Gentic inheritance

• PTC


  A chemical that can be sold on paper strips and used in genetic classes
• Some people can taste PTC, some people cannot taste PTC
• The ability to taste PTC or not is based on genetics
• Genes


  Portions of DNA that code for characteristics or traits
• Many traits are coded for by interactions of more than one gene
• The ability to taste PTC or not may involve some other gene interactions
• There are different ranges for how bitter the PTC chemical may taste due to more kinds of alleles
• The ability to taste PTC or not taste PTC is at least heavily impacted by a specific gene
• The author's parents can both taste PTC, but the author cannot
• Chromosomes


  Condensed units of DNA and protein that represent a person's whole genetic code
• Humans have 46 chromosomes, inheriting 23 from each parent
• Allele


  A variant or form of a gene
• Dominant allele


  An allele that is expressed when present, even if only one copy is inherited
• Recessive allele


  An allele that is only expressed when two copies are inherited, with no dominant allele present
• Genotype


  A person's genetic makeup, the combination of alleles they have inherited
• Phenotype


  A person's physical characteristic or trait
• Being able to taste PTC is a dominant trait
• The genotypes that can taste PTC are TT and Tt
• The genotype that cannot taste PTC is tt
• The author's parents have the Tt genotype, making them PTC tasters
• Punnett squares can be used to determine probabilities of offspring genotypes and phenotypes
• The dominant trait of being able to taste PTC is more common than the recessive trait of not being able to taste PTC
• Dominant traits are not always more common in a population, as the dominant allele itself may be rare