Initiation Phase
DNA replication begins when enzymes unwind and separate the double helix at specific points called origins of replication. Helicase enzymes break hydrogen bonds between base pairs, creating a replication fork with two separate strands. Proteins stabilize the separated strands while other enzymes prepare for DNA synthesis. This carefully coordinated process ensures accurate copying of genetic information.
Synthesis Process
DNA polymerase enzymes add new nucleotides to growing DNA strands, following base-pairing rules: adenine with thymine, cytosine with guanine. The leading strand forms continuously in the direction of fork movement, while the lagging strand produces in short segments called Okazaki fragments. Multiple enzymes work together to join these fragments and ensure accurate replication.
Error Checking
Several proofreading mechanisms verify copying accuracy during replication. DNA polymerase checks each new base pair, removing and replacing incorrect nucleotides. Additional repair enzymes scan completed DNA for errors and fix mistakes. This multi-level quality control system maintains genetic integrity, with an error rate of approximately one mistake per billion base pairs. Shutdown123