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Intro to Prokaryotes
Lecture 1
Spring 2014
Meet the Prokaryotes
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Meet the Prokaryotes
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Meet the Prokaryotes
Why study prokaryotes?
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Deep Time
Fig. 25.7
When did Prokaryotes evolve?
Stromatolites – rocklike structures
of bacteria and sediment
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Fossilized stromatolite (above) and living
stromatolite (below)
Deep Time
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• How did early
prokaryotes
produce ATP?
• Evolution of
electron transport
systems ~ 3 bya
• Development of
atmospheric oxygen
~ 2.7 bya
Fig. 25.7
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Deep Time
• Evolution of eukaryotes~ 2.1 bya
Fig. 25.8
The New Tree of Life
Phylogeny - the evolutionary
history of a species or group of
related species
Taxonomy
• Ordered division of organisms
into categories
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The New Tree of Life
Prokaryotes
Eukaryotes
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The New Tree of Life
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Fig. 26.21
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Review
1. Draw an animal cell. Label structures
w/name and function
2. Make a list of the differences between
plant and animal cells
3. Make a list of the differences between
prokaryotes and eukaryotes
Eukaryotes: Animal Cells
Animal cell structures:
• Plasma membrane
• Nucleus
• Cytosol
• Ribosomes
• Endoplasmic reticulum
• Golgi apparatus
• Mitochondria
• Cytoskeleton
• Vacuoles
• Peroxisome
Not typically found in plants:
• Centrosome
• Lysosomes
• Flagella
See Fig. 6.9 –Animal cell
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Eukaryotes: Plant Cells
Plant cell structures:
• Plasma membrane
• Nucleus
• Cytosol
• Ribosomes
• Endoplasmic reticulum
• Golgi apparatus
• Mitochondria
• Cytoskeleton
• Peroxisome
Not found in animals:
• Cell Wall w/plasmodesmata
• Plastids (Chloroplasts,
Amyloplasts, Chromoplasts)
• Central vacuole
Fig. 4.6 –Animal cell
See Fig. 6.9 – Plant cell
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Prokaryotes
Bacteria
• Cannot grow above 100˚C
Archaea
• Extremophiles
– thermophiles
– halophiles
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Prokaryotes
Prokaryotes: Domain Bacteria & Archaea
• Unicellular
• Colonial or solitary
• Small
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Structure: Shapes
Prokaryotes can be
described by shape
• coccus, bacillus,
spirillum
Colonies can be
described by how
cells are
aggregated
• strepto = in chains
– e.g., streptobacilli
• staphylo = in clusters
– e.g., staphylococci
(spirillum)
Fig. 27.2
Structure: Cell Walls
Function of cell walls?
Eukaryotes
•Which eukaryotes have cell walls?
•What is the major structural components for
each?
Bacteria
•Peptidoglycan
•Classification
– gram-positive and gram-negative
Archaea
•Lack peptidoglycan
•Contain other polysaccharides & proteins
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Structure: Bacterial Cell Walls
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Lipopolysaccharides
.
See Fig. 27.3
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Gram-positive & Gram-negative
Why does this classification matter?
• Within group of pathogenic (disease-causing)
bacteria, gram-negative more threatening than
gram-positive.
Gram-positive & Gram-negative
Gram-negative
• Toxic lipopolysaccarides
• Outer membrane defends bacteria against
a body’s defense system
• Antibiotic resistance
– reduces/prevents drug entry
– targeted to peptidoglycan layer
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Structures for Attachment
• Capsules
– Slime layer
• Fimbriae
• Pili
Fig. 27.4
Fimbriae
Fig. 27.12
Fig. 27.5
Structures for Movement
• Taxis
Fig. 27.6
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Structure: Internal Organization
Fig. 27.7
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Structure: Internal Organization
Plasmids
• a small ring of DNA
carrying accessory gene
Prokaryotic chromosome
• Ring - few proteins
Fig. 27.8.
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Metabolic Diversity
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Metabolic Diversity: Oxygen
• Obligate aerobes
• Obligate anaerobes
– Fermentation or
– Anaerobic respiration
Facultative anaerobes
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• How can the metabolic capabilities of
bacteria help us solve environmental
problems?
• Show movie
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Toxins in the
environment
• Bioaccummulation
• Biomagnification
Bioremediation
• use of biological processes to degrade,
transform, and/or remove contaminants
from soil and water
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Phytoremediation
• Use of plants for on-site treatment of
contaminated soils, sediments, and water
– Hyperaccumulators
• E.g., cadmium, lead, arsenic, zinc
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Phytoremediation
– Phytoremediaton & genetic engineering
• Bacteria gene to transform methylmercury
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Metabolic Diversity: Unique Capabilities
Nitrogen fixation &
Denitrification
Fig. 54.17
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Ecological Roles of Prokaryotes
Critical for the survival of life on
earth
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•
•
•
Carbon cycle
Oxygen
Nitrogen cycle
Decomposers
Fig. 54,17
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Ecological Roles: Symbiotic Relationships
between prokaryotes & eukaryotes
• Mutualism
Host = fish
Symbiont = bacteria inside fish
Fig. 27.15
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Ecological Roles: Mutualism
• Humans & Bacteroides thetaiotamicron
• Nitrogen fixing in plants
– Rhizobium spp. and plants from Legume family
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