Genetics

• genotype: the genetic constitution of an organism (the alleles it has for a gene)
• phenotype: the expression of the genes and its interaction with the environment
• homozygous: a pair of homologous chromosomes carrying the same alleles for a single gene
• heterozygous: a pair of homologous chromosomes carrying two different alleles for a single gene
• recessive allele: an allele only expressed if no dominant allele is present
• dominant allele: an allele that will always be expressed in the phenotype
• codominant: both alleles are equally dominant and expressed in the phenotype
• multiple alleles: more than two alleles for a single gene
• sex-linkage: a gene whose locus is on the X chromosome
• autosomal linkage: genes that are located in the same chromosome (not the sex chromosome)
• epistasis: when one gene modifies or masks the expression of a different gene at a different locus
• monohybrid: genetic inheritance cross of a characteristic determined by one gene
• dihybrid: genetic inheritance cross for a characteristic determined by two genes
• why is chi squared used?

  categorical data
• why are statistical tests applied to data about offspring ratios?

  to determine the probability of the results being due to chance
• assumptions of hardy weinberg:

  • organisms are diploid
  • reproduce by sexual reproduction only
  • no overlap between generations
  • mating is random
  • the population is large
  • no migration, mutation or selection
  • allele frequencies are equal in both sexes