Cellular Respiration

AP Biology· difficulty 4/5

Researchers feed cells 14C-labeled acetyl-CoA (carbons marked).

Acetyl-CoA 2C* Citrate (6C) CO2 (5C) CO2 (4C)

On the FIRST turn of the cycle, where is the labeled carbon initially detected?

  • A

    Released immediately as CO2

  • B

    Released as O2 from oxaloacetate

  • C

    Stored permanently in NADH

  • D

    In the citrate carbons; the labeled carbons are not released as CO2 in the first turn

    check_circle

Explanation

The CO2 lost during the first turn of the cycle comes from oxaloacetate carbons, not the newly added acetyl-CoA carbons. Labeled carbons are detected as CO2 only on later turns.

Want 10 more like this — adaptive to your weak spots?

Related questions