Which one of the following statements about the endomembrane system is correct?
A) Most of the phospholipids of the endomembrane system are synthesized in the mitochondria.
B) The endoplasmic reticulum is continuous with the plasma membrane.
C) Mitochondria function in the modification and sorting of lipids and proteins.
D) Proteins that will be secreted from the cell are likely to be found in closed spaces bounded by membranes of the endomembrane system.
E) Ribosomes move lipids and proteins among the different organelles of the endomembrane system.
Answer: D) Proteins that will be secreted are always enclosed by some membrane of the endomembrane system until they are secreted.