MICB 201 Chapter Notes - Chapter 21: Nitrogen Fixation, Photophosphorylation, Heterocyst
Document Summary
Prokaryotic organisms: fix nitrogen at room temperature and pressure (using nitrogenase) Reducing nitrogen not necessarily just change in state. Remove electrons from organic molecules and pass to nadh or nadph. Nadh carry electrons to etc which reacts with o2. Atp is used to fix nitrogen to nh4+ Glutamine is used by different parts of the plants (root and leaf tissue) Reaction is inhibited in the presence of oxygen due to enzyme damaged. As it gets depleted, equilibrium shifts by releasing o2 from leghemogloblin. Plant residues are plowed back into the field decomposed by bacteria that normally live in soil (make extracellular enzymes and use some of the amino acids in biosynthesis) and becomes fertilizer for the next rotation. Genes for psii is not expressed in the heterocyst (psi-psi cyclic photophosphorylation) N fixation doesn"t occur in vegetative cell. Heterocyst is like a glutamine factory (fixing/reducing n2 from air to ammonia)
