Question

Sketch a replication fork of bacterial DNA in which one strand is being replicated discontinuously and the other is being replicated continuously. List six different enzyme activities associated with the replication process, identify the function of each activity, and show where each would be located on the replication fork. In addition, identify the following features on your sketch: DNA template, RNA primer, Okazaki fragments, and single-stranded DNA binding protein.

Answer 1

Answer:

DNA Helicase is the enzyme that unwinds the double-stranded DNA into two single strands forming a replication fork.

DNA topoisomerase II or Gyrase is the enzyme responsible for relieving or relaxing the topological stress caused by the unwinding of DNA double strands.

DNA polymerase III is the primary replication enzyme. It is responsible for adding deoxyribonucleotides to the RNA primer both in the continuous or leading strand synthesis as well as in the discontinuous or lagging strand synthesis of DNA.

Primase is the enzyme responsible for the synthesis of the RNA primer (a short segment of RNA) to which deoxyribonucleotides are added.

DNA polymerase I is responsible removing and replacing the RNA primers with DNA in the newly DNA strands.

DNA Ligase is the enzyme responsible for sealing the gaps in the DNA due to broken phosphodiester bonds after the removal of the RNA primer.

Explanation:

The sketch of the replication fork of bacterial DNA showing where one strand is being replicated discontinuously and the other is being replicated continuously, as well as the different enzymes involved and their location of activity is found in the attachment below.

DNA replication occurs in the 5' to 3' direction by DNinA polymerases.

Continous DNA replication occurs in same direction as the direction as the replication fork, in the 5' to 3' direction.

The discontinuous replication occurs in fragments of DNA known as Okazaki fragments which are then ligated by DNA ligase.