The diagram shows a length of template DNA and three okazaki

The diagram shows a length of template DNA and three okazaki fragments of the lagging strand. The RNA primers have not yet been removed. Which okazaki fragment was synthesized first, the one on the left, in the middle, or to the right? Before the primer of the left Okazaki fragment can be removed by DNA polymerase I and the gap can be filled in, is it necessary for the middle okazaki fragment to have already been synthesized? Explain why or why not.

Solution

a. the right okazaki fragment will be synthesised first since the DNA polymerase thaa catalyzes the reaction works in the 5\'-3\' direction thus the overall DNA replication is moving towards the fork in the 5\' end

b. yes the middle okazaki fragment must already have been synthesised since the DNA polymerase I needs a 3\' end to add or attach the replacement nucleotides once whe it has removed the primer