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MDCAT Biology QUESTION #11377
Question 1
A group of ribosomes attached to mRNA is known as a polysome and the attachment is controlled by:
  • $Mg^{2+}$ ions✔️
  • $K^+$ ions
  • $Ca^+$ ions
  • $Na^+$ ions
Correct Answer Explanation
$Mg^{2+}$ (magnesium) ions are essential for stabilizing the association between ribosomes and mRNA in polysomes (polyribosomes). Magnesium ions neutralize the negative charges of the ribosomal RNA and mRNA backbone, enabling multiple ribosomes to attach simultaneously to a single mRNA for efficient protein synthesis.