Extension of mendelian inheritance
Extension of mendelian inheritance
Incomplete Dominance
Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes. Incomplete dominance is similar to, but different from co-dominance. In co-dominance, an additional phenotype is produced , however both alleles are expressed completely. Co-dominance is exemplified in AB blood type inheritance. Incomplete dominance is seen in cross-pollination experiments between red and white snapdragon plants. The dominant allele that produces the red color is not completely expressed over the recessive allele that produces the white color. The resulting offspring are pink
Co-Dominance
Co-dominance is similar to incomplete dominance in that there is no dominant allele. However, the phenotypic expression is quite different. If two alleles have a co-dominance relationships, in the heterozygote both alleles will be completely expressed. For example, in human ABO blood types, two of the three alleles (the A allele, properly designated as IA, and the B allele, properly designated as IB) are co-dominant. This gene controls the deposition of antigenic markers on cells. A person with blood type A (homozygous for IA or heterozygous for IA and the recessive i (for O type)) has one kind of antigen marker, while a person with blood type B (homozygous for IB or heterozygous for IB and the recessive i (for O type)) has a slightly different kind of antigen marker. The heterozygote has blood type AB, and this person's cells have both A antigens and B antigens on their surfaces. There is no "in-between" antigen, as would be expected if the alleles showed
incomplete dominance. Both of the alleles are completely expressed, and the person has both blood types at the same time.
Sex-limited traits
Sex-limited genes are genes that
Incomplete Dominance
Incomplete dominance is a form of intermediate inheritance in which one allele for a specific trait is not completely dominant over the other allele. This results in a third phenotype in which the expressed physical trait is a combination of the dominant and recessive phenotypes. Incomplete dominance is similar to, but different from co-dominance. In co-dominance, an additional phenotype is produced , however both alleles are expressed completely. Co-dominance is exemplified in AB blood type inheritance. Incomplete dominance is seen in cross-pollination experiments between red and white snapdragon plants. The dominant allele that produces the red color is not completely expressed over the recessive allele that produces the white color. The resulting offspring are pink
Co-Dominance
Co-dominance is similar to incomplete dominance in that there is no dominant allele. However, the phenotypic expression is quite different. If two alleles have a co-dominance relationships, in the heterozygote both alleles will be completely expressed. For example, in human ABO blood types, two of the three alleles (the A allele, properly designated as IA, and the B allele, properly designated as IB) are co-dominant. This gene controls the deposition of antigenic markers on cells. A person with blood type A (homozygous for IA or heterozygous for IA and the recessive i (for O type)) has one kind of antigen marker, while a person with blood type B (homozygous for IB or heterozygous for IB and the recessive i (for O type)) has a slightly different kind of antigen marker. The heterozygote has blood type AB, and this person's cells have both A antigens and B antigens on their surfaces. There is no "in-between" antigen, as would be expected if the alleles showed
incomplete dominance. Both of the alleles are completely expressed, and the person has both blood types at the same time.
Sex-limited traits
Sex-limited genes are genes that