Question

All proteins are synthesized by ribosomes in the cell. Some ribosomes float freely in the cytosol, while others are bound to the surface of the endoplasmic reticulum. Most proteins made by free ribosomes function in the cytosol. Proteins made by bound ribosomes either function within the endomembrane system or pass through it and are secreted from the cell. Which of the following proteins are synthesized by bound ribosomes 1) Actin 2) DNA polymerase 3) Lysosomal enzyme 4) Ribosomal Protein 5) Insulin 6) ER transmembrane protein

Answer 1

Answer:  3) Lysosomal enzyme, 5) Insulin and 6) ER transmembrane protein are all synthesized by bound ribosomes.

Explanation:

Proteins may be synthesized in the cytosol by free and unbound ribosomes for work in the nucleus like DNA polymerase; or to function in the cell's cytosol, like actin.

However, bound ribosomes synthesize proteins for the Endoplasmic Reticulum (ER). They contain a small initial signaling sequence, which facilitates the attachment of these proteins to the membrane of the ER and their passage into the ER lumen.

Additionally, they carry out the synthesis of Endomembrane system-bound lysosomal enzymes, responsible for packaging and exporting compounds, along with, the protein chain hormone insulin, which is destined to leave  the cell.