Although the TCA cycle primarily operates as a catabolic pathway, it is also employed to synthesize intermediates (e.g. the
amino acid, aspartate is produced by transamination of oxaloacetate). The oxaloacetate required could be taken out of the
cycle, although it has to be remembered that some more oxaloacetate would have to be added (generated from pyruvate) in
order to keep the cycle turning. The most important role of the TCA cycle from the synthetic viewpoint however is its place
in the conversion of lipid into carbohydrate, which occurs in germinating oil seed. Here the TCA cycle is essentially
modified by by-passing those steps in the cycle involving the loss of CO2. Two new reactions are introduced: the conversion
of isocitrate into glyoxylate and succinate and the synthesis of malate from glyoxylate and external acetyl coenzyme A.