Somatic cell hybridization is a method used to create recombinant DNA molecules. The technique involves combining DNA from two different sources, usually from different species. The resulting DNA molecule will contain genetic information from both parents. Somatic cell hybridization can be used to create transgenic animals or plants, which are organisms that contain foreign DNA.
The technique has also been used to determine which genes are present on which human chromosome. This was done by merging a mouse cell and human cell to form a heterokaryon, containing two separate nuclei in a common cytoplasm. Eventually the nuclei fuses to form a synkaryon. As culturing continues for many generations, eventually the human chromosomes are gradually lost while the full complement of mouse chromosomes remains. The few remaining chromosomes can then be studied to determine which ones are responsible for the expression of a gene product of interest. Consider the following question.
A panel of cell lines were created by human-mouse somatic-cell hybridization. Each cell line was examined for the presence of human chromosomes and for the production of three enzymes. The following results were
obtained. Based on the results, name the chromosomal locations of the genes encoding enzyme 1, enzyme 2, and enzyme 3 .
The table shows hybrid cell lines A, B, C, D and E, and which ones express the gene product. It also shows the human chromosomes that were retained. From this table you can conclude that the gene for enzyme 1 is located on chromosome 7. This is because whenever chromosome 7 is present, enxyme 1 is expressed. For the same resaon, the gene for enzyme 2 is located on chromosome 5, and the gene for enzyme 3 is located on chromosome x.