Alleles

• Dominant allele


  An allele that will show in the phenotype even if there is only one copy present
• Recessive allele


  An allele that will only show in the phenotype if two copies are present, with no dominant allele present
• Homozygous


  Having two copies of the same allele
• Heterozygous


  Having two different alleles
• Genotype


  The alleles present in an organism
• Phenotype


  The characteristics caused by an organism's alleles
• Chromosomes come in pairs, with one chromosome from each parent
• Genes are sections of DNA on chromosomes, and come in pairs
• Alleles


  Different versions of a gene
• Alleles for earwax


  • Allele for wet earwax (capital E)
  • Allele for dry earwax (lowercase e)
• Most characteristics are controlled by many genes acting together
• Height is an example of a characteristic controlled by many genes