Question

After DNA polymerase one has replaced the last nucleotide of the RNA primer with a DNA nucleotide, a break remains in the sugar phosphate backbone of the new DNA strand.

Answer 1

A break left in the sugar-phosphate backbone after RNA primer replacement is sealed by DNA ligase, which forms a covalent phosphodiester bond to ensure DNA structural integrity.

Step-by-step explanation:

After DNA polymerase I has replaced the RNA primer with DNA nucleotides during DNA replication, a break, or a 'nick', remains in the sugar-phosphate backbone of the lagging strand. This break is between the newly synthesized DNA and the adjacent DNA fragment. The enzyme DNA ligase rectifies this by forming a covalent phosphodiester bond between the 3'-OH end of one DNA fragment and the 5' phosphate of another, effectively sealing the nick in the sugar-phosphate backbone and ensuring the structural integrity of the DNA molecule.