Question

Which of the following is NOT true of the endoplasmic reticulum? 

 This is the organelle that modifies proteins before secretion (such as glycosylation)

 The rough ER is involved in the translation of proteins bound for the membrane or secretion the smooth ER can synthesize membrane components

 The ER is proximal (close) to the nucleus

 The rough ER gets its name from the ribosomes studding it's surface

Answer 1

The rough ER is involved in the translation of proteins bound for the membrane or secretion.

This statement is not true of the endoplasmic reticulum. Rough ER is responsible for protein folding, packaging and processing including assembly of multisubunit proteins, glycosylation, disulfide bond formation etc. Translation is completed by ribosomes. The translated polypeptide then enters the ER for further processing. Smooth ER is responsible for lipid synthesis which is the main membrane component. ER is a part of endomembrane system and is often continuous with the nuclear membrane in the cell. Rough ER has ribosomes attached on it's surface which give the ER a rough, studded appearance, hence the name Rough ER.