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R-factor, or resistance factor, are plasmids that allow specific bacteria to gain resistance against antibiotics. They are mostly available in a set of genetic codes which can transfer themselves from one cell to another of a bacterium via means of conjugation or non-conjugation. Through bacterial conjugation, many r-factors can pass from bacterium to another. R factor is accountable for coding of antimicrobial resistance against specific drugs. Moreover, they often code restriction for more than a single antibiotic, up to eight different resistances at times. The standard means of spreading antimicrobial resistance among various bacterial species, chromosomes, etc. occur via conjugation. Define PlasmidPlasmids are small, extra-chromosomal structure found in bacteria that can replicate itself. These circular molecules of DNA have a double-stranded format, and they are also found in multi-cellular organisms and archaea. R plasmid is a DNA molecule that grants bacterial resistivity to one antibiotic or more. It comprises of two components primarily – a resistance transfer factor (RTF) and resistance determinants. RTF is a necessary factor responsible for the transmission of plasmids among bacteria, and r-determinants are genetic codes promoting antibiotic resistivity. What are the Types of Plasmids?
Structure of Resistance PlasmidThe resistance plasmid can be said to resemble a circular structure of DNA fragments, and its length varies in the spectrum of 80-95 kb and constitutes of the larger segment of a factor known as the R-RTF or Resistance Transfer Factor molecules. This plasmid is known to be majorly homologous to the F factor and contains quite like genes. It also constitutes a gene known as the fin 0 gene that restrains the task of transferring of the operon. These R factors come in varying sizes and also the kinds of resistance they offer to drugs. The R determinant is smaller in size as compared to the RTF. The RTF as well as the R determinants bind to develop a single unit and are split up from one another by the presence of IS 1 elements on both the sides. The presence of these IS 1 elements encourages the interchange of R determinant amongst the variants of R-RTF units present. Functions of Resistance PlasmidFollowing are the functions of the resistance plasmid -
Horizontal Gene TransferBacteria which consists of the F factors, can build a sex pilus which encourages the transmission of the horizontal gene between the bacteria, which is the donor and the bacteria, which is the recipient. The resistance to an antibiotic can quickly and without much hassle and expand amongst the rest of the bacterial community as well. This is because the F factor is present in several R factors too. Due to the presence of the gene known as the RTF or the Resistance Transfer Factor, several R factors can also be consumed by the DNA through the process of transduction or transformation. Fun Fact There are more than 100 types of antibiotic drugs! Some most commonly used antibiotics are amoxicillin, azithromycin, penicillin, streptomycin, etc. Wrack Your Brains Here are specific questions on r factor and its functioning. Use your knowledge to crack them.
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The resistance transfer factor (RTF) is about 80 kb in length and carries genes for autonomous replication, conjugation and resistance to ampicillin. The RTF is largely homologous to F factor and contains similar genes.
What are R plasmids and why are they important?R-Factor is also called as the resistance factors or resistance plasmids. They are a group of conjugative plasmids which promotes the bacterial host resistance to specific antibiotics and to some metal ions, including sulphonamide, streptomycin, tetracycline, arsenic, cadmium, mercury, etc.
What is F factor R Factor?F factors contain information for a restriction system for phages φII and T7. Cells containing R factors are sensitive to these phages. Furthermore, R(fi+) factors do not repress the F factor φII restriction system in cells containing both an R(fi+) factor and an F factor.
What is the function of R plasmids in bacteria?Resistance or R plasmids contain genes that help a bacterial cell defend against environmental factors such as poisons or antibiotics. Some resistance plasmids can transfer themselves through conjugation. When this happens, a strain of bacteria can become resistant to antibiotics.
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