Diagram a replication fork in bacterial DNA and label the following structures or molecules.

a. DNA pol III
b. helicase
c. RNA primer
d. origin of replication
e. leading strand (label its polarity)
f. DNA pol I
g. topoisomerase
h. SSB protein
i. lagging strand (label its polarity)
j. primase
k. Okazaki fragment

Key Concepts

DNA Replication

DNA replication is the biological process by which a cell duplicates its DNA before cell division. It involves unwinding the double helix structure and synthesizing new strands complementary to the original ones. Key enzymes, such as DNA polymerases, helicases, and primases, play crucial roles in this process, ensuring accurate and efficient replication.

Leading and Lagging Strands

During DNA replication, the leading strand is synthesized continuously in the direction of the replication fork, while the lagging strand is synthesized discontinuously in short segments called Okazaki fragments. This difference arises because DNA polymerase can only add nucleotides in a 5' to 3' direction, necessitating a more complex mechanism for the lagging strand.

Key Enzymes in DNA Replication

Several key enzymes are essential for DNA replication: helicase unwinds the DNA double helix, DNA polymerase synthesizes new DNA strands, primase lays down RNA primers to initiate synthesis, and topoisomerase alleviates the tension created ahead of the replication fork. Each enzyme has a specific function that contributes to the overall fidelity and efficiency of DNA replication.