Final answer:
Cytosolic polypeptides are transported to a target organelle through post-translational import. This involves the recognition of targeting signals on the polypeptide chains and the use of specific translocator complexes to facilitate the import into the organelle.
Step-by-step explanation:
Cytosolic polypeptides are transported to a target organelle through post-translational import, which is the correct answer option B. Post-translational import refers to the process of transporting polypeptide chains to their final destinations after they have been synthesized in the cytosol. For some organelles, such as mitochondria, the transport is mediated by protein translocators that recognize specific targeting signals on the polypeptide chains.
For example, mitochondrial targeting signals are usually located at the N-terminus of the polypeptide and are recognized by translocase of the outer mitochondrial membrane (TOM) and translocase of the inner mitochondrial membrane (TIM) complexes. These complexes facilitate the import of polypeptides into mitochondria where they undergo further processing and folding to become functional proteins.