A low level of carbon dioxide labeled with 14C is accidentally released into the atmosphere surrounding industrial workers as they resume work following the lunch hour. Unknowingly, they breathe the contaminated air for one hour. Which of the following compounds will be radioactively labeled?
|A||All of the carbon atoms of newly synthesized fatty acid.|
|B||About one half of the carbon atoms of newly synthesized fatty acids.|
|C||The carboxyl atom of newly synthesized fatty acids.|
|D||About one third of the carbons of newly synthesized malonyl CoA.|
Malonyl CoA three carbons is synthesized from acetyl CoA two carbons by the addition of CO2, using the enzyme acetyl CoA carboxylase. Because CO2 is subsequently removed during fatty acid synthesis, the radioactive label will not appear at any position in newly synthesized fatty acids.