Question

A glucose molecule has carbon 14 in the first and fifth positions of the molecule. Two organisms are allowed to catabolize this molecule. One organism has Embden-Meyerof enzymes and the other has Entner-Doudoroff enzymes. What molecules of these pathways combined with the Krebs Cycle will carry a carbon 14 after one turn of the Krebs Cycle?

This question is worth 20 points, so please give me a thorough explanation. Thank You.

Answer 1

Explanation:

In this question as the first and fifth carbons of glucose are radiolabelled with carbon 14. Therefore, after the successful catabolism of glucose through enzymes of both Embden-Meyerof pathway and the Entner-Doudoroff pathway glucose is finally converted into pyruvate (a 3 carbon compund) carrying Carbon 1 which is radio-labelled. Pyruvate then enter into krebs cycle carrying C14 after one turn of the Krebs Cycle.

For more detail follow the below given figure where EMP, often simply referred to as glycolysis, is shown in red with key enzyme PFK; and the ED pathway is shown in green with key enzyme KDPG aldolase (Eda). Reactions that are shared by all pathways are shown in black. The EMP and EDD pathways are known to operate in cyanobacteria and plants. Eda, KDPG aldolase; Edd, phosphogluconate dehydratase; Eno, enolase; Fba, fructose bisphosphate aldolase; Gdh, glucose dehydrogenase; Gk, gluconate kinase; Gnd, 6-phosphogluconate dehydrogenase; Pfk, 6-phosphofructokinase; Pgi, phosphoglucose isomerase; Pgk, phosphoglycerate kinase; Tim, triosephosphate isomerase; Zwf, glucose-6-phosphate dehydrogenase.