= appearance of wings.
Once it appears it stays
A
C
1
B
A
C
2
B A
C
3
On which tree are wings an apomorphy?
On which tree are wings a synapomorphy uniting
taxa A and C?
B
Bacteria & Archae
Bacteria & Archae
• Wildly diverse
– ~ 500 species in your mouth alone
• Abundant (numerous)
– 1012 on your skin; 1014 in G. I. tract; 1 teaspoon
of soil contains billions
• Ubiquitous
– O2 free mud; salt flats; boiling hot springs;
bedrock 1500 m deep; 10 km beneath ocean’s
surface; 0° - 121° C
2/3 major evolutionary lineages
Unifying features
• Bacteria & Archae
– Unicellular
– lack a membrane-bound nucleus
• Bacteria
– Cell walls of peptidoglycan (forms tough,
rigid sheets); distinct protein-making
machinery
• Archaea
– Cell walls of polysaccharides (starches);
protein-making machinery like Eukarya
Average Prokaryotic (Bacteria
or Archaea) Cell
Some cause disease = pathogenic
•
Robert Koch (late 1800’s): “bacteria are
responsible for infectious disease”
–
–
•
Developed 4 postulates to develop causative
link between bacteria & disease
Germ theory of disease
Others are major sources of
antibacterial (antibiotic) compounds
–
Cubist pharmaceuticals
Themes in diversification
• Morphological diversity
• Metabolic diversity
Morphological Diversity
• Size
• Shape
• mobility
Morphological
• Cell wall components
are different
– Lots of peptidoglycan;
no outer membrane
– Little peptidoglycan;
outer membrane
present
• Species with outer
membrane tend to be
pathogenic
– Confers increased
resistance to
desiccation & removal
Morphological
• Common to ALL:
– Haploid (all mutations are “visible to
selection”)
– Reproduce by fission (1 -> 2 daughter cells;
vertical gene transfer)
• Like mitosis: daughter cell is an exact copy of
parent cell
– Capable of conjugation (horizontal/lateral
gene transfer)
• Transfer plasmids (parasitic genomes) &
sometimes their own genes via conjugation tubes
– Wildly promiscuous
Incredible Metabolic diversity
• Harnessing ATP (energy):
– Phototrophs use light energy
– Organotrophs use organic molecules (with
high PE) with or without O2
– Lithotrophs use inorganic molecules (with high
PE)
• Building complex Carbon molecules:
– Heterotrophs acquire from other organisms
– Autotrophs make their own (using CO2, CH4)
Metabolic diversity
Potential bioremediators
•
Aside: Virtually ALL living things rely on O2
(aerobic) for harnessing energy (ATP)
–
•
However, many bacteria are anaerobic
At polluted sites, decomposition is slow
because:
–
–
usually low in O2 (anoxic)
Pollutants are rarely good food sources
1. Fertilize site to speed bacterial growth
2. “Seed” site with additional bacteria who thrive
in low O2 (anaerobes) or can eat/use pollutants
Extremophiles are useful
• As teachers:
– Some live @ 0° C, some @ 121° C, 10 km
deep
– How do they withstand pressure and heat (we
would implode)?
– What enzymes do they have that can function
at such temps (most disintegrate)?
• As research assistants:
– Our commercial DNA polymerase comes from
a bacteria living in Yellowstone hot springs
Responsible for global changes
• 4.5 --> 2.2 Bya: no free 02
• 2.7 Bya: Photosynthetic Cyanobacteria appear
– Begin producing 02 as byproduct!
• 2.4 - 2.2 Bya: Fossil and geological record
indicate rise in oceanic O2
• 2.1 Bya: Organisms begin using O2 to make
energy; Multicellularity evolves
– O2 is a super-efficient energy producer
– Organismal metabolism can be higher, growth can
occur faster
Participants in Nitrogen cycle
• Aside: Nitrogen (N) is necessary for anything
with DNA and proteins = ALL save viruses
• Most organisms cannot use N2 (us, green plants,
fungi)
• Some bacteria can trap N2; they make it
available to the rest of us (nitrogen fixation)
– Produce Ammonia (NH3) or nitrate (NO3-)
– Live in close association with plants. Trade Nitrogen
for food
Involved in Nitrate pollution
• 2 population explosions
• Fertilize crops
• NH3 fert. Is used by
bacteria in groundwater &
soil
• They release NO3- & NO2as waste products
– Contaminate drinking water
• Cyanobacteria & algae use
NO3- as food (PE)
• Die, sink, & aerobic
decomposers eat them (PE)
• O2 depletion
Bacterial lineages
Many are commensal or
mutualistic
• Vitamin K
– E. coli make the
stuff & use it in
their metabolism
– We use it to
construct blood
clotting proteins
Many are
pathogenic
* Some are only
pathogenic when they
escape from their
normal environment
Bacterial lineages
•Chloroplasts
•Mitochondria
How did Endomembrane system
develop from prokaryotes?
• Invagination of plasma
membrane
–
–
–
–
Nuclear envelope
ER
Golgi
Transport vessicles
How did other organelles
develop?
• Cooperating prokaryotes
• Endosymbionts
– Mitochondria
– Chloroplasts
• Only organelles with:
– Separate genome
– replication & transcription
machinery
– Reproduction via fission,
independent of cell cycle
– Double membrane
Heterotrophic eukaryote engulfs cyanobacteria
Bacteria evolves into chloroplast
Land Plants
Chloroplasts evolve different pigments
Eukaryote gives up ingestion; uses chloroplasts to
produce food = autotrophic eukaryotes. Descendents
evolve into land plants
Another heterotrophic eukaryote ingests
an autotrophic eukaryote (Green algae)
Tremendous diversity in small, often
single-celled Protists
Can we map some unifying
traits?