Question

What is happening to the DNA molecule in the figure?(Explain the first step in DNA replication)

Answer 1

Answer:

As this is DNA replication, this is the unwinding process

Explanation:

In DNA replication, the parent DNA to be replicated is unwound to enable access of the replication machinery (replisome) to this genetic material. The origin of replication will be identified first, which in the prokaryotes is only one, and in the eukaryotes, we have many. This sites are recognized by specific sequences on the genome. after this, melting of the DNA occurs at this origin creating a replication bubble and two replication forks. This  allows for the unwinding of the DNA by the enzyme Helicases in the direction of the replication fork. Another enzyme present in this step is also the single strand binding proteins (SSB). These proteins function in the prevention of re-annealing of the unwound DNA strand by attaching themselves to each strands. Another enzyme called the topoisomerases also function here by reducing the torque (twisting) produced upstream of the replication fork as result of DNA unwinding. An example is the gyrase.