The video tutorial explains anaplerotic reactions in the TCA cycle, highlighting how substrates can be siphoned off for biosynthesis or replenished. It details the production of oxaloacetate from asparagine and its role in the TCA cycle. The tutorial also covers the synthesis of glutamate and glutamine from TCA intermediates, emphasizing the role of enzymes like transaminase and glutamate dehydrogenase. The video concludes with additional examples of anaplerotic reactions, such as the conversion of succinyl CoA to heme and fumarate's role in the urea cycle.

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