Col-plasmids. They are double stranded and mostly circular. A plasmid is a small, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. Apart from the virulence gene, plasmids have also been shown to carry other important elements that enhance transmission and maintenance. Degradative plasmids. For this reason, they are larger in size but low in numbers. INTRODUCTION OF PLASMIDS, THEIR IMPORTANCE AND TYPES Plasmids are transferable extrachromosomal DNA molecules capable of autonomous replication. Plasmids can be classified into various categories, but the most commonly known classification is based on their functions. Types of plasmids. Cloning vectors tend to be very simple, often containing only a bacterial resistance gene, origin and MCS. Allow bacterial mating. Allow bacteria to be resistant to specific antibiotics and toxins, through genes that confer resistance. The average size of the pUT-type plasmids was 68.4 kb, which was larger than Rep20 type plasmids and smaller than RepABC-type plasmids (Figure 3C). It usually occurs naturally in bacteria and is some times found in eukaryotic organisms e.g. • Resistance Plasmids (R PLASMID ) – Contain genes that can build resistance to antibiotics or poisons. Fertility plasmid. Enable bacteria to digest and utilize certain substances. Plasmids, depending on their transmissibility property are of three types: 1.Transmissible plasmid : They can be transferred from cell to cell by the process of genetic transfer like conjugation, hence also known as conjugative plasmid. The combination of elements often determines the type of plasmid. The Saccharomyces cerevisiae. According to this, they are divided into 5 different types – fertility plasmids, resistance plasmids, col plasmids, virulence plasmids and metabolic or degradative plasmids. Below are some common plasmid types: Cloning Plasmids - Used to facilitate the cloning of DNA fragments. Most of the plasmids classified into these three Rep types were in Alphaproteobacteria (Table S1), whereas two pUT1-type plasmids and six RepABC-type plasmids were found in other classes or phyla (Table S1). PLAY. Types of plasmids. Plasmids with different origins of replication and different replication genes are able to inhabit the same bacterial cell and are considered compatible (left). During cell division, both types of plasmid replicate; therefore, each daughter cell will inherit both plasmids, just like the mother cell. Resistance plasmids. STUDY. TYPES OF PLASMIDS 1.on the basis of function • Fertility Plasmids ( F PLASMID ) – carry the fertility genes (tra-genes) for conjugation, the transfer of genetic information between two cells. Like other types of plasmids, virulence plasmids can also be transmitted from one bacterium to another.