This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Metabolism of nucleic acids, Subject name: Biochemistry
[{'content': 'A protein to be secreted from the cell is most likely to have \nSelect and explain. \nA. A hydrophilic signal sequence at its carboxyl terminus, B. Mannose-6-phosphate, C. A hydrophobic signal sequence at its amino terminus, D. A binding site for the mitochondrial membrane', 'role': 'user'}, {'content': 'Answer: C \nExplanation: A protein to be secreted from the cell usually has a hydrophobic region at its amino terminus, which causes the ribosome synthesizing that protein to become bound to the endoplasmic reticulum. The protein molecule enters the endoplasmic reticulum as it is being made. The signal sequence is cleaved off by the signal peptidase and carbohydrate residues are attached inside the endoplasmic reticulum. Additional carbohydrate residues are attached as the protein moves through the Golgi apparatus on its way to the outside of the cell. Proteins that are destined for the lysosomes are marked by the addition of mannose-6-phosphate. Ref : Biochemistry by U. Satyanarayana 3rd edition Pgno : 553', 'role': 'assistant'}]