Prokaryotic Domains:
Bacteria & Archaea
What Themes Occur in the Diversification
of Bacteria and Archaea?
- diversity appears overwhelming
- focus on 2 themes: diversification in
morphology and metabolism
Morphological Diversity
Morphological Diversity among Bacteria and
Archaea
Small
Large
Compare relative sizes
Size varies
The sizes of bacteria and archaea vary.
Mycoplasma cells (left) are about 0.5 µm in
diameter, while Thiomargarita namibiensis cells
(right) are about 150 µm in diameter.
Morphological Diversity among Bacteria and
Archaea
Shape varies
The shapes of bacteria and archaea vary
from rods such as Bacillus anthracis
(left) and spheresto filaments or spirals
such as Rhodospirillum.
In some species, such as Streptococcus
faecalis (right), cells attach to one
another and form chains.
Morphological Diversity among Bacteria and
Archaea
Mobility varies
A wide variety of bacteria and archaea use flagella
(left) to power swimming movements. These
cyanobacterial cells (right) move by gliding across
a substrate.
Gram Staining Distinguishes Two Types
of Cell Walls in Bacteria
Distinguishing Bacteria by Staining
Gram-positive cells retain Gram stain more
than Gram-negative cells do.
Gram-positive
cells
The composition of plasma membranes
Gram-negative
cells
and cell walls are particularly important
Gram Staining Distinguishes Two Types of Cell Walls in
Bacteria
Gram Staining Distinguishes Two Types of Cell Walls in
Bacteria
Gram-positive
cell wall
Gram-negative
cell wall
Polysaccharides
Cell
wall
Peptidoglycan
Polysaccharides
Cell
wall
Outer
membrane
Peptidoglycan
Protein
Plasma
membrane
Metabolic Diversity
Plasma
membrane
Protein
Metabolic Diversity
Producing ATP
•
Bacteria and Archaea can use almost anything as
food, and biochemical capabilities are astounding
• Phototrophs: use ________ energy to promote electrons to
the top of _____________________
• ATP produced by _______________
•
fundamental nutritional needs:
1.
?
• Chemoorganotrophs: oxidize _________ with high potential
energy
• ATP produced by cellular respiration using__________
2.
?
• Chemolithotrophs: oxidize ___________ with high potential
energy
• ATP produced by cellular respiration with __________
Metabolic Diversity
Metabolic Diversity
Obtaining Building Block Compounds
Summary:
• Heterotrophs …………..
• ways to produce ATP:
phototrophs
chemoorganotrophs
chemolithotrophs
• All together these are _______ general methods for obtaining
the materials needed by these living organisms
• ways to obtain carbon:
autotrophs
heterotrophs
• Autotrophs ………..
Total: ____ general methods (_____ sources of energy times____
sources of carbon) for obtaining the materials needed
Metabolic Diversity
Metabolic Diversity
Bacteria and Archaea: Importance
Chemistry for photosynthesis, cellular respiration, and fermentation ??
Producing ATP via Photosynthesis
Why are Bacterial Chlorophylls So
Diverse?
• Cyanobacteria: chlorophyll a and b
• Photosynthetic species: use light energy to raise electrons
to high-energy states
• As electrons move through the electron transport chain,
energy released is used to generate ATP
• Species that use water as a source of electrons carry out
__________ photosynthesis
• Species that use molecules other than water as the
electron donor carry out _____________ photosynthesis
• Researchers have isolated 7 additional chlorophylls in photosynthetic
bacteria
• Different groups of photosynthetic bacteria contain one or more of the
distinctive chlorophylls
Implication?
• Photosynthetic species using different chlorophylls ?
• Diversity of pigments has been an important mechanism for ?
Cellular Respiration is Based on Electron
Transport Chains
• Bacteria and archaea can exploit a wide variety of electron
donors and acceptors to accomplish cellular respiration
Cellular Respiration is Based on Electron
Transport Chains
• When electron donors other than sugars and electron acceptors
other than oxygen are used, byproducts other than _____ and
_________________ are produced
Nitrogen Atoms Cycle through Environments in Different Molecular Forms
Why is the metabolic diversity of Bacteria
and Archaea important?
