Prototrophy is often the phenotype selected to detecttransformants. Prototrophic cells are used for donorDNA extraction; then this DNA is cloned and the clonesare added to an auxotrophic recipient culture. Successfultransformants are identified by plating the recipientculture on minimal medium and looking for colonies.What experimental design would you use to make surethat a colony that you hope is a transformant is not, infact,a. a prototrophic cell that has entered the recipientculture as a contaminant?b. a revertant (mutation back to prototrophy by a secondmutation in the originally mutated gene) of theauxotrophic mutation?
Genetic Recombination
Recombination is crucial to this process because it allows genes to be reassorted into diverse combinations. Genetic recombination is the process of combining genetic components from two different origins into a single unit. In prokaryotes, genetic recombination takes place by the unilateral transfer of deoxyribonucleic acid. It includes transduction, transformation, and conjugation. The genetic exchange occurring between homologous deoxyribonucleic acid sequences (DNA) from two different sources is termed general recombination. For this to happen, an identical sequence of the two recombining molecules is required. The process of genetic exchange which occurs in eukaryotes during sexual reproduction such as meiosis is an example of this type of genetic recombination.
Microbial Genetics
Genes are the functional units of heredity. They transfer characteristic information from parents to the offspring.
Prototrophy is often the
transformants. Prototrophic cells are used for donor
DNA extraction; then this DNA is cloned and the clones
are added to an auxotrophic recipient culture. Successful
transformants are identified by plating the recipient
culture on minimal medium and looking for colonies.
What experimental design would you use to make sure
that a colony that you hope is a transformant is not, in
fact,
a. a prototrophic cell that has entered the recipient
culture as a contaminant?
b. a revertant (mutation back to prototrophy by a second
mutation in the originally mutated gene) of the
auxotrophic mutation?
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