Question

Your neighbors have been feeding the birds – a lot – and now they’ve got rats in their yard, happily feasting on the leftover birdseed. You don’t want the rats near your house, and having little regard for the life of vermin, you decide to place a little “deterrent” on your property. Nosing around in a lab, you find arsenic. OK, you are smart enough not to actually use it, but you can’t help but think about it...

If a rat ingests arsenic, the enzyme __________________________ will be inhibited, and the metabolic intermediate ___________________________ will NOT be converted to ___________________________ which is the key entry point to the energy-generating pathway known as the ___________________________. Instead, this metabolic intermediate will be shunted into the metabolic pathway known as ___________________________ which does not require the function of the inhibited enzyme. The glucose- derived end-product of this pathway is ___________________________ and the net energy yield from glucose is ___________________________ NADH and ___________________________ ATP.

Answer 1

Your neighbors have been feeding the birds – a lot – and now they’ve got rats in their yard, happily feasting on the leftover birdseed. You don’t want the rats near your house, and having little regard for the life of vermin, you decide to place a little “deterrent” on your property. Nosing around in a lab, you find arsenic. OK, you are smart enough not to actually use it, but you can’t help but think about it...

If a rat ingests arsenic, the enzyme pyruvate dehydrogenase (PDH) will be inhibited, and the metabolic intermediate pyruvate will NOT be converted to Acetyl CoA which is the key entry point to the energy-generating pathway known as the TCA or Citric Acid Cycle. Instead, this metabolic intermediate will be shunted into the metabolic pathway known as Anaerobic glycolysis which does not require the function of the inhibited enzyme. The glucose- derived end-product of this pathway is lactate and the net energy yield from glucose is  2 NADH and 2 ATP.

Additional explanation:

When the enzyme pyruvate dehydrogenase is inhibited, it cannot convert pyruvate to Acetyl CoA which in turn means that there is no Acetyl CoA to for the TCA cycle to take place. In such a situation, the most common fate of the pyruvate formed will be its conversion to lactate. The overall process of the conversion of glucose to lactate (anerobic glycolysis) produces 2 ATP and 2 NADH. The lactate formed can be converted back to glucose by the Cori Cycle.