I think bound ribosomes are involved in making proteins that are secreted, but I
ID: 49834 • Letter: I
Question
I think bound ribosomes are involved in making proteins that are secreted, but I'm seeing people say the answer is D. Is this right and why?
Insulin is a protein secreted by the cells into our blood stream. The Islets of Langerhans cells in
pancreas contain__?
A. Mostly free ribosomes in the cytosol to produce Insulin
B. Mostly bound ribosomes to the endomembrane system and the resulting Insulin marked by signal
peptides
C. Mostly bound ribosomes to the endomembrane system and the resulting Insulin not marked by signal
peptides
D. Mostly free ribosomes in the cytosol that attach a signal peptide to Insulin after translation
Explanation / Answer
C. Mostly bound ribosomes to the endomembrane system and the resulting Insulin not marked by signal peptide.
Proteins are packaged in vesicles in the Golgi apparatus and are secreted via exocytosis, all around the cell. Cells that secrete constitutively have Golgi apparatus scattered throughout the cytoplasm. No external signals are needed to initiate this process. The Golgi apparatus is found in a supranuclear position (between the nucleus and the secretory surface). Examples of cells that use regulated pathway. , beta cells of the pancreas (secrete insulin)