Question

multiple choice question
the main function of the rough er is ____ synthesis while the main function of the smooth er is ____ synthesis.

protein; atp
lipid; protein
protein; dna
protein; lipid
lipid; dna

Explanation:

The rough endoplasmic reticulum (rough ER) has ribosomes on its surface, which are responsible for protein synthesis. The smooth endoplasmic reticulum (smooth ER) is involved in lipid synthesis (among other functions like detoxification). Let's analyze the options:

• Option 1: ATP synthesis is mainly by mitochondria, not smooth ER. Eliminate.
• Option 2: Lipid synthesis is smooth ER, protein is rough ER - this is reversed. Eliminate.
• Option 3: DNA synthesis occurs in the nucleus (and during replication), not smooth ER. Eliminate.
• Option 4: Rough ER does protein synthesis, smooth ER does lipid synthesis. This matches.
• Option 5: Lipid synthesis is smooth ER, but DNA synthesis is not smooth ER's function. Eliminate.

Answer:

D. protein; lipid (assuming the fourth option is labeled D, as per typical multiple - choice numbering where the fourth option is D. If the original options had different labels, adjust accordingly, but based on the content, the correct pair is protein for rough ER and lipid for smooth ER.)