- explains ______________ diversity
N2
in atmosphere
Organic compounds
with amino (–NH2)
groups
- occupy almost all habitats because they utilize a huge variety of
molecules as ______________________________
- can use organic solvents and fuels as electron donors and acceptors:
_________________________
Fixation by
bacteria and archaea
Denitrification
by bacteria
and archaea
Uptake
from soil
Decomposition
by bacteria,
archaea, fungi
Decomposition
Uptake
from soil
NO3–
(nitrate)
- play a key role in cycling of ____________________
Plants
Uptake
from soil
Nitrification
by bacteria
NO2–
(nitrite)
NH3
(ammonia)
Decomposition
Nitrification
by bacteria
Fig. 28.16
Fermentation
Obtaining Building-Block Compounds
is a strategy for making _____ without using electron
transport chains, but _____ efficient than cellular respiration
• Fixing carbon via the Calvin cycle: used by autotrophs – cyanobacteria
and plants
• Calvin cycle in fixing carbon is not always used; other pathways
include:
Bacteria, Clostridium aceticum, can ferment ethanol, acetate, fatty acids, and
glucose
other bacteria ferment lactose; products are propionic acid and carbon dioxide
1. methanotrophs: use ___________ as a C source to produce more
complex organic compounds
2. bacteria using ____________
3. bacteria using ____________
• Compared to eukaryotes, the metabolic capabilities of bacteria and
archaea are varied and complex
Key Lineages of Bacteria and Archaea
Key Lineages of Bacteria and Archaea
•
The relationships among the major lineages within Bacteria and
Archaea are still uncertain in some cases
•
•
Bacteria are a monophyletic group
Within this group there are at least 16 major lineages
- many lineages within the Domain
Bacteria
* Focus on morphological and metabolic
diversity, impact on humans, ecological
importance
Spirochetes
Firmicutes
• are Gram positives and most are rod shaped or spherical
• are important components of soil
• some species in this group cause diseases, yet we use some to
ferment milk into yogurt
Lactobacillus bulgaricus (rods)
and Streptococcus thermophilus
• spirochaeles (spirochetes) are distinguished by their corkscrew shape
and unusual flagella
• most produce ATP via fermentation
• common in aquatic habitats
• some cause diseases: syphilis and Lyme disease
Treponema pallidum
Chlaymdiales
Actinobacteria
•
•
•
•
Gram positive
shape varies from rods to filaments
many species are heterotrophs
some species live as decomposers in soil; some live in
association with plant roots and fix nitrogen
• tuberculosis and leprosy are caused by members of this group
• species from the genus Streptomyces produce over 500 distinct
antibiotics
Chlamydia trachomatis
Chlamydia
inside infected
host cell
Streptomyces griseus
Live only inside animal cells
A Streptomyces species that produces the antibiotic Streptomycin
Proteobacteria
Cyanobacteria
Stalked bacterium
Caulobacter crescentus
• contain chlorophyll
• formerly known as “blue-green algae”
• all perform oxygenic photosynthesis
Fruiting bodies
Chondromyces crocatus
Nostoc species
Stalk
• proteobacteria form five major subgroups and are very diverse in morphology
and metabolism
Archaea
•
live in virtually every habitat, including extreme environments
•
domain is composed of at least two major lineages
•
domain was discovered so recently that two additional lineages may
exist
•
are monophyletic
•
no known parasitic archaea
Crenarchaeota
Sulfolobus species
- can be shaped like filaments,
rods, discs, or spheres.
- metabolically diverse
- are the only life-forms present
in certain extreme
environments, such as highpressure, very hot, cold, or
acidic environments
live in sulfur-rich hot springs
Some Euryarchaeota Live in HighSalt Habitats
Halobacterium NRC-1
- come in many shapes
- live in every conceivable
habitat, including high-salt,
high-pH, and low-pH
environments.
- include the methanogens
(live in swamps and guts of
mammals)
Salt ponds where
seawater is
evaporating
live in high salt habitats