What provides energy for DNA elongation?

What provides energy for DNA elongation?

• A. Light energy
• B. Heat energy
• C. Hydrolysis of ATP
• D. Breaking the phosphate bonds of the 2 phosphates attached to each new nucleotide

Answer: (D)

DNA elongation is powered by the energy stored in the incoming nucleotide triphosphate. As the nucleotide is added, the 3' end of the growing strand attacks the alpha phosphate of the dNTP, forming a new phosphodiester bond and releasing pyrophosphate (the two terminal phosphates are cleaved off). The subsequent hydrolysis of pyrophosphate to two inorganic phosphates provides a large energy boost that drives the reaction forward, making bond formation favorable. So the energy comes from breaking the phosphate bonds of the two trailing phosphates on the incoming nucleotide, not from light, heat, or direct ATP hydrolysis.

DNA elongation is powered by the energy stored in the incoming nucleotide triphosphate. As the nucleotide is added, the 3' end of the growing strand attacks the alpha phosphate of the dNTP, forming a new phosphodiester bond and releasing pyrophosphate (the two terminal phosphates are cleaved off). The subsequent hydrolysis of pyrophosphate to two inorganic phosphates provides a large energy boost that drives the reaction forward, making bond formation favorable. So the energy comes from breaking the phosphate bonds of the two trailing phosphates on the incoming nucleotide, not from light, heat, or direct ATP hydrolysis.