Final answer:
The endoplasmic reticulum (ER) includes both rough and smooth types, with the rough endoplasmic reticulum (RER) being ribosome-studded for protein synthesis and transport, and the smooth endoplasmic reticulum (SER) being involved in lipid and hormone synthesis, carbohydrate metabolism, and detoxification.
Step-by-step explanation:
The endoplasmic reticulum (ER) is a crucial organelle in eukaryotic cells that comes in two forms: the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER). The RER is characterized by its studded appearance due to the presence of ribosomes on its surface. These ribosomes are sites of protein synthesis, where proteins are translated and inserted into the lumen of the RER, then transported within the cell in transport vesicles. Meanwhile, the SER appears smooth because it lacks ribosomes and is involved in the synthesis of lipids and steroids, metabolism of carbohydrates, regulation of calcium levels, and detoxification of toxic compounds.
Rough ER works closely with the Golgi apparatus, packaging and dispatching proteins to their destinations, whereas smooth ER plays a role in lipid and hormone production. Both types of ER have distinctive structures and functions and are essential for cellular operations.