Archaea

Cyanobacteria

25% total C fixation annually. The electron donor is H2O. 2 main genera = Synechococcus and Prochlorococcus. Eaten as health supplements

Archaea in the Carbon cycle - Methane production Methanogens

3 pathways to produce methane. Fastiduous anaerobes - Hydrogentrophic, acetotrophic, methylotrophic. Large genomes, primitive cell differentiation. They have diverse habitats - rubbish dumps -> Human digestive tract

Nitrogen Cycle - Ammonia Oxidation

5% prokaryotic cells on land, 20% of marine system. Nitrification - NH3 --> NO3- in soil. This increases availability of N for uptake by plants: - Nitrication performed by 2 groups: Ammonia oxidisers + nitrate oxidisers - NH3 ---> NO2 done by Ammonia-oxidising bacteria + Archaea NO3- leached from soil = pollution. NO3- available for denitrification processes - generates greenhouse gas N2O. NH3--->NO2- uses enzyme - Ammonia monoxygenase

How do bacteria generate energy?

ATP is generated in 2 ways: Substrate level phosphorylation + Oxidative Phosphorylation. Electron donors - Organic = Organotrophs + Inorganic = Lithotrophs Carbon sources - Autrophy = CO2 + Heterotrophy -organic compounds

What types of metabolism are there?

Aerobic - Aerobic respiration, Oxygenic photosynthesis + Anoxygenic photosynthesis. Anaerobic - Fermentation, Anaerobic respiration + Anoxygenic photosynthesis

How are the flagella different to those of Bacteria?

Archaea flagella superficially similar bacterial flagella - non-homologous (Convergent evolution). Flagella are made by adding subunits onto the base, unlike Bacterial flagella which are thicker + hollow, flagellin subunits pass through

Methanogenesis

CO2 + 4H2---->CH4 + 2H20. The TEA is Carbon. Final step is decay of organic matter - during decay process, EAs (O2, S, NO3) decrease, H2 and CO2 increase. Organic compounds produced by fermentation also accumulate.

Summary of Archael features

Cell wall - some contain Pseudomurein. Cell membrane - ether linked lipids Ribosomal structure - shared with Bacteria + Eukarya No fatty acid synthesis tRNA sequence + metabolism

Green Sulpur bacteria

Electron donors - H2S, S or S2O3(2-). Are sphere, rod + spirals. Photolithotrophs: Use PS1 to split e- from H2, H2S or other reduced-sulfur compounds. Require extensive membrane systems full photopigments for light absorption

Purple Non-Sulphur bacteria

H is an electron donor, most species are aerobic and mixotrophic. Diverse, rods, ovoid, flagellated, ring shaped or spiral. Typical genera = Rhodospirillum, Rhodopseudomonas + Rhodobacter

Purple Sulphur Bacteria

H2S as electron, respire anaerobically. Habitat - illuminated anoxic zones of aquatic environments, some halophiles - soda lakes + salterns

Green Non-Sulphur bacteria

Known as Chloroflexi, use H2 as electron acceptors, Photoheterotrophic, moderately Thermophilic. Lack internal membranes, Chloroflexus species contain photosynthetic apparatus.

Summary of life needs + Energy Possibilities

Life needs: An energy source, Carbon source, an Electron donor + Electron acceptor - most energy is generated in the ETC Energy Possiblities:- Light energy (Photosynthesis) = PHOTOTROPHY, Chem. bond energy (respiration)= CHEMOTROPHY.

Microbial relationship with Oxygen - Aerobes and Anaerobes

Molecular oxygen harsh oxidizing agent, V. harmful if no protective mechanism. Same oxidizing ability makes it powerful EA in respiration. Aerobes: aerobic respiration as principle energy generator - O2 as TEA Anaerobes: Never developed protective mechanisms against O2 - live in free oxygen environments i.e. Animal IT +lake sed. Many phototrophs use anoxygenic photosynthesis, no O2 prod.

Archaea

More closely related to Eukarya - no group is ancestral to the others. More chemically + structurally diverse. No Peptidoglycan + it is semi rigid

4 nutritional categories

Photoautotroph - Bacteria, plants, algae - Light for energy + CO2 for C Photoheterotroph - Light for energy + organic compounds for C Chemoheterotroph - Single organic compound act as source of energy for C Chemoautotroph - oxidise inorganic chemical compound for energy + CO2 as C source Humans are Chemoheterotrophs and Plants are Photoautotrophs

Phototrophy

Pigment absorbs suns energy, electrons at a high energy level released through ETC generating energy in the form of ATP. 2 types : Anoxygenic - Bacteriochlorophyll + 1 reaction centre Oxygenic - uses Chlorophyll + 2 reaction centre

Bacterial Metabolism + Phototrophy - Metabolsim

Set of chemical reactions in living organisms that maintain life. Some bacteria use citrate as C-source, some need O2 to grow. CATALASE test: if microbe produces oxygen. OXIDASE test: changes colour to purple, shows cytochrome oxidase present

What is the composition of an Archaen cell wall + membrane?

The lipids are unique, they are: Ether linked Side chains are not FAs, they are branched Isopreses Different Chiral form of glycerol compared to Bacteria + Eukaryotes. L-glycerol + phosphate Some possess lipid monolayers. Cell walls - made up of Surface-layer proteins, form S-layer

Heliobacteria

Use PS1 type reaction centre, bacteriochlorophyll g - unique absorption spectrum. Typically use H2S as an electron donor. Photosynthesis place at cell membranes, gram -ve. Certain forms have heat resistant endospores. Anaerobic nitrogen fixers