The discovery of plasmids is credited to Joshua Lederberg and Esther Lederberg in the 1950s. They identified plasmids as small, circular DNA molecules that are found in bacteria and can replicate independently of chromosomal DNA.
A helper plasmid is one that allows for the beginning of replication and transfer of other plasmids from a donor to a recipient. Without a helper plasmid, transposons will not be expressed in the recipient.
Recombiant DNA
In the production of a recombinant plasmid, the DNA of interest (insert) and the plasmid vector are both cut with restriction enzymes to create compatible ends. These cut fragments are then ligated together using DNA ligase to produce the recombinant plasmid.
A plasmid is considered recombinant when it contains DNA sequences from two different sources that have been artificially combined, often through genetic engineering techniques like restriction enzyme digestion and ligation. This results in a plasmid with modified or additional genetic material compared to its original form.
If the plasmid were cut at more than one site, it could result in the fragmenting of the plasmid into smaller pieces. This could lead to difficulties in maintaining the integrity of the plasmid during cloning processes, affecting the stability and functionality of the plasmid. Additionally, it may disrupt the insertion of foreign DNA or hinder the replication of the plasmid in host cells.
The Ti plasmid was discovered by Mary-Dell Chilton in the 1970s while she was studying Agrobacterium tumefaciens, a bacterium that causes plant tumors. This discovery led to the development of techniques for genetic engineering in plants.
R-plasmid
TOL plasmid
A plasmid is an extra-chromosomal element. Strictly speaking, it is not a part of the bacterial mail genome. Plasmids, when first discovered in bacteria, were observed to contain genes that confer special features to the bacteria (like drug resistance). Also, a plasmid is capable of autonomous replication, which means it has its own origin of replication and does not have to wait for the bacterial genome to be replicated. When a foreign gene is inserted into a plasmid, the plasmid has to be transformed into the bacteria. Once transformed, the cDNA in the plasmid is able to replicate every time the plasmid replicated. This does not have any affect on the normal functioning of the bacteria. The organism is merely being used to make copes of the foreign gene and/or harvest an important protein product.
You can determine if your bacteria contain a plasmid by performing a plasmid extraction followed by gel electrophoresis to visualize the presence of plasmid DNA. Other methods include PCR amplification of plasmid-specific sequences or using molecular biology techniques like restriction enzyme digestion to confirm the presence of a plasmid.
Plasmid is extrachromosomal DNA capable of self replication.
A plasmid which encodes genes for its own transfer.
A helper plasmid is one that allows for the beginning of replication and transfer of other plasmids from a donor to a recipient. Without a helper plasmid, transposons will not be expressed in the recipient.
Recombiant DNA
You can have a maximum of 8 plasmid slots.
The plasmid is found in prokaryotic cells.
In the production of a recombinant plasmid, the DNA of interest (insert) and the plasmid vector are both cut with restriction enzymes to create compatible ends. These cut fragments are then ligated together using DNA ligase to produce the recombinant plasmid.