8. (3 pts) People with the recessive disease, Purple DNA Tongue Syndrome, are unable to make the enzyme + NA Blue Pigment Decolorase (BPD). You isolate mRNA from a person (P) afflicted with the disease and from a normal person (N) and do the following: DNA i. Mix excess P mRNA with cloned DNA carrying the BPD +PORNA gene and, separately, mix mRNA with the same DNA. ii. Raise the temperature of the mixtures, and then cool to allow RNA-DNA hybridization to occur. iii. For each mixture, locate by electron microscopy heteroduplex molecules. "Heteroduplex" here refers to hybrid molecules in which one strand is mRNA and the other BPD DNA. The cartoon at the right is supposed to be what you see by electron microscopy. Double- stranded regions are represented by thick lines, and single-stranded regions are represented by thin lines. a. The single-stranded loops are composed of which: RNA or DNA? Why? b. What is the single-stranded region at one end of the heteroduplex? c. What is the molecular cause of Purple Tongue Syndrome?