This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Translation, Subject name: Biochemistry
Membrane proteins are synthesized in - 
Select and explain. 
A. Free ribosome, B. Bound ribosome, C. Nucleolus, D. Mitochondria
B: Bound ribosome
Answer: B: Bound ribosome 
Explanation: Ans. is 'b' i.e.. Bound ribosomeRibosomeso Ribosomes are the actual sites of protein synthesis^. The ribosomes are small granules of RNAs. Ribosomes are usually occur in clusters called polyribosomes attached to one mRNA molecule, an arrangement that increases the rate of polypeptide synthesis. There are two types of polyribosomes : -Free (cytosolic) : - Present free in cytosol.Bound polyribosome: - Present on rough ER.o Both types can synthesize protein : -Proteins synthesized by polyribosomesCytosolic (free) PolyribosomesBound (rough ER) Polyribosomeso Cytosolic proteins, e.g., Hemoglobino Cytoskeletal proteinso Mitochondrial proteinso Nuclear proteinso Peroxisomal proteinso Synthesize all membrane proteinsMitochondrial membraneER membraneGolgi apparatus membranePlasma membraneo Secretory proteinso Lysosomal enzymes