What is a plasmid?

PLASMIDS can be found in many bacteria and are small rings of DNA with a limited number of genes. Plasmids are not essential for the survival of bacteria but can make life a lot easier for them. Whilst all bacteria - no matter which species - will have their bacterial chromosome with all the crucial hereditary information of how to survive and multiply, they invented a tool to exchange information rapidly. If one likens the chromosome to a bookshelf with manuals and handbooks, and a single gene to a recipe or a specific building instruction, a plasmid,could be seen as a pamphlet. Plasmids self-replicate and are thus easily reproduced and passed around. Plasmids often contain genes for antibiotic resistance. This type of information which can easily be passed on, can be crucial to bacterial strains which are under attack by drugs and is indeed a major reason for the quick spread of antibiotic resistance.