Question

question 24
1 pts
replication of dna cannot begin until
covalent bonds between sugar molecules are broken.
phosphate bonds between nucleotides are broken.
hydrogen bonds between complementary bases are broken.
hydrogen bonds between nucleotides in one strand are broken.

Explanation:

DNA replication starts with the unwinding of the double - helix structure. The two strands of DNA are held together by hydrogen bonds between complementary base pairs (A - T and G - C). These hydrogen bonds need to be broken to separate the two strands, which then serve as templates for the synthesis of new complementary strands. Covalent bonds between sugar molecules (in the sugar - phosphate backbone) and phosphate bonds between nucleotides are not the ones that need to be broken for the start of replication. Also, hydrogen bonds between nucleotides in one strand do not exist in the context of DNA structure (nucleotides in a single strand are linked by phosphodiester bonds, not hydrogen bonds).

Answer:

hydrogen bonds between complementary bases are broken.