co dominance ,incomplete dominance and complete dominance |urdu| hindi| скачать в хорошем качестве

co dominance ,incomplete dominance and complete dominance |urdu| hindi|

mendel's law of independent assortment.    • Mendel's law of independent assortment | d...   ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: role of gene in protein synthesis.    • Role of gene in protein synthesis. class 1...   ::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::::: Co-dominance is the situation where two different alleles of a gene pair express themselves completely, instead of showing a dominant-recessive relationship. As a result, the heterozygous organism shows a phenotype that is different from both homozygous parents. An example of co-dominance is the expression of human blood group AB. The ABO blood group system is controlled by the gene ‘I’. This gene has three alleles i.e. IA, IB and i. The allele IA produces antigen A in blood and the phenotype is blood group A. The allele IB produces antigen B in blood and the phenotype is blood group B. The allele i does not produce any antigen and the phenotype is blood group O. The alleles IA and IB are dominant over i. When there is a heterozygous genotype of IA IB, each of the two alleles produces the respective antigen and neither of them dominates over the other. In-complete dominance is the situation where, in heterozygous genotypes, both the alleles express as a blend (mixture) and neither allele is dominant over the other. As a result of this blending, an intermediate phenotype is expressed. Following is the familiar example of incomplete dominance. In Four ‘O’ clock plant, the trait of flower colour is controlled by two alleles (let us say them R and r). The true breeding plants RR and rr have red and white flowers, respectively. When a homozygous red flowered plant (RR) is crossed with homozygous white flowered plant (rr), the heterozygous (Rr) plants of F1 generation produce pink flowers (pink is a blend of red and white colours). This result clearly indicates that neither of the red flower allele (R) and white flower allele (r) is dominant. However, when two heterozygous plants with pink flowers (Rr) are crossed, F2 generation shows phenotypes of red, pink and white flowers in the ratio 1:2:1. #codominance #incompletedominance