This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
During DNA replication which bond breaks: 
Select and explain. 
A. Phosphodiester bonds, B. Phosphate bond, C. Hydrogen bond, D. Glycosidic bonds
C: Hydrogen bond
Answer: C: Hydrogen bond 
Explanation: Answer:c. Hydrogen bond When DNA replicates, a helicase enzyme "unzips" the double helix, breaking the hydrogen bonds that hold it together in the centerThe two strands of the double helix separate when hydrogen bonds between the paired bases are disrupted. Disruption can occur in the laboratory if the pH of the DNA solution is altered so that the nucleotide bases ionize, or if the solution is heated.