Lecture 7 & 8: N Fixation and Ammonia Assimilation

These flashcards cover the essential concepts related to nitrogen fixation and ammonia assimilation, including relevant enzymes, biochemical pathways, and the significance of nitrogen metabolism in living organisms.

What is nitrogen fixation?

The reduction of N2 to NH3.

What enzyme complex is required for nitrogen fixation?

Nitrogenase, which consists of a reductase and nitrogenase.

What metal cofactors are commonly found in nitrogenases?

Molybdenum or vanadium plus iron.

What is the primary source of ammonia for cells?

Ammonia (NH3) is derived primarily from atmospheric N2 gas.

What is the role of ATP in nitrogen fixation?

ATP provides the energy required to overcome the stable N-N triple bond during fixation.

How do plants and microbes obtain ammonia from nitrate?

They can reduce nitrate to ammonia using nitrate reductase and nitrite reductase.

What products are generated during nitrogen fixation?

Nitrogenases generally produce both H2 and NH3.

What is the first step in ammonia assimilation by bacteria?

Reductive amination of α-ketoglutarate to form glutamate (GLU).

What enzyme forms glutamate from α-ketoglutarate and NH3?

Glutamine synthetase.

What cofactor do transaminases have?

Pyridoxal phosphate (PLP).

What is the significance of tetrahydrofolate (THF) in metabolism?

THF transfers one-carbon units in biosynthesis.

What is the primary function of glutamate in amino acid metabolism?

Glutamate is the amino group donor for most transaminations.

What is the main type of amino acids sourced from glutamine?

Glutamine is the source of amino groups for the biosynthesis of several other compounds.

What is the role of sulfanilimide antibiotics?

They inhibit folate biosynthesis in bacteria.

How are amino acids typically synthesized in industry?

By chemical synthesis or from overproducing bacteria.

What plant protection mechanism involves glyphosate?

It inhibits aromatic amino acid biosynthesis and is used as a herbicide.

Why is the enzyme dinitrogenase reductase important?

It is part of the nitrogenase complex that facilitates nitrogen fixation.

What process does glutamate synthase catalyze?

The transfer of the amino group from glutamine and α-ketoglutarate to form two molecules of glutamate.