g.,
small subunit ribosomal RNA present in all
organisms
See Fig. 27.12
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Carl Woeses 3 Domains of Life
Prokaryotes
Eukaryotes
NOTE Microbes and Prokaryotes are not
taxonomic categories
See Fig. 27.12
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Carl Woeses 3 Domains of Life
Prokaryotes
Eukaryotes
NOTE Eukarya Archaea are more closely related
than either is to Bacteria
See Fig. 27.12
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Carl Woeses 3 Domains of Life
Prokaryotes
Eukaryotes
Even so, Archaea Bacteria share more structural
functional properties than either does with
Eukarya
See Fig. 27.12
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Microbes are microscopic, but very diverse
extremely abundant
Bacteria on the tip of a pin
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Relative sizes of microbes
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Prokaryotes

• Domains Bacteria Archaea
• Simple cells with no nucleus or
  membrane-bound organelles

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Prokaryotes

• Domains Bacteria Archaea
• Simple cells with no nucleus or
  membrane-bound organelles
• First organisms on Earth at least 3 billion
  years ago

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The oldest known fossilsCyanobacteria gt 3
billion years old
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Prokaryotes

• Domains Bacteria Archaea
• Simple cells with no nucleus or
  membrane-bound organelles
• First organisms on Earth at least 3 billion
  years ago
• Distributed globally including many
  extremophiles

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Extreme ThermophilesHeat-loving Archaea
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Extreme HalophilesSalt-loving Archaea
pink color due to halophiles
Australian Salt Lake
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MethanogensMethane-generating Archaea

• Occur in oxygen-free habitats
• E.g., swamp mud, guts of ruminant animals

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Ice Bacteria Archaea
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Cave Bacteria

• Sometimes reaching acidity of pH 0.5

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Prokaryotes

• Domains Bacteria Archaea
• Simple cells with no nucleus or organelles
• First organisms on Earth at least 3 billion
  years ago
• Distributed globally including many
  extremophiles
• Nutrition autotrophs heterotrophs

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Prokaryote Nutrition
All organisms require a source of energy carbon
Autotrophs can obtain all their C from CO2
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Prokaryote Nutrition
All organisms require a source of energy carbon
Heterotrophs require at least one organic
nutrient, e.g., glucose
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Prokaryote Nutrition
All organisms require a source of energy carbon
Phototrophs obtain their energy from the sun
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Prokaryote Nutrition
All organisms require a source of energy carbon
Chemotrophs obtain their energy from chemical
compounds
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Bacteria

• Structure

Systematic / phylogenetic relationships among
bacteria are based on genetic data, but
structural properties are indispensable for
identifying them
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Bacteria

• Structure

Cell wall unique, peptidoglycan Peptidoglyca
n - structural polysaccharides (sugars)
cross-linked by peptides (chains of amino
acids)
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Two biochemical groups of bacteria
outer membrane
peptidoglycan
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Two biochemical groups of bacteria
outer membrane
peptidoglycan
will stain
will not stain
Gram positive bacteria
Gram negative bacteria
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Gram stainDistinguishes different cell wall types

• Gram positive Staphylococcus aureus
• Gram negative Escherichia coli

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3 common bacterial shapes
Cocci- spheres
Bacilli- rods
Spirilli- spirals
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Bacteria

• Structure
• Cell wall unique, peptidoglycan
• Capsules or slime layer

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E.g., slime layer allows bacteria to cling to
tooth enamel or other substrates
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Bacteria

• Structure
• Cell wall unique, peptidoglycan
• Capsules or slime layer
• Pili Flagella

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Pili (singular pilus)

• Protein filaments that attach bacteria to other
  cells substrates

pili
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Some prokaryotes have flagella(singular
flagellum)

• Used for locomotion

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Base of a bacterial flagellum
the only known wheel in nature
50 nm
Fig. 27.6
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What is taxis?
Motility allows some bacteria to move towards or
away from stimuli
Phototaxis
Chemotaxis
Magnetotaxis
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Bacteria

• Structure
• Cell wall unique, peptidoglycan
• Capsules or slime layer
• Pili Flagella
• Circular DNA molecule plasmids

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Bacteria

• Reproduction
• Asexual, through binary fission

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Binary fission

• Daughter cells are identical copies

Chromosome
Plasma membrane
(3)
(1)
(2)
(4)
(5)
(6)
Neither mitosis nor meiosis occurs in prokaryotes
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Binary fission

• E. coli

DNA
cell wall
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Bacteria

• Reproduction
• Asexual, through binary fission
• No true sexual reproduction, since neither
• mitosis nor meiosis exist in prokaryotes

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Bacteria

• Reproduction
• Asexual, through binary fission
• No true sexual reproduction, since neither
• mitosis nor meiosis exist in prokaryotes
• Horizontal transfer of genetic material
• Transformation

Uptake of genetic material from the environment
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Bacteria

• Reproduction
• Asexual, through binary fission
• No true sexual reproduction, since neither
• mitosis nor meiosis exist in prokaryotes
• Horizontal transfer of genetic material
• Transformation
• Transduction

Transfer of genetic material between prokaryotes
by viruses
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Bacteria

• Reproduction
• Asexual, through binary fission
• No true sexual reproduction, since neither
• mitosis nor meiosis exist in prokaryotes
• Horizontal transfer of genetic material
• Transformation
• Transduction
• Conjugation

Direct transfer of genetic material from one
prokaryote to another
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Conjugation in E. coli
Sex pilus connects cells and draws them
together Conjugation tube then forms
Sex pilus
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Bacteria

• Surviving harsh conditions
• Endospore forms inside a bacterium and
• then persists through inhospitable conditions

endospore
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Louis Pasteurs observations (1860s) on
decomposition disproved spontaneous generation
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Louis Pasteurs observations (1860s) on
decomposition disproved spontaneous generation
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Louis Pasteurs observations (1860s) on
decomposition disproved spontaneous generation
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Photosynthesis
Especially common in the cyanobacteria
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Photosynthesis
Especially common in the cyanobacteria
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
Symbiosis Mutualism
Rhizobium in the roots of a soybean plant
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
Symbiosis Mutualism, commensalism
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Bacteria Impacts on other organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
Symbiosis Mutualism, commensalism,
parasitism
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E.g., Clostridium tetani, the species that causes
tetanus by producing a toxin that interferes with
nerve impulses and causes muscles to spasm
Bacteria are often agents of disease by producing
toxins
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Robert Koch (late 1800s) was the first person to
link diseases to specific species of bacteria
Bacteria are often agents of disease by producing
toxins
The Germ Theory revolutionized medicine in the
early 20th century
Kochs Postulates guide the identification of
disease agents
1. Find the same pathogen in each victim
2. Isolate the pathogen grow it in pure culture
3. Induce the disease in a healthy individual
from culture
4. Isolate the same pathogen after disease occurs
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Bacteria Impacts on other Organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
Symbiosis Mutualism, commensalism,
parasitism
What type of symbiont is Escherichia coli?
Normal strains provide K B-complex vitamins
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Bacteria Impacts on other Organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
Symbiosis Mutualism, commensalism,
parasitism
What type of symbiont is Escherichia coli?
Some infectious strains cause disease
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Bacteria Impacts on other Organisms, including
Human Society

• Decomposition

Photosynthesis
N-fixation
Symbiosis Mutualism, commensalism,
parasitism
Bioremediation
Oil spills, mine tailings, heavy metal dumps, etc.
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Archaea

• Structure
• Several basic biochemical differences
  distinguish them from Bacteria
• E.g., No peptidoglycan in their cell walls

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Archaea

• No known pathogens!

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Archaea
Many are extremophiles
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Archaea
Even so, archaea are not restricted to extreme
habitats
Archaea account for 20-30 of marine microbial
cells