How is the smooth endoplasmic reticulum (ER) different from the rough endoplasmic reticulum (ER)?

• A. The smooth ER is involved in lipid synthesis, while the rough ER is involved in protein synthesis.
• B. The smooth ER is responsible for DNA replication, while the rough ER is responsible for RNA transcription.
• C. The smooth ER is found only in plant cells, while the rough ER is found only in animal cells.
• D. The smooth ER contains ribosomes on its surface, while the rough ER does not.

Answer: (A)

Verified step by step guidance

1. Understand the basic structure and function of the endoplasmic reticulum (ER), which is an essential organelle in eukaryotic cells involved in the synthesis and transport of proteins and lipids.
2. Differentiate between the two types of ER: the smooth endoplasmic reticulum (smooth ER) and the rough endoplasmic reticulum (rough ER).
3. Recognize that the rough ER is characterized by the presence of ribosomes on its surface, which gives it a 'rough' appearance under a microscope. These ribosomes are the sites of protein synthesis.
4. Identify that the smooth ER lacks ribosomes on its surface, which gives it a 'smooth' appearance. It is primarily involved in lipid synthesis, metabolism of carbohydrates, and detoxification of drugs and poisons.
5. Clarify that both smooth and rough ER are found in both plant and animal cells, and neither is involved in DNA replication or RNA transcription, which occur in the nucleus.