Question

as shown in figure 9.10 in the textbook, citrate is the initial carboxylic acid in the citric acid pathway and oxaloacetate is the final carboxylic acid. to determine whether the citric acid pathway was cyclic, hans krebs treated cells with radioactive oxaloacetate. what would have been the result of krebss experiment if the pathway were linear instead of circular?
radioactive oxaloacetate + acetyl coa would produce radioactive citric acid.
radioactive oxaloacetate would produce radioactive acetyl coa.
radioactive oxaloacetate + acetyl coa would produce no radioactive citric acid cycle intermediates.
radioactive oxaloacetate + acetyl coa would produce radioactive glucose.
i dont know yet

Explanation:

If the citric acid pathway were linear, the radioactive oxaloacetate would not cycle back to combine with acetyl - CoA repeatedly. In a linear pathway, the reaction would proceed in one - direction. Oxaloacetate is the final carboxylic acid in the linear assumption. When combined with acetyl - CoA (which is not radioactive in this thought - experiment about the result if it were linear), there would be no further cycling to regenerate intermediates. So, radioactive oxaloacetate + acetyl CoA would produce no radioactive citric acid cycle intermediates as there is no recycling to incorporate the radioactivity into other cycle intermediates.

Answer:

Radioactive oxaloacetate + acetyl CoA would produce no radioactive citric acid cycle intermediates.