6. (4pts) Some people can taste the bitter taste of PTC (phenylthiocarbamide) and some don\'t.
Usually is also related to increased tasting of spicy food, etc. Simple PCR tests were developed
to confirm ability/inability to taste PTC. The SNP at position 785 is useful for determining PTC
genotype since the common taster sequence in this region forms a Fnu4H1 restriction enzyme
digestion (cut) site. In contrast, in the common nontaster allele, there is a T at position 785
(instead of C785), which eliminates this restriction enzyme digestion (cut) site. A polymerase
chain reaction (PCR) generates a 303 base pair (bp) DNA fragment with primers amplifying the
SNP region . Restriction digestion of this PCR product with Fnu4H1 will yield one 303 bp
fragment for the common nontaster allele (because the restriction enzyme cut site is not present)
and two shorter fragments (64 bp and 239 bp) for the common taster allele Using the gel picture
below, explain which tested individuals have tasters or non- tasters genotypes
Solution
Non taster allele shows one band at 303 bp. Hence the lane 2, 5 and 10 shows the individuals
with non taster allele.
Taster allele has restriction site and hence has 2 fragments 63 and 239 bp. Hence the lanes 3,4,7
and 9 indicates indivifual with taster allele.
Usually is also related to increased tasting of spicy food, etc. Simple PCR tests were developed
to confirm ability/inability to taste PTC. The SNP at position 785 is useful for determining PTC
genotype since the common taster sequence in this region forms a Fnu4H1 restriction enzyme
digestion (cut) site. In contrast, in the common nontaster allele, there is a T at position 785
(instead of C785), which eliminates this restriction enzyme digestion (cut) site. A polymerase
chain reaction (PCR) generates a 303 base pair (bp) DNA fragment with primers amplifying the
SNP region . Restriction digestion of this PCR product with Fnu4H1 will yield one 303 bp
fragment for the common nontaster allele (because the restriction enzyme cut site is not present)
and two shorter fragments (64 bp and 239 bp) for the common taster allele Using the gel picture
below, explain which tested individuals have tasters or non- tasters genotypes
Solution
Non taster allele shows one band at 303 bp. Hence the lane 2, 5 and 10 shows the individuals
with non taster allele.
Taster allele has restriction site and hence has 2 fragments 63 and 239 bp. Hence the lanes 3,4,7
and 9 indicates indivifual with taster allele.
