Plasmids are usually transmitted from donor to recipient through a sex pilus. Prokaryotic metabolism can vary with respect to oxygen availability. Anaerobic respiration:substances other than 02 act as electron acceptors (e. g. no3 -, so4 2-) nitrogen metabolism. In nitrogen fixation, bacteria can convert n2 (nitrogen gas) to nh3 (ammonia) Cooperation between prokaryotes allows them to use resources they could not use individually. Concept 27. 4 : molecular systematics is illuminating prokaryotic phylogeny. Chemoautotrophs use ____ as an energy source and ____ as a carbon source: light; co2, light; organic compounds, inorganic compounds ; co2***, organic compounds; organic compounds --> chemo heterotrophs. Which type of gene transfer involves a pilus that makes direct contact between two cells: conjugation***, transduction, transformation, all of the above. Plasmid dna is what gets transferred from one dna to another in conjugation. A tentative phylogeny of some of the major taxa of prokaryotes based on molecular systematics. Comparison of traits found in the domains bacteria and archaea.