Lecture on PTC Taste Sensitivity and Genetics

Introduction to PTC

• PTC (Phenylthiocarbamide): A chemical used in genetic classes due to its taste sensitivity trait.
• PTC Paper: Used to test PTC sensitivity; some taste it as bitter, others taste nothing.
• Genetic Trait: The ability to taste PTC is dictated by genetics.

Genetics Overview

• Genes: Portions of DNA coding for characteristics, such as taste sensitivity.
• Chromosomes: 46 in humans, 23 from each parent.
• Alleles: Variants of a gene; each parent contributes one allele.

PTC Taste Sensitivity

• Gene Locus: Specific area on chromosomes where the PTC taste gene is located.
• Alleles and Genotypes:
  • Allele Representation: Capital letter (dominant) or lowercase (recessive).
  • Genotypes: TT, Tt, or tt.
  • Phenotype: Physical characteristic determined by genotypes.
  • Dominant Trait: Ability to taste PTC (at least one dominant allele - T).
  • Recessive Trait: Cannot taste PTC (tt genotype).

Genetic Examples and Probabilities

• Parental Genotypes: If both parents are Tt (tasters), offspring can be tt (non-taster).
• Punnett Squares: Predicts offspring genotypes and phenotypes (topic for future video).

Dominance and Commonality

• Dominant Traits: Not always more common; depends on allele frequency in population.
• Example: Polydactyly (extra fingers) can be dominant but rare in population.

Conclusion

• Stay Curious: Continuous learning and curiosity are encouraged.