Chapter 14

  1. character
    a heritable feature that varies among individuals
  2. trait
    each variant for a character (ex: purple or white flowers)
  3. hybridization
    the mating/crossing of two true-breeding varieties (Crossing a plant with purple flowers with a plant with white flowers)
  4. allele
    alternative versions of genes (in pea plants, purple flowers on a plant or white flowers)
  5. the law of segregation
    two alleles for a heritable character segregate during gamete formation and end up in different gametes; aka an egg or sperm gets only one of the two alleles that are present in the somatic cells of the organism making the gamete
  6. testcross
    breeding an organism with an unknown genotype with a recessive homozygote; will reveal the genotype of said organism
  7. monohybrid
    when a progeny is all heterozygous for one character
  8. dihybrid
    individuals heterozygous for two characters
  9. law of independent assortment
    each pair of alleles segregates independently of each other pair of alleles during gamete formation; applies mostly to alleles controlled by genes on different chromosomes
  10. complete dominance
    the phenotypes of heterozygotes and dominant homozygotes are undistiguishable
  11. incomplete dominance
    when neither allele is comepletely dominant and F1 hybrids have a phenotype somewhere in the middle of the two parental varieties; ex: red/white snapdragons, roan coloring in cows; heterozygotes have an intermediate phenotype
  12. codominance
    two alleles affect the phenotype in seperate ways; aka different phenotypes expreseed together; ex: blood type, and MN molecules in blood
  13. pleiotropy
    when a single gene influences most genes have multiple phenotypic traits
  14. epistasis
    a gene at one locus alters the phenotypic expression of a gene at a second locus
  15. quantitative characters
    when an either-or classification is impossible because the characters vary in the population along a continuum (in gradiations)
  16. polygenic inheritance
    the additive effect of alleles at multiple loci, or two or more genes on a single phenotypic character (opposite of pleiotropy)
  17. norm of reaction
    describes the pattern of phenotypic expression of a single genotype across a range of environments; ex: has no effect on blood type, but a person's count of red/white blood cells can vary; broadest for polygenic characters
  18. multifactorial
    many factors, both genetic and environmental, collectively influence people
  19. aminocentesis
    tests can determine, by extracting amniotic fluid and examining the cells found, whether the developing fetus will have a disease or not
  20. chorionic villus sampling
    CVS; a physician inserts a tube through the cervix into the uterus and removes a sample of tissue from the placenta; the cells removed have the same genotype as the fetus
Card Set
Chapter 14
midterm 3