A BC A BC A BC

1 2 3

= appearance of wings.Once it appears it stays

On which tree are wings an apomorphy?On which tree are wings a synapomorphy uniting taxa A and C?

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 growth2. “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

- & NO2- as

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

Chloroplasts evolve different pigmentsEukaryote gives up ingestion; uses chloroplasts to produce food = autotrophic eukaryotes. Descendents evolve into land plants

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?