lecture 18 - mendelian inheritance

• What is the relationship between genotype and phenotype?


  Genotype determines the phenotype of an organism.
• How can knowledge of genetics be used in predicting offspring traits?


  It allows us to calculate the likelihood of specific genotypes and phenotypes in offspring.
• What does the notation 2n=16 indicate about a species?


  The species is diploid with 16 chromosomes per cell.
• What is the definition of genotype?


  Genotype is the genetic constitution of an organism.
• What is the definition of phenotype?


  Phenotype is the observable characteristics resulting from the interaction of genotype and environment.
• What are alleles?


  Alleles are alternative versions of a single gene.
• What does it mean to be homozygous?

  Homozygous means having the same alleles of a gene.
• What does it mean to be heterozygous?


  Heterozygous means having different alleles of a gene.
• What is a dominant allele?


  A single allele is sufficient for full phenotypic expression.
• What is a recessive allele?


  A recessive allele requires two copies for full phenotypic expression.
• What are the two laws of inheritance proposed by Gregor Mendel?

  1. Law of Segregation
  2. Law of Independent Assortment
• What does the Law of Segregation state?

  • The two alleles for each trait separate during gamete formation.
  • Gametes unite at random during fertilization.
• How can you distinguish genotype from phenotype?


  --> by performing a test cross
• What is a testcross used for?

  A testcross is used to determine the unknown genotype of an organism with a dominant phenotype. To perform, cross to homozygous recessive partner.
• What does the Law of Independent Assortment state?

  • Alleles of different genes assort independently of one another during gamete formation.
  • Dihybrid crosses reveal this law.
• How do Mendel's results rule out the linked assortment hypothesis?

  The presence of offspring with non-parental phenotypes indicates independent assortment.
• Pure/True Breeding


  Any cross performed will result in offspring with the same phenotype