Question

list all types of energy metabolism for prokaryotes and the possible electron donors and acceptors for each. which of these forms of energy metabolism can be used by multicellular eukaryotes? how does this difference in the metabolic diversity affect the range of habitats that prokaryotes can inhibit compared with eukaryotes

Answer 1

Prokaryotes are those organism which do not have a true nucleus and membrane bound cell organelles. e.g Monerans (bacteria, archae, etc). The different types of energy metabolism for prokaryotes are as follows.

Nutritional modes

Nutritional mode	Energy source	Carbon source	Elaectron donor & acceptor
Photoautotroph	Light	CO2	Inorganic sulphur compounds like H2S
Photoheterotroph	Light	organic compounds	Nonsulphur aliphatic compounds
Chemoautotroph	Chemical compounds	CO2	Molecular H2,ammonium, nitrate, sulphide,etc
Chemoheterotroph	Chemical compounds	organic compounds	H2S,etc.

Areobic and anaerobic respiration

Types of bacteria	Energy source
Obligate aerobes	O2
Facultative anaerobes	both in presence & absence of O2
Obligate anaerobes	absence of O2
Facultative aerobes	both in presence & absence of O2

Nitrogen metabolism

Some prokaryotes like Cyanobacteria can able to fix atmospheric N2 to NH3 rich compounds. There are some nitrifying bacteria that convert ammonia into nitrite and nitrate. Then the denitrifying bacteria changes nitrates into N2 gas.

Sulphur metabolism

Some prokaryotes live in hostile environment like hot springs and high acidity area. They oxidise sulphur to sulphuric acid under aerobic condition and the energy derived from this is utilized in food synthesis. Under anaerobic conditions sulphur is reduce dto H2S.

Nitrogen and carbon cycle

Some nitrifying bacteria fix atmospheric nitrogen into ammonia and this is used by the plants to build amino acids, peptides, etc. The cyanobacteria is capable to fix atmospheric CO2 for synthesis of organic food during photosynthesis.