Principles of Biochemistry (2+1)

7.2.1 DNA Replication

The two strands of the DNA double helix are a pair of templates, or patterns. During replication, the strands separate. Each can then act as a template for the synthesis of a new, complementary strand. The result is two daughter DNA molecules with base sequences identical to those of the parent double helix.

The details of replication

Under the influence of the enzyme DNA helicase, the DNA double helix unwinds, and the hydrogen bonds between complementary bases are broken. The base of the separated strands is no longer connected by hydrogen bonds. They can pair with free individual nucleotides present in the cell’s nucleus. The base pairing always involves C pairing with G and A pairing with T. This pairing process occurs one nucleotide at a time.

After a free nucleotide has formed hydrogen bonds with a base of the old strand(the template), the enzyme DNA polymerase verifies that the base pairing is correct and then catalyzes the formation of a new phosphodiester linkage between the nucleotide and the growing stand.

The DNA polymerase then slides down the strand to the next unpaired base of the template, and the same process is repeated.

Each of the two daughter molecules of double-stranded DNA formed in the DNA replication process contains one strand from the original parent molecule and one newly formed strand.

DNA replication is the process by which new DNA molecules are generated. It is the process by which DNA molecules produce exact duplicates of themselves. DNA molecules are the carriers of genetic information within a cell. Each time a cell divided, an exact copy of the DNA of the parent cell is needed for the new daughter cell.