Imagine that I start off with 10 molecules of oxaloacetate in a mitochondria. I now allow the TCA to run just enough to generate 20 molecules of CO2 (assuming that oxaloacetate is being used only for TCA in these mitochondria).

Create a question based on the data given. Then answer to your own question.

The correct option is option D which is  10 – 1 molecule of Oxaloacetate (OAA) is regenerated for every molecule of Acetyl-Coenzyme (AcCoA) used.

Explanation:

As the complete question is not given, the complete question is as below

Imagine that I start off with 10 molecules of oxaloacetate in a mitochondria. After running the TCA to generate 20 molecules of CO2, how many molecules of oxaloacetate will be left in the mitochondria (assuming oxaloacetate is being used only for TCA in these mitochondria)?

A) 30 – each molecule of CO2 generated corresponds to an increase of one OAA

B) 20 – every two molecules of CO2 generated corresponds to an increase of one OAA

C) 0 – two molecules of CO2 generated corresponds to one AcCoA used in the TCA; each AcCoA requires one molecule of OAA

D) 10 – one molecule of OAA is regenerated for every molecule of AcCoA used

Each cycle of TCA result in consumption of 1 Acetyl-Coenzyme (AcCoA) and 1 Oxaloacetate (OAA) molecule to give rise to 3 molecules of NADH and 2 molecules of CO2 per cycle. But at the end of each cycle, OAA molecule is regenerated. So the number of oxaloacetate(OAA) molecules remains unchanged.

Thus the correct option is option D which is  10 – 1 molecule of Oxaloacetate (OAA) is regenerated for every molecule of Acetyl-Coenzyme (AcCoA) used.

many other transport proteins, often called pumps, move materials against a concentration gradient. active transport drives molecules across a membrane from a region of lower concentration to a region of higher concentration. this process, shown in figure 5.1, uses transport proteins powered by chemi- cal energy.