MDCAT Biology MCQ #850

During the elongation of a DNA strand, the 3' hydroxyl group of the existing chain attacks the incoming nucleotide. Which part of the incoming nucleotide is targeted?

MDCAT Biology MCQ #850

  1. Question 1

    Q1. During the elongation of a DNA strand, the 3' hydroxyl group of the existing chain attacks the incoming nucleotide. Which part of the incoming nucleotide is targeted?

    • A) Nitrogenous base
    • B) 5' phosphate group
    • C) 2' carbon atom
    • D) Pentose ring oxygen

    Answer: 5' phosphate group

    Explanation: Phosphodiester bonds form between the 3' OH of the chain and the 5' phosphate of the incoming nucleotide. Nitrogenous bases are involved in hydrogen bonding.