Question

Describe lagging strand synthesis during DNA replication.

Answer 1

DNA polymerase a principal enzyme that synthesizes new DNA strand can work only in the 5' to 3' direction. As a result, the leading strand is synthesized continuously and the Lagging-strand replication is discontinuous as a series of short DNA fragments. This orientation problem of lagging strand is solved by the formation of short Okazaki fragments that are later linked together. As the helicase unwinds the DNA helix the primers are added periodically by the enzyme primase. DNA polymerase adds deoxyribonucleotides to these 3’ end of the primers in a 5’ to 3’ direction forming interspersed DNA and RNA strand. Following which RNase H enzyme removes the RNA primer and polymerase I fills in the necessary nucleotides between the Okazaki fragments Each of these short DNA fragments are subsequently joined together by DNA ligase to generate an uninterrupted strand of DNA.