Genetics of E. coli DNA Replication Mutants are powerful tools to study any biochemical process. But to be useful, the scienctist must be able to maintain mutant in a viable state. This poses a problem for mutants ofa essential processes such as DNA replication. If the mutated gene is re quired for DNA replication, it is obvious that the mutant will not last more than one generation. The use of conditional mutants has helped to solve this problem.
Conditional mutants express their mutant phenotype only under restricted conditons.
A popular form of conditional mutant is the temperature sensitive mutant. Temperature sensitive mutants only express their mutant phenotype at a temperature the organism normally does not confront. Many of these mutants are expressed at elevate d temperatures. Therefore the mutant will grow normally at the permissive temperature and express the mutant phenotype at the elevetated tempterature. The analysis of temperature-sensitive mutants of E. coli has defined a series of genes and their role in DNA synthesis.