Question

The following family tree contains many members who had or have the disease "Emseebeeitis" (indicated by the shaded circles and squares) (circles represent females and squares represent males). Those individuals who are healthy are indicated by unshaded figures. Those individuals who died have a slash mark. Those people who are still alive (1-16) were analyzed for a particular microsatellite "BH106". 1 2 3 DNA was isolated from each surviving member and microsatellite "BH106" was amplified by PCR and products were separated by agarose gel electrophoresis. The gel is shown below with each lane number representing the family member indicated by numbers in the family tree above. The letters indicated on the left side represent the form or "allele" of microsatellite "BH106". 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 - - - - - - A B - - - - - - C - - - - D - - - - - - - - E - - A. Most of the individuals produced two bands in the agarose gel. Why? B. Why does individual #7 only produce one band in the agarose gel? C. Which "allele" of microsatellite "BH106" is closely linked to the defective gene that causes the disease "Emseebeeitis"? Answer options: A, E, D, C, or B? D. Which of the following diseases might show a similar pattern of inheritance? a. Phenylketonuria b. Tay-Sachs c. Cystic fibrosis d. Sickle cell anemia e. Hereditary non-polyposis colorectal cancer E. Individual #14 does not follow the predicted pattern of inheritance of "Emseebeeitis". Give two possible explanations for this?

Answer 1

A) Every individual has two homologous chromosome. There are two double stranded DNA. In this way two allele are found in an individual for BH106. During PCR, two product are synthesised for each allele. And give two bands in the gel.

B) Individual 7 produces single band because individual 7 is homozygous for BH106 and produce same length of DNA and when run in the gel electrophoresis. Both DNA occupies same region and give appearance of one band.

C) D gene is responsible for disease. In the gel, you I'll find that each individual will have atleast one D band.

D) This is the case of autosomal dominant disease.

Right option is e ( Herediatry non polyopsis colorectal disorder)

E) Individual 14 does not follow predicted behavior because of following reasons:

* The crossing over occur between homologous chromosome will produce allele which makes the D allele in wild type form in individual 14' s mother. When this D gene pass to 14 individual, there is no disease found.

* Mutation occur in D gene which convert it into wild type form.