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

The picture illustrated depicts the DNA replication and the first step is the unwounding process.

DNA replication simply means the process through which a double-stranded DNA molecule will be copied in order to produce two identical DNA molecules.

In DNA replication, it should be noted that the parent DNA is replicated to enable access of the replication machinery to the genetic material. In the diagram, the origin of replication will be identified first. The first step in DNA replication will be the unzipping of the double helix structure of the DNA by helicase.

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As this is DNA replication, this is the unwounding 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-anealing 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 unwounding. An example is the gyrase

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.