maintain taster and non-taster alleles in humans conferring an advantage to heterozygotes perhaps by increasing the repertoire of bitter toxins that can be detected through the diverse receptors (Wooding 2004). et al., Experimental Overview Your ability to taste thiourea-containing compounds will be evaluated by examining both your phenotype and genotype. First, using your self-knowledge of the foods you like and dislike, you will form a testable hypothesis (Taster or Non-taster). Once you have your hypothesis you will determine your genotype by; isolating your genomic DNA (Day 1), PCR amplifying the genetic area of interest using the dCAPs method (Day 2), and using two different methods (restriction enzyme digestion and Sanger sequencing) to generate data for analysis and interpretation (Day 3). You will also directly test your phenotype using PTC taste paper (Day 3). The genotypic data from the class will then be used to perform Hardy-Weinberg Principle analysis to determine if the genetic variation within the class meets expected allelic ratios. (See the Experimental Flow Chart on the following page). Laboratory Safety: These labs require students to work with proteinase K, ethidium bromide and UV light. Care should also be taken, using sterile techniques, to avoid contamination of the samples. Use of gels significantly reduces the exposure to ethidium bromide. The E-gel waste (ethidium bromide) should be disposed of properly. Cell waste should be disposed of properly. Students should wear lab coats, gloves, and eye protection during these experiments. UV protective shields must be in place when visualizing with a UV transilluminator. Concern about the safety of the PTC tasting strips has been questioned by Texley 2004, et al., however further evaluation by Merrit 2008 compares the toxicity of PTC to common table et al., salt and they state calculate that the 230 mg of NaCl (salt) in a vending machine bag of “We potato chips is about 100 times more toxic than the .007 mg of PTC in a taste paper.” There has been 75 years of PTC research without any evidence of toxicity associated with PTC taste paper (Merritt 2008; Wooding, 2006). et al.,
maintain taster and non-taster alleles in humans conferring an advantage to heterozygotes perhaps by increasing the repertoire of bitter toxins that can be detected through the diverse receptors (Wooding et al., 2004). Experimental Overview Your ability to taste thiourea-containing compounds will be evaluated by examining both your phenotype and genotype. First, using your self-knowledge of the foods you like and dislike, you will form a testable hypothesis (Taster or Non-taster). Once you have your hypothesis you will determine your genotype by; isolating your genomic DNA (Day 1), PCR amplifying the genetic area of interest using the dCAPs method (Day 2), and using two different methods (restriction enzyme digestion and Sanger sequencing) to generate data for analysis and interpretation (Day 3). You will also directly test your phenotype using PTC taste paper (Day 3). The genotypic data from the class will then be used to perform Hardy-Weinberg Principle analysis to determine if the genetic variation within the class meets expected allelic ratios. (See the Experimental Flow Chart on the following page). Laboratory Safety: These labs require students to work with proteinase K, ethidium bromide and UV light. Care should also be taken, using sterile techniques, to avoid contamination of the samples. Use of significantly reduces the exposure to ethidium bromide. The E-gel waste (ethidium bromide) should be disposed of properly. Cell waste should be disposed of properly. Students should wear lab coats, gloves, and eye protection during these experiments. UV protective shields must be in place when visualizing gels with a UV transilluminator. Concern about the safety of the PTC tasting strips has been questioned by Texley et al., 2004, however further evaluation by Merrit et al., 2008 compares the toxicity of PTC to common table salt and they state “We calculate that the 230 mg of NaCl (salt) in a vending machine bag of potato chips is about 100 times more toxic than the .007 mg of PTC in a taste paper.” There has been 75 years of PTC research without any evidence of toxicity associated with PTC taste paper (Merritt et al., 2008; Wooding, 2006).
Murray%20et%20al%202016_Student%20Manual%20PTC.docx