Vocab

• True Breeding


  Any crosses performed will result in an offspring with the same phenotype, indicating that the organism is homozygous for every gene
• Recombinant Offspring

  Offspring that have a different allele combination to their parents
• Test Cross

  • A method of determining the genotype of an organism that expresses the dominant phenotype
  • The organism is mated with a recessive phenotype
  • The phenotypes of the offspring are then analyzed
• Homozygous


  Refers to having inherited the same alleles of a genomic marker from each biological parent
• Germ Cell

  Reproductive cells that become egg or sperm
• Genotype

  The combination of alleles that an individual possesses for a specific gene
• Dominant


  Version of a gene that expresses itself and masks the other gene
• Phenotype

  Set of observable characteristics of an individual resulting from the interaction of its genotype with the environment
• Non-Disjuction


  The failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during meiosis, usually resulting in an abnormal distribution of chromosomes in the daughter nuclei
• Sex Chromosomes


  Are chromosomes that carry the genes that determine the sex of an individual
• Autosomes


  One autosome is one of the numbered chromosomes
• Karyotype

  An individuals complete set of chromosomes
• Interkinesis

  Period of rest that cells enter during meiosis before entering meiosis two
• Independent Assortment

  • How different genes independently separate from one another in meiosis
  • Sorted into gametes independently of one another
  • Alignment of chromosomes at the metaphase plate is random
  • Separate alleles for separate traits are passed on independently of each other
• Recombination

  Exchange of genetic material between multiple chromosomes or different regions of the chromosome
• Synaptonemal Complex


  Is a proteins structure that forms between homologous chromosomes
• Recessive

  Refers to a trait that is expressed only when genotype is homozygous: a trait that tends to be masked
• Crossing Over

  Refers to the exchange of DNA between paired homologous chromosomes
• Tetrads

  A pair of chromosomes, four chromatids
• Chiasma

  The point of contact, physical link between two chromatids belonging to homologous chromosomes
• Synapsis

  The fusion of chromosome pairs at the start of meiosis
• Homologous Pairs

  Paired chromosomes that have different alleles, one maternal and paternal chromosomes pair up
• Diploid Chromosomes

  A cell containing two copies of each chromosome
• Sister Chromatids

  Refers to the identical copies formed by the DNA replication of a chromosome with both copies join together by centromere
• Gametes

  An organisms reproductive cells
• Somatic Cell

  Any biological cell forming the body of a multicellular organism other than a gamete, germ cell and gametocyte site
• Laws of Segregation

  • Alleles segregate randomly into gametes
  • When gametes form each allele of one parent segregates randomly into the gametes
  • One allele will be present in each gamete
  • Segregation of occurs during anaphase
• Heterozygous

  Having two different alleles of a particular gene