Genotypes and Phenotypes

• Heterozygous


  A genotype in a gene consisting of two different alleles
• Homozygous


  A genotype in a gene consisting of the same alleles
• Genotype


  The genetic makeup of an allele
• Phenotype


  The physical expression of the genotype
• Homozygous Dominant


  Both alleles for a gene are the same dominant allele
• Homozygous Recessive


  Both alleles for a gene are the same recessive allele
• Autosome


  The first 22 pairs in a human karyotype, autosomal chromosomes that are not sex-linked, also known as the homologous chromosomes
• Allosome


  The 23rd pair in a human karyotype, sex-linked chromosomes
• Karyotype


  An image of chromosomes from a cell arranged from largest to smallest
• What Karyotypes Tell You

  1. Species
  2. Gender
  3. Any genetic abnormalities
• Genotype + Environment -> Phenotype
• Carrier


  An organism that is heterzygous for a recessive trait, not being affected but can pass down to offspring.
• Test Cross


  Used to determine the genotype of an individual with an unknown genotype by crossing to to an individual with a homozygous recessive genotype.
• Monohybrid Cross


  A cross in which alleles of only one gene are involved
• Dihybrid Cross


  A cross in which alleles of two different genes are involved.
• Genes on non-homologous chromosomes are said to be unlinked.
• The genes that are located on one chromosome form a linkage group
• Linked Genes


  Genes whose loci are located on the same chromosome, usually close together.
• Hemizygous


  The genotype with respect to any gene carried on either the X or the Y chromosome, which comprises just a single allele for each gene. Only affects males