Diversity of Life

Kingdom

Diversity of Life using ribosomal RNA sequence Carl Woese

Viruses Not a living organism Parasite uses other organisms to replicate Infect all organisms, particularly bacteria 10 million/ml in ocean

 Domain Archaea  Domain Bacteria  Structurally simple, lack most organelles  Mostly microscopic  Circular DNA Prokaryotes

Eukaryotes  1 Domain: Eukarya  4 Kingdoms: Protista, Plantae, Fungi, and Animalia  Structurally complex  Have membrane-bound organelles with specialized jobs  Mitochondria and chloroplasts – organelles that were once symbiotic bacteria

Diversity of Life - Archaea Simple, primitive Old (3.8 billion years) Recently discovered (1970s) Look like bacteria, but chemically different

Diversity of Life - Archaea Have reputation as “extremophiles” Found almost everywhere Very common in oceans

Diversity of Life - Archaea Extreme high and low temperatures areas (thermophiles) Volcanic hot springs, hydrothermal vents Archaea “Strain 121” – survives up to 121°C, reduces iron into byproduct magnetite

Diversity of Life - Archaea Extreme salty regions (halophiles) Hypersaline lakes Salinity 300‰ or more Haloquadratum walsbyi

Diversity of Life - Archaea Extreme alkaline and acidic areas Extreme pressure - deep trenches Anoxic muds Archaea in acid mine drainage Picrophilus torridus – lives at 60°C and pH=0 NASA

Diversity of Life - Archaea Symbiotic associations with other organisms: Methanogens – live in digestive guts of plankton, sea cucumbers Others still being discovered green – archaeum (Cenarchaeum symbiosium) red – red sponge (Axinella mexicana) cell nuclei

Diversity of Life - Bacteria Simple, old Variety of shapes and sizes

Diversity of Life - Bacteria Found almost everywhere (including extreme environments) Found in huge quantities in the ocean

Diversity of Life - Bacteria Important part of nutrient recycling Decomposition of organic matter (dead, wastes) Food for other organisms

Diversity of Life - Bacteria Cyanobacteria (“blue-green algae”) Green, blue, and red photosynthetic pigments First photosynthetic organisms on earth Stromatolites (3 bya and today) – calcareous (CaCO 3 )

Diversity of Life - Bacteria Symbiotic associations with other organisms: Chemosynthesis in tube worms, mussels, clams at hydrothermal vents and cold seeps

Diversity of Life - Bacteria Symbiotic associations with other organisms: Digestive gut bacteria (shipworms, bone worms)

Diversity of Life - Bacteria Symbiotic associations with other organisms: Bioluminescence in squid, fish Vibrio, Photobacterium

Diversity of Life – Metabolism  Organisms that can make own food = autotrophs (“self feeders”)  Organisms that must eat other organisms or organic matter for food = heterotrophs

7 different types of pathways possible 4 heterotrophic:  Aerobic respiration  Anaerobic respiration  Nitrogen fixation  Anaerobic ammonium oxidation  3 autotrophic:  Light-mediated ATP synthesis  Photosynthesis  Chemosynthesis Diversity of Life – Metabolism

 Aerobic respiration, uses oxygen (O 2 ), “burns” organic matter to get energy: Prokaryotes and eukaryotes Decomposition of organic matter C 6 H 12 O 6 + O 2 → CO 2 + H 2 O + energy (sugar) (ATP) Diversity of Life – Metabolism

Anaerobic respiration, uses NO 3 -, SO 4 -2, or CO 2 instead of O 2 Nitrogen fixation Makes nitrogen gas (N 2 ) usable to organisms as ammonia Anaerobic ammonium oxidation All of these 3 require anoxic conditions All of these 3 are in prokaryotes only

Diversity of Life – Metabolism  Light-mediated ATP synthesis - prokaryotes only  Photosynthesis  Prokaryotes and eukaryotes (only algae and plants)  Need chlorophyll and other pigments  Converts inorganic carbon to organic  Photoautotrophs

CO 2 + H 2 O + light → C 6 H 12 O 6 + O 2 energy (sugar) Diversity of Life – Metabolism Photosynthesis

Diversity of Life – Metabolism Chemosynthesis: Energy from chemicals (H 2 S), not light Critical for life at hot and cold seeps Prokaryotes only Chemoautotrophs

Diversity of Life – Metabolism  Autotrophs must also use respiration to get ATP energy

Diversity of Life – Metabolism 7 classes of metabolic reactions possible in prokaryotes Only 2 in eukaryotes (photosynthesis, aerobic respiration)

Prokaryotes vs. Eukaryotes ProkaryotesEukaryotes Domains/ Kingdoms Bacteria, ArchaeaAnimalia, Plantae, Fungi, Protista Cellular ComplexitySimpleComplex, organelles DNA structureSimple, circularChromosomes in a nucleus Cellular Organization All unicellularSome unicellular, many multicellular Metabolic pathwaysVariety, 7 possibleOnly 2 – aerobic respiration & photosynthesis Feeding strategyAuto & heterotrophy