Understanding PTC Taste Sensitivity

Introduction

• PTC stands for a chemical used in genetic classes.
• PTC paper: used to test taste sensitivity, with varied reactions.
  • Some taste bitterness.
  • Some taste nothing.

Genetics of PTC Taste Sensitivity

• The ability to taste PTC is genetically determined.
• Genes and DNA:
  • Genes are DNA portions coding for traits.
  • Traits can be influenced by multiple genes.

Chromosomes and Alleles

• Humans have 46 chromosomes (23 pairs).
• Inherited 23 from each parent.
• Chromosomes contain genes that determine traits.
• Alleles:
  • Variants of genes.
  • Determine traits like PTC sensitivity.

Genotypes and Phenotypes

• Genotypes determine Phenotypes (physical traits).
• Alleles are represented by letters (T).
  • "T" for dominant allele.
  • "t" for recessive allele.
• Possible genotype combinations: TT, Tt, tt.
  • PTC Taster: TT or Tt (dominant alleles present).
  • Non-Taster: tt (only recessive alleles).

Inheritance Patterns

• Dominance: One dominant allele results in trait expression.
• Example Scenario:
  • Both parents taste PTC (Tt genotype).
  • Offspring (tt genotype) cannot taste PTC.

Misconceptions About Dominance

• Dominant traits are not always more common.
  • Dominant allele may be rare (e.g., polydactyly).

Conclusion

• PTC taste sensitivity is a powerful example in genetics education.
• Dominance in traits does not imply prevalence.
• Stay curious about genetics and inheritance.

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