Question

ΦΧ174 phage rolling circle replication provides model for leading strand synthesis.

Removal of the nicked strand (+):

Two kinds of activities are needed in vitro to convert double-stranded RF DNA to single-stranded DNA without synthesis of new DNA:
_____: separates the strands using ATP to provide the energy.
_____.

Answer 1

In the rolling circle replication of ΦΧ174 phage, helicase separates the DNA strands, utilizing ATP for energy. DNA ligase is essential for sealing nicks in the DNA. Bacteriophage replication mechanisms like this are leveraged in biotechnology.

Step-by-step explanation:

Understanding ΦX174 Phage Rolling Circle Replication

In the rolling circle replication model, an enzyme known as helicase is responsible for unwinding the DNA strand, using ATP as an energy source. This process commences with helicase creating a nick at the double-stranded origin (dso) and separating the strands. Another critical enzyme in this process is DNA ligase, which joins the Okazaki fragments on the lagging strand and can also seal nicks once the RNA primers are replaced with DNA on the leading strand.

Bacteriophage ΦΧ174 provides a model for this replication process. It involves a host cell's machinery, with DNA polymerase adding nucleotides to the leading strand in a 5' to 3' direction. Meanwhile, single-strand binding proteins stabilize the strands, and DNA gyrase relieves tension ahead of the replication fork.

For in vitro DNA manipulation using bacteriophage M13, which exhibits similar replication mechanisms, specific enzymes are added to replicate the replicative form (RF) without synthesizing new DNA. This demonstrates the practicability of understanding and harnessing biological processes for research and biotechnology applications.