DNA Replication The DNA molecule unwinds Weak __________ bonds between base pairs break allowing the two stands to separate (‘unzip’). Their bases are now exposed at a Y-shaped replication fork The enzyme DNA polymerase controls the sugar phosphate of the new nucleotides into the new DNA strand. It can only add nucleotides to a pre-existing chain, i.e. where there is a primer a – short series of nucleotides at the 3’ end of the parental DNA to be replicated. Synthesis occurs in a 5’ to 3’ direction (on the new strand) The DNA nucleotides will then bind to complementary partners on the template strand (following the base pairing rule) at the 3’ end. DNA polymerase brings about the formation of the complementary sugar-phosphate bond and the nucleotides. DNA polymerase is only able to add nucleotides to the free 3’ end of a growing strand. Therefore the DNA template strand has to be replicated in fragments (called Okazaki fragments) each starting at the 3’ end of a primer. Once the fragments are complete the primer is replaced by DNA They are then joined together by an enzyme called ligase. This type of fragment formation is called discontinous.
DNA Replication The DNA molecule unwinds Weak __________ bonds between base pairs break allowing the two stands to separate (‘unzip’). Their bases are now exposed at a Y-shaped replication fork The enzyme DNA polymerase controls the sugar phosphate of the new nucleotides into the new DNA strand. It can only add nucleotides to a pre-existing chain, i.e. where there is a primer – a short series of nucleotides at the 3’ end of the parental DNA to be replicated. Synthesis occurs in a 5’ to 3’ direction (on the new strand) The DNA nucleotides will then bind to complementary partners on the template strand (following the base pairing rule) at the 3’ end. DNA polymerase brings about the formation of the complementary sugar-phosphate bond and the nucleotides. DNA polymerase is only able to add nucleotides to the free 3’ end of a growing strand. Therefore the DNA template strand has to be replicated in fragments (called Okazaki fragments) each starting at the 3’ end of a primer. Once the fragments are complete the primer is replaced by DNA They are then joined together by an enzyme called ligase. This type of fragment formation is called discontinous.