epistasis

• What is the definition of epistasis?

  One gene influences the expression of another
• What color are labradors controlled by epistasis?

  Black, brown, and yellow
• What does gene one control in labradors?

  Whether pigment is produced in fur
• What does the dominant allele E code for in labradors?

  Pigment production
• What color will a labrador with two recessive e alleles be?

  Yellow or golden
• What does gene two control in labradors?

  Which pigment is expressed for color
• What does the dominant allele B code for in labradors?

  Black fur
• What does the recessive allele b code for in labradors?

  Brown fur
• What is the genetic cross for two heterozygous labradors?

  • Both parents are heterozygous for both genes
  • Possible gametes: E, e, B, b
  • Punnett square shows combinations
  • Results in phenotypes: black, brown, yellow
• What phenotype results from two recessive e alleles in labradors?

  Yellow, regardless of second gene
• What is the phenotypic ratio from the labrador genetic cross?

  9:4:3
• How do pedigree diagrams represent inheritance?

  • Family tree format
  • Circles represent females
  • Squares represent males
  • Colors indicate fur color
• How do you determine the genotype of a brown individual in a pedigree?

  Must have two recessive b alleles
• What must a black female labrador have at least one of?

  Dominant E and dominant B alleles
• What does a dominant allele for gene one in squash indicate?

  Inhibits enzyme for color production
• What color will squash be with two recessive alleles for gene one?

  Green or yellow
• What does the dominant allele for gene two in squash produce?

  Yellow color in squash
• What phenotype results from a dominant allele for gene one and two recessive alleles for gene two in squash?

  Yellow squash
• How does the flow diagram help in determining squash color?

  Shows relationships between genotypes and phenotypes
• What is the phenotype for a squash with a dominant allele for gene one?

  White, regardless of gene two
• What is the phenotype for a squash with two recessive alleles for gene one?

  Green or yellow, depending on gene two
• What is the phenotype for a squash with two dominant alleles for gene two?

  Yellow squash
• What is the phenotype for a squash with two recessive alleles for gene two?

  Green squash
• What are the key concepts of epistasis in genetics?

  • One gene can mask another's expression
  • Involves interactions between two genes
  • Results in specific phenotypic ratios
  • Can be illustrated through pedigree diagrams