University:
Western Sydney University
Course:
MEDI 2003 | Clinical Sciences 2
Academic year:

2024
Views:

365

Pages:

3
Author:

Mariam A. A.

Co-dominance Inheritance ✓ Co-dominance refers to the genetic expression of both alleles in which the result is the combined impact of both alleles. ✓ An example of co-dominance is when a cow has both red and white colour patches on its skin. These cows are known as roan cows. Roan cows come from the crossing over (mating) of red and white parent cows. ✓ The offspring that have exhibit co-dominance must be heterozygous! They have different alleles for the same gene. Let’s suppose you have a homozygous red female cow (RR) and a homozygous white male cow (WW). If these two cows are crossed, the cow offspring will 100% be roan (RW) as shown in the diagram below. Incomplete Dominance Inheritance ✓ A heterozygous genotype that results in a blend of the alleles in the phenotype. ✓ If we do the Punnett square crossing, we will find that resulting snapdragon offspring will have a 100% chance to have the genotype combination, RW. This genotype (RW) will give the phenotype of pink-coloured snapdragons. The red allele is not capable of coding sufficient red pigment for the snapdragon flowers to have a complete red colour. Vice versa, the white allele is not capable for coding sufficient white pigment for the snapdragon flower to have a complete white colour. What is the phenotype and genotype of the possible offspring of homologous pink flower and a heterozygous purple flower? • • • • If both are the same colour or the same characteristic that means that for homo both are caps and for hetero one big and one small. For example, for homo we have a pink flower and for hetero we also have a pink flower, but the hetero is recessive for white, that means for homo we have PP and for hetero we have Pp, where P is for pink and p is for white. But if they have a different colour or trait, that means for homo it only has the recessive trait so both are small case. However, for hetero one big and on small. For the highlighted example, pp and for hetero Pb Phenotype is described using words. Genotype is described using symbols.