Final answer:
The endoplasmic reticulum (ER) is involved in modifying proteins and synthesizing lipids. The rough endoplasmic reticulum (RER) is responsible for protein synthesis, while the smooth endoplasmic reticulum (SER) is involved in lipid synthesis, carbohydrate metabolism, and detoxification.
Step-by-step explanation:
The endoplasmic reticulum (ER) is a series of interconnected membranous tubules that collectively modify proteins and synthesize lipids. The rough endoplasmic reticulum (RER) is studded with ribosomes and is involved in protein synthesis, while the smooth endoplasmic reticulum (SER) does not have ribosomes and is involved in lipid synthesis, carbohydrate metabolism, and detoxification of toxic compounds within the cell.