An Hfr strain of E. coli that is pro thr * leu * lac " was "mated" with an F- strain that is pro thr lac. Conjugation was interrupted at 10, 13, 17, and 21 minutes with a kitchen blender, and the occurrence of donor alleles in F- recombinants was determined at each time point (by replica pla cells on minimal media plates that lacked proline, threonine, leucine, or lactose). The data showr below were obtained. % occurrence pro % occurrence thr* % occurrence leu* % occurrence lac Minutes phenotype phenotype phenotype phenotype 10 13 31 1 20
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.
Introduction
Genetic recombination is a process of exchange of genetic material between two different organisms that leads to the production of offspring. The offspring contains a combination of traits different from those of either parent. In bacteria, genetic recombination is characterized by the transfer of DNA from one organism (called donor) to another organism (called recipient). Genetic recombination occurs in three ways;
- Transformation - the uptake of exogenous (or foreign) DNA from the surrounding environment.
- Transduction - the virus-mediated transfer of DNA between bacteria. Viruses that infect the bacteria are called bacteriophage. It helps in transfer of genetic material.
- Conjugation - is the transfer of genetic material between two bacterial cells by direct cell-to-cell contact or by a bridge-like connection between two cells. This takes place through a structure called pilus. It is a parasexual mode of reproduction in bacteria.
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