A series of people are found to have difficulty eliminating

A series of people are found to have difficulty eliminating certain types of drugs from their bloodstreams. The problem has been linked to a gene X, which encodes the enzyme Y. Six people were tested with use of various techniques of molecular biology. Person A is a normal control, person B is asymptomatic but some of his children have the metabolic problem, and person C through F display the trait. Tissue samples from each person were obtained. Southern analysis was performed on the DNA after digestion with the restriction enzymes HindIII. Northern analysis of mRNA also was done. In both types of analysis, the gels were probed with labeled X cDNA. Finally, a western blot with an enzyme-linked monoclonal antibody was used to test for the presence of protein Y. The results are shown here. Why is person B without symptoms? Suggest possible defects on other people.

Solution

From the results it is clear that there are two copies of gene X. So only we are getting 2 bands for gene X for B in sourthern blot. One copy of the genes is mutated and other is fine hence normal enzyme is produced. So B is asymptomatic. When the 2 copies of genes passes to next generation , the ones which receive single mutant copy gets affected. Person C has gene but the molecular weight is less . So the gene is small and no functional gene is transcribed (transcribed) or translated (western blot). Person D has a normal-size of the gene but no RNA or protein. There may be a mutation in the gene so that transcription dint take place. Person E has a normal copy of the gene that is transcribed, but no protein is made, which suggests that a mutation prevents translation. Person F has a normal amount of protein but still displays has the trait. So we can conclude that due to the mutation the activity of the enzyme is lost. so functional protein is not produced in F.