In the context of eukaryotic cells, what are polyribosomes?

• A. Clusters of ribosomes bound to a single mRNA molecule
• B. Complexes of DNA and protein found in the nucleus
• C. Membrane-bound organelles involved in protein synthesis
• D. Structures responsible for lipid synthesis

Answer: (A)

Verified step by step guidance

1. Understand that polyribosomes, also known as polysomes, are related to protein synthesis in eukaryotic cells.
2. Recall that ribosomes are the cellular structures where proteins are synthesized, and they can be found either free in the cytoplasm or bound to the endoplasmic reticulum.
3. Recognize that a single mRNA molecule can be translated by multiple ribosomes simultaneously, forming a structure known as a polyribosome or polysome.
4. Differentiate polyribosomes from other cellular structures: they are not complexes of DNA and protein (which are chromatin) nor are they membrane-bound organelles (like the endoplasmic reticulum).
5. Conclude that polyribosomes are clusters of ribosomes bound to a single mRNA molecule, allowing for efficient protein synthesis.