Domains Bacteria & Archaea

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Ceno- Meso- zoic Prokaryotes zoic ANTIQUITY Humans (Domains Bacteria & Archaea) Paleozoic Colonization KEY POINTS of land Animals Origin of solar system and 1. Decomposers: recycle organic and Earth inorganic molecules in environment; makes • >3.5 BILLION them available to other organisms. years old. 2. Essential components of symbioses. • Alone for 2 1 4

billion years Proterozoic Archaean 3. Encompasses the origins of metabolism and Prokaryotes metabolic diversity. Billions of 2 years ago3 4. Origin of photosynthesis and formation of Multicellular eukaryotes atmospheric Oxygen Single-celled eukaryotes Atmospheric oxygen

General characteristics General characteristics

1. Small: compare to 10-100µm for 0.5-5µm 4. Occur everywhere, eukaryotic cell; most numerous organisms. single-celled; may – More individuals in a form colonies. handful of soil then there are people that 2. Lack membrane- have ever lived. enclosed organelles. – By far more individuals 3. Cell wall present, but in our gut than eukaryotic cells that are different from plant actually us. cell wall.

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General characteristics General characteristics

6. Important decomposers and recyclers

5. Metabolic diversity established nutritional modes of eukaryotes.

General characteristics General characteristics

6. Important 7. Symbionts!!!!!!! decomposers and • Parasites recyclers • Pathogenic • Form the basis of organisms. global nutrient • About 1/2 of all cycles. human diseases are caused by Bacteria

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General characteristics General characteristics

7. Symbionts!!!!!!! 7. Symbionts!!!!!!! • Parasites • Commensalists • Pathogenic • They are organisms. everywhere (really). • Extremely important • There can be 10 in agriculture as million cells per well. square centimeter Pierce’s disease is caused by Xylella of skin. fastidiosa, a Gamma Proteobacteria. It causes over $56 million in damage annually in California. That’s with $34 million spent to control it! = $90 million in California alone.

General characteristics

General characteristics 7. Symbionts!!!!!!! • Mutualists 7. Symbionts!!!!!!! • Allows herbivorous • Mutualists (plant-feeding) animals to • Eukaryotic life digest cellulose and other would be low-quality plant tissues. impossible without • Termites this. • Ungulates “chewing the cud” • Lagomorph coprophagy

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General characteristics General characteristics 7. Symbionts!!!!!!! 7. Symbionts!!!!!!! • Mutualists • Mutualists • Komodo dragons and their • Mealybug endosymbionts “toxins”. with endosymbionts. • Hunt large prey and can inflict fairly minor wound. • Prey die fairly quickly from wound. • Infection by highly pathogenic Pasteurella multocida (Gamma Proteobacteria). • Prominent in saliva of dragons, but dragons have an anti- Pasteurella antibody.

Current taxonomy is TAXONOMY is problematic stabilizing • Relationships obscured by billions of • Note that “Prokaryote” years of evolution is paraphyletic. Why? • Two Domains: • Also obscured by unique bacterial • Archaea: extremophiles means of recombination (more later). (mostly), ancient, probable progenitors of • Grouped primarily by DNA sequence eukaryotes. data. • Bacteria: most • Immense genetic/genomic diversity. commonly-encountered prokaryotes.

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Characteristics Cell Surface

• Cell Surface • Archaea: plasma membrane of • Motility ether-lipids • Genome (unique in life). • Reproduction & Growth • Bacteria: a sugar • Metabolic Diversity polymer - peptidoglycan • Nitrogen Metabolism • Oxygen Relationships

Motility Cell Surface • ~half the species can move. • Cell wall is often 1. Flagella most common modified with structures (different structure from to adhere to substrate. eukaryote) • Many secrete a sticky 2. Spiral filaments: spirochetes capsule or adhere by corkscrew fimbriae (ocasionally 3. Gliding over slimy secretions called pili). (via flagellar motors without filament) • Capable of taxis (photo, chemo, geo, etc.)

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Genome Genome

• One major chromosome, • Small genomes: double stranded DNA ~1/1000th DNA molecule in ring. content of • Sometimes several small DNA rings of few genes: eukaryotes. plasmids. – Replicate independently of • No membrane main chromosome. enclosed nucleus. – Permit recombination via conjugation (later). • DNA concentrated in – Involved in resistance to ‘nucleoid’ region. antibodies/antibiotics.

Genome: Recombination via Genome transformation • Broadly, replication & translation of genetic • DNA taken up from info like that of eukaryotes; differ in details the environment and simplicity. • Used in first DNA recombinant research. • Genetic recombination: Not like eukaryotes (e.g. chiasma & crossing over)!! – Transformation – Conjugation – Transduction

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Genome: Recombination via Genome: Recombination via conjugation transduction • Direct transfer of • Transfer of DNA via DNA between cells. phage viruses. • Both plasmids and portions of bacterial chromosome.

Metabolism Reproduction & Growth Metabolic Diversity

• Meiosis & Mitosis NOT • Nutrition: PRESENT. • Asexual binary • Requires a source of carbon for fission. synthesizing organic compounds: either • DNA replication can be nearly continuous in carbon dioxide or living matter. ideal conditions (depends on pH, • Requires a source of energy to drive salinity, temperature, reactions: either light or chemical. etc.) • Generation times as fast as 20 minutes

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Metabolic Diversity: Metabolism Metabolic Diversity: Metabolism Source of Carbon Source of Energy

• AUTOTROPHS: Need only carbon • PHOTOTROPHS: Need only sunlight as

dioxide (CO2) as carbon source energy source • HETEROTROPHS: Need at least one • CHEMOTROPHS: Derive energy from organic nutrient as carbon source (e.g. oxidation of organic molecules. glucose; petroleum) • Both of these present in domain • Both of these present in domain Eucarya as well. Eucarya as well.

Metabolism Metabolism Metabolic Diversity: Combined Photoautotrophs

• Use sun for energy, Energy Source: CO2 for carbon. • Photosynthetic Sun Environment bacteria (e.g. cyanobacteria). Photoautotroph Chemoautotroph • Present in many CO2 plants and single- Source: Source: Carbon Organic celled Eucarya Photoheterotroph Chemoheterotroph molecules Which of these are present in multicellular Eucarya?

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Metabolism Metabolism Chemoautotrophs Photoheterotrophs • Oxidize inorganics (H2S, NH3) for energy. • Get enery from light

• Need only CO2 as but must obtain carbon source. carbon in organic • Unique to Bacteria and form (NOT CO2). Archaea. • Unique to Bacteria • E.g. Methanococcus jannaschii lives on and Archaea. hydrothermal vents at • E.g. Halobacterium 2600m below sea level. salinarium.

• Reduces H2 + CO2 to CH4 + 2H2O.

Metabolism Metabolism Chemoheterotrophs Nitrogen metabolism • Consume organic molecules for both energy and carbon. • Nitrogen fixation: • Common among • The only* mechanism that prokaryotes: makes atmospheric Nitrogen available to other – saprobes (decomposers) organisms. – parasites (rely on • Convert N2 into ammonia living hosts) (NH3) which is quickly • Also widespread in protonated into ammonium (NH +). Protista, Animalia, 4 Plantae. • Essential for multicellular life!

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Oxygen Relationships Oxygen Relationships

• Aerobic vs. Anaerobic • Cellular respiration: • Early life (during the • Obligate aerobes: use O2 for – Carbohydrates + O2 →CO2 cellular respiration. + H2O + energy Archaean) was • Facultative anaerobes: use • Fermentation: primarily anaerobic. O2 if it is present by carry out – Carbohydrates →CO2 + anaerobic respiration or ethanol + energy • Evolution of fermentation in anaerobic • Anaerobic respiration: photosynthesis in environment. – Carbohydrates + [X] → • Obligate anaerobes: bicarbonate + [X-] + energy Cyanobacteria poisoned by O ; use – Where [X] is a substance 2 changed all this. anaerobic respiration or other than O2 that accepts fermentation. electrons such as nitrates or sulfates

Taxonomy of Prokaryotes Archaea or Archaebacteria

• Archaea or Archaebacteria • Live in extreme – Methanogens environments – Halophiles (extremophiles): sulfur – Thermophiles hot springs, deep sea • Bacteria or Eubacteria vents, high salt – Protobacteria environments. – Chlamyidias • Lack peptidoglycan, – Spirochetes unique plasma – Cyanobacteria membrane of liquids – Gram-positive bacteria • Likely sister group of Eukaryotes

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Archaea or Archaebacteria Archaea or Archaebacteria

• Methanogens • Halophiles

– Use H2 to reduce – Saline environments. CO2 to methane – Salinity several times (CH4). higher than sea – Chemoautotrophs water. – Anaerobic – Photoheterotrophs – In swamps, marshes, deep sea vents, important decomposers.

Archaea or Archaebacteria Bacteria or Eubacteria

• Thermophiles • Grouped by – 60º-80ºCpH 2-4 molecular optimal systematics. – Chemoautotrophs – Oxidize HS

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Bacteria or Eubacteria Bacteria or Eubacteria Proteobacteria Gram positive Bacteria: • VERY diverse, grouped • Simple peptidoglycan cell wall. into five taxa based on • Rival Proteobacteria in DNA sequence data. diversity. • Most are free-living • Includes most types of decomposers. metabolism that we’ve • Some pathogenic (e.g. strains discussed. of Staphylococcus, • Includes most of the types Streptococcus, Bacillus anthracis, Clostridium of symbioses we’ve botulinum). discussed • Include the mycoplasms--the • Review the summary in only bacteria that lack cell walls Figure 27.16.

Bacteria or Eubacteria Bacteria or Eubacteria Cyanobacteria: Spirochetes: • Photoautotrophs • Helical • Only prokaryotes with • Recall motility: move by plant-like, O2-generating photosynthesis. means of rotating, internal, flagellum-like • Present in freshwater filaments. and marine environments. • Free-living and parasitic. • Often colonial--first steps toward • Chemoheterotrophs multicellularity? (like us).

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Bacteria or Eubacteria Prokaryotes: Summary

Chlamydias: • You should now have a good sense of • ALL are parasites of prokaryote biology and diversity. animals. • Including roles in metabolism, • Intercellular. symbioses, global energy cycles. • Lack peptidoglycan in the cell wall (are they • Important distinguishing characteristics gram-positive or of cell wall, motility, genome, replication. gram-negative?). • General aspects of their systematics. • Most common form of STD in USA (urethritis).