Inheritance

• Gene

  short section of DNA that determines a specific characteristic
• Allele

  An alternative form of gene occupying a similar loci on the homologous chromosome
• Dominant alleles

  Always expressed when present
• Recessive allele

  only expressed when the dominant isn't present
• Genotype

  A combination of alleles present
• Phenotype

  The characteristic of an organism
• Codominance

  When both alleles contribute to the phenotype
• Mendel's first law

  The characteristic of an organism are determined by factors which occur in pairs. Only one member of factors can be represented in a single gamete.
• Monohybrid inheritance

  The inheritance of a single pair of contrasting characters
• Homozygous

  2 alleles that are the same
• Heterozygous

  2 alleles that are different
• Test cross

  Method used to determine whether an organism with a dominant characteristic is homozygous or heterozygous for that gene
• test cross

  • Unknown dominant genotype is crossed with a recessive genotype
  • If the unknown is heterozygous you should expect a 1:1 ratio of homozygous and heterozygous
  • If unknown is homozygous then you should expect all the offspring to be heterozygous dominant
• Chi squared test

  It is a way of estimating the probability that the difference between observed and expected results are really due to chance
• How to form a null hypothesis

  1. There is no significant difference between...
  2. Any difference is due to chance
• Incomplete dominance

  • Both alleles are expressed equally and neither seems to dominate, resulting in a mixture of both alleles.
  • Alleles are described as partially dominant
• sex linkage

  Refers to any gene on the X chromosome not found on the Y chromosome
• Females are XX
• Males are XY
• Mutations

  A change in the amount, arrangement or structure in the hereditary material of an organism
• Mutations are random and spontaneous