Question

A suspension of yeast cells is being grown under anaerobic conditions such that glucose is degraded to ethanol and carbon dioxide. To follow this process by monitoring the release of CO214, at which positions in the glucose molecule would the C14 label need to be incorporated

Answer 1

Answer:

carbons 3 and 4

Explanation:

Alcoholic fermentation is an anaerobic (non-oxygen-requiring) pathway capable of converting one mole of glucose (C6H12O6) into two moles of ethanol (C2H5OH) and two moles of carbon dioxide (CO2), producing during this process two moles of ATP. The overall chemical reaction is as follow: C6H12O6 (glucose) >> 2 C2H5OH (ethanol) + 2 CO2.  During this process (fermentation), energy is obtained from the glycolysis process by which each glucose molecule is broken down into two pyruvate molecules (2 CH3COCOO−). Pyruvic acid is an organic acid that ionizes to produce a hydrogen ion and a molecule of pyruvate. Subsequently, this pyruvate is then converted into ethanol and CO2, generating NAD+, i.e., the oxidized form of nicotinamide adenine dinucleotide or NAD, which is required for glycolysis (and therefore to produce ATP). Moreover, dismutation refers to the redox reaction by which one compound with an intermediate oxidation state converts into two compounds. In consequence, the CO2 generated during fermentation arises from the dismutation of pyruvic acid. During this process, the major source of CO2 is carbon 3 (C3) and carbon 4 (C4) of the glucose as a result of the dismutation of pyruvate, and thereby these positions in the glucose molecule would the C14 label need to be incorporated.