MDCAT Biology MCQ #982

MDCAT Biology MCQ #982

1. Question 1

   Q1. During RNA synthesis, a phosphodiester bond is formed. Which specific mechanism describes the directionality of this bond formation?

   • A) Attachment of phosphate to the 2' carbon of ribose
   • B) Reaction between 3' hydroxyl and 5' phosphate groups
   • C) Hydrogen bonding between the 5' and 3' ends
   • D) Esterification of the nitrogenous base to the phosphate

   Answer: Reaction between 3' hydroxyl and 5' phosphate groups

   Explanation: New nucleotides are added when the 3' -OH group of the existing chain attacks the 5' phosphate of the incoming nucleotide.