Biological Nitrogen Fixation and Sulfur Assimilation

These flashcards cover key terms related to sulfur assimilation, nitrogen fixation, and associated biological processes.

Sulfur assimilation

The process by which plants incorporate sulfur into organic compounds.

Rhizobium

A genus of bacteria that fix nitrogen in symbiosis with legumes.

Nod factors

Chemical signals produced by rhizobia that induce root hair curling and formation of nodules.

Nitrogenase

An enzyme complex responsible for the conversion of atmospheric nitrogen (N2) into ammonia (NH3).

Leghemoglobin

A protein that binds oxygen in legumes, supplying it to bacteria in nodules while protecting nitrogenase from oxygen.

Endosymbiosis

A symbiotic relationship where one organism lives inside the cells of another, as seen in nitrogen-fixing bacteria and legume plants.

Determinate nodules

Nodules that have a specific structure and lose their apical meristem after a certain growth stage.

Indeterminate nodules

Nodules that retain a meristem and continue cell division throughout their life.

Flavonoids

Plant secondary metabolites that attract rhizobia during the nodulation process.

Symbiosome

A membrane-bound structure in plant root nodules that contains bacteria after infection.

Sulfated compounds

Organic compounds that contain sulfur and have been modified by the addition of sulfate groups.

O-acetylserine (OAS)

An intermediate compound in the biosynthesis of cysteine from sulfate.

Biological nitrogen fixation

The process by which certain organisms convert atmospheric nitrogen (N2) into ammonia (NH3), making it available for plants.

Cyanobacteria

Photosynthetic bacteria known for their nitrogen-fixing ability, often forming symbiotic relationships with ferns.

Nitrogen-fixing symbiosis

The mutualistic association between nitrogen-fixing bacteria and their plant hosts that enhances nitrogen availability.

Communication in nodulation

The signaling process involving flavonoids from plants and Nod factors from bacteria to initiate nodule formation.

Calcium oscillation

A signaling mechanism crucial for the nodulation process, influenced by Nod factor perception.

ATP

A molecule that serves as a primary energy carrier in cells, used in processes like nitrogen fixation.

Sulfate

An inorganic ion of sulfur that is vital for plant sulfur assimilation and protein synthesis.

Bacteroids

Differentiated forms of rhizobia present in plant root nodules that fix nitrogen.

Haber-Bosch process

An industrial process for synthesizing ammonia from nitrogen and hydrogen, critical for fertilizers.

Pyrophosphatase

An enzyme that catalyzes the hydrolysis of pyrophosphate to release energy.