Homework SourseYou prepare bacterial cell extracts by lysing the cells and
Solution
Ans.) In the given question, the DNA is a plasmid with a small, double stranded circular and with the ability to replicate independently. They are also called replicons, a unit of DNA capable of replicating autonomously within a suitable host.
To replicate independently, it needs an origin of replication with a number of elements, such as the gene for plasmid-specific replication initiation protein called as Rep, several repeating units known as iterons, DnaA boxes, and an adjacent AT-rich region. The smaller plasmid uses replicative enzymes of host to make copies of themselves, whereas the larger plasmids must carry their own gene specific for the replication.
Plasmid always carries at least one gene which is beneficial for its host. Plasmids are generally circular, but linear plasmids are also found. These linear plasmids require specialized mechanisms to replicate their ends.
DNA replication in plasmid can be divided into three stages; initiation, elongartion and termination. Initiation is catalyzed by one or a few plasmid-encoded initiation proteins that recognize plasmid-specific DNA sequences and decide the point from which replication starts (the origin of replication).
Elongation is carried out basically by DNA polymerase III holoenzyme and, in few cases, by DNA polymerase I at initial stage, with the input of other host protein that form the replisome.
Termination of plasmid DNA replication ( theta-type replication) determined by molecular interactions at particular sequences.There are several sequence found like ter sequence to arrest the replication process.
