Question

A cell biologist compared the properties of rough endoplasmic reticulum (ER) and smooth ER. She found that one type of ER is used for protein storage, and the other is used for lipid storage. What accounts for this difference? a Smooth ER creates amino acids for ribosomes to form into proteins. b Smooth ER works with the nucleus to synthesize protein. c Rough ER forms proteins and transports them to the mitochondria. d Rough ER has ribosomes on its surface.

Answer 1

The correct answer is d) Rough ER has ribosomes on its surface.

The rough endoplasmic reticulum (ER) is studded with ribosomes, which are the sites of protein synthesis. This gives it a "rough" appearance under a microscope. The presence of ribosomes enables the rough ER to synthesize proteins that are either secreted from the cell, integrated into cellular membranes, or sent to an organelle.

On the other hand, the smooth ER lacks ribosomes and is primarily involved in the synthesis of lipids, metabolism of carbohydrates, and detoxification processes. It does not have the same capability for protein synthesis as the rough ER. Thus, the identity of the ER as rough or smooth is what accounts for their different functions related to protein and lipid handling.