Answer:
The correct answer is "begin to cross the membrane while still being synthesized".
Explanation:
The missing answers for this question are:
A) are transported across the membrane after their synthesis is complete.
B) are synthesized on free ribosomes in the cytosol.
C) begin to cross the membrane while still being synthesized.
D) remain within the endoplasmic reticulum.
The correct answer is option C) "begin to cross the membrane while still being synthesized".
Most proteins that are destined to enter the endoplasmic reticulum to fold and suffer its post-translational modifications, begin to cross the membrane while still being synthesized. Furthermore, the subunit proteins that have a quaternary structure cross the membrane in an unfolded state and its proper folding is mediated while the multi-subunit polypeptides start to be bounded together.
