DNA Replication

DNA Replication The complementary base pairing allows the DNA to be used as a template during replication. DNA replication is simply making a copy of the DNA. We call this semi-conservative replication: the new strand contains one strand from the parent helix and one new strand.

Steps DNA Helicases (enzymes) break the hydrogen bonds between nucleotides allowing the 2 strands to separate. Other proteins attach to keep the strands from recoiling The areas where the DNA is separated is called a replication fork. DNA polymerases move along each strand of DNA from the 5’ end to the 3’ end adding nucleotides to the exposed bases according to the base pairing rules (A-T/C-G). DNA polymerase continues until the entire DNA is copied.

The Result… 2 new strands of DNA that are identical to the beginning DNA strand

DNA Replication Animation

Checking for Errors DNA polymerase has a “proof reading” role! It can only add a new nucleotide if the one before it is correct. If it is not correct, the DNA polymerase has to back track and fix the wrong nucleotide before it can continue.

The speed of Replication DNA isn’t replicated by 1 DNA polymerase starting at one end and copying the entire strand. If it was replicated this way, it would take 33 days! Instead, we replicate our DNA in sections (about 100 sections are being replicated at the same time). This allows for a single strand of DNA to be copied in about 8 hours.