INCOMPLETE & CODOMINANCE

=Incomplete Dominance= Sometimes there are two different versions of a gene and neither is dominant over the other. A common example of this is found in snapdragons (a type of flower). There are two versions of a gene for flower colour, one codes for Red flowers, the other White flowers. When a plant inherits one copy of each (is heterozygous) the colours mix and the resulting flowers are pink (see below, note the resulting phenotype ratio). This ‘mixing’ of characteristics is known as incomplete dominance. Because neither allele is dominant over the other we can’t simply use upper and lower case letters. Instead we represent the alleles as follows: [image:http://i.imgur.com/xcB8CLa.png?2] =Co-Dominance= In some flower varieties we find it is possible for two different versions of a gene (alleles) that code for different characteristics to both be expressed independently. You can think of both alleles as being dominant. Here the characteristics '''do not mix'''; rather heterozygotes will display both characteristics. Using flowers as an example, heterozygotes display both red and white patches. Again the alleles are written as follows: [image:http://i.imgur.com/YuAqg9E.png?1]