CODOMINANCE

• WHAT IS CODOMINANCE?

  when both alleles are expressed in the phenotype
• WHAT ARE MULTIPLE ALLELES?

  more than two alleles of which only two are present on the loci of an individual's homologous chromosomes
• EXAMPLE OF CODOMINANCE?

  coat colour in cattle

  -> CRCR: red coat

  -> CWCW: white coat

  -> CRCW/ CWCR: roan coat

  code for an enzyme catalysing the formation of red pigment in cattle hairs (or an altered enzyme without this function)
• EXAMPLE OF MULTIPLE ALLELES?

  blood type

  IA and IB (codominant), IO (recessive)

  -> different alleles code for different antigens on the cell-surface membrane of red blood cells

  BLOOD TYPES

  A: IAIA/ IAIO

  B: IBIB/ IBIO

  AB: IAIB

  O: IOIO