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Since all polymorphism has a genetic basis, genetic polymorphism has a particular meaning: Genetic polymorphism is the simultaneous occurrence in the same locality of two or more discontinuous forms in such proportions that the rarest of them cannot be maintained just by recurrent mutation or immigration, originally defined by Ford (1940).
Pleomorphism has been observed in some members of the Deinococcaceae family of bacteria. [1] The modern definition of pleomorphism in the context of bacteriology is based on variation of morphology or functional methods of the individual cell, rather than a heritable change of these characters as previously believed.
Polymorphisms can be identified in the laboratory using a variety of methods. Many methods employ PCR to amplify the sequence of a gene. Once amplified, polymorphisms and mutations in the sequence can be detected by DNA sequencing, either directly or after screening for variation with a method such as single strand conformation polymorphism analysis.
The OMIM database describes the association between polymorphisms and diseases (e.g., gives diseases in text form) dbSAP – single amino-acid polymorphism database for protein variation detection [59] The Human Gene Mutation Database provides gene mutations causing or associated with human inherited diseases and functional SNPs
Mutations that lead to antigenic differences can be traced to the biochemical nature of the amino acid substitutions as well as the location of the mutation in the domain III. For example, substitutions at different amino acids results in varying levels of neutralization by antibodies.
Bacterial conjugation is the transfer of genetic material between bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. Bacterial conjugation has been extensively studied in Escherichia coli , but also occurs in other bacteria such as Mycobacterium smegmatis .
SNPs are one of the most common types of genetic variation. An SNP is a single base pair mutation at a specific locus, usually consisting of two alleles (where the rare allele frequency is > 1%). SNPs are found to be involved in the etiology of many human diseases and are becoming of particular interest in pharmacogenetics.
Bacterial morphological plasticity refers to changes in the shape and size that bacterial cells undergo when they encounter stressful environments. Although bacteria have evolved complex molecular strategies to maintain their shape, many are able to alter their shape as a survival strategy in response to protist predators, antibiotics, the immune response, and other threats.