Question

Anybody wan't to explain the importance of covalent, hydrogen bonds in DNA replication?

Answer 1

The hydrogen bonds hold the two helixes of DNA together until it is time for them to replicate, during which the bonds are broken. When the nucleotides attach to the template to form the second strand, they use hydrogen atoms to bond with the template molecule, which is how replication occurs. Hydrogen bonds are covalent since there is no net positive or negative charge occurring and the bonds occur within DNA.

Answer 2

this is going to be a bit broad, but basically, covalent bonds hold the atoms in DNA together. Hydrogen bonds hold DNA together.

Answer 3

in a DNA duplex the nucleotides in a single strand are held together by phosphodiester bonds which are covalent bonds. The two strands are brought together to form a duplex through hydrogen bonding which are non-covalent bonds.

Hydrogen bonds being non-covalent are weaker than covalent bonds and hence can be broken easily. If the duplexes would have been held together by covalent bonds instead of hydrogen bonds then separating the two strands during replication would consume time making replication a slow process.
Moreover when the polymerase adds a nucleotide to the daughter strand the added nucleotide is held to the complementary nucleotide in the template strand by hydrogen bonding first after which the phosphodiester bond is formed. This gives polymerase time to check whether the inserted nucleotide is the right one or not via hydrogen bonding. If there is inappropriate hydrogen bonding between the inserted nucleotide and complementary nucleotide on the template strand then it is removed and the correct nucleotide is inserted.