[Campbell Biology P.155] A newly synthesized enzyme, E, is crucial for a specific modificati... | Practice Question

A newly synthesized enzyme, E, is crucial for a specific modification that occurs only in the cis cisternae of the Golgi apparatus. If, due to a cellular malfunction, enzyme E is accidentally carried forward to a more trans region of the Golgi along with maturing cisternae, how would the cell most likely restore its proper function according to the cisternal maturation model?

  • A: Enzyme E would be degraded and new enzyme E synthesized in the cis region.
  • B: Enzyme E would be transported 'backward' to less mature Golgi cisternae via recycling vesicles.
  • C: The affected trans cisterna would revert back to a cis cisterna.
  • D: Enzyme E would remain in the trans region, and the modification would simply occur there.

Explanation

The text and Figure 6.12 specifically step 5 explicitly state that 'some vesicles recycle enzymes that had been carried forward in moving cisternae, transporting them 'backward' to a less mature region where their functions are needed.' This mechanism ensures that enzymes are returned to their proper functional location.