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conjugative - mediate DNA transfer through conjugation and therefore spread rapidly among the bacterial cells of a population; e.g., F plasmid, many R and some col plasmids. nonconjugative - do not mediate DNA through conjugation, e.g., many R and col plasmids. The pBR322 plasmid is one of the first plasmids widely used as a cloning vector.
A plasmid is a small, extrachromosomal DNA molecule within a cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria ; however, plasmids are sometimes present in archaea and eukaryotic organisms .
Minicircles are small (~4kb) circular plasmid derivatives that have been freed from all prokaryotic vector parts. They have been applied as transgene carriers for the genetic modification of mammalian cells, with the advantage that, since they contain no bacterial DNA sequences, they are less likely to be perceived as foreign and destroyed.
Drawing showing the difference between a circular DNA chromosome (a plasmid) with a secondary helical twist only, and one containing an additional tertiary superhelical twist superimposed on the secondary helical winding. In nature, circular DNA is always isolated as a higher-order helix-upon-a-helix, known as a superhelix. In discussions of ...
Circular DNA is DNA that forms a closed loop and has no ends. Examples include: Plasmids, mobile genetic elements; cccDNA, formed by some viruses inside cell nuclei;
Plasmids: These are generally circular extrachromosomal DNA molecules that replicate and are transmitted independently from chromosomal DNA. These molecules are present in prokaryotes (bacteria and archaea) and sometimes in eukaryotic organisms such as yeast. Fitness of a plasmid is determined by its mobility.
Rolling circle replication produces multiple copies of a single circular template. Rolling circle replication (RCR) is a process of unidirectional nucleic acid replication that can rapidly synthesize multiple copies of circular molecules of DNA or RNA, such as plasmids, the genomes of bacteriophages, and the circular RNA genome of viroids.
A circular chromosome is a chromosome in bacteria, archaea, mitochondria, and chloroplasts, in the form of a molecule of circular DNA, unlike the linear chromosome of most eukaryotes. Most prokaryote chromosomes contain a circular DNA molecule. This has the major advantage of having no free ends to the DNA.