alleles

• • Different forms of the same gene are found at the same location on a pair of homologous chromosomes
• • The sequence of DNA bases is slightly different between alleles for a particular gene
• • Homozygous: 2 alleles for a specific gene are the same because DNA sequences are identical
• • Heterozygous: 2 alleles of a specific gene are different because DNA sequences vary slightly
• • Dominant allele always expressed when present in genotype
• • Recessive allele only expressed in the absence of dominant allele in the genotype