Dominant and Recessive Alleles:
Out of the two alleles of a gene, the allele which masks any phenotypic effect of any recessive allele is called dominant allele. While the allele that is masked is called recessive allele. For example, the allele controlling the rolling of tongue is dominant allele and the allele which controls the condition in which tongue cannot be rolled is recessive allele.
Genotype and Phenotype:
The genetic constitution of an organism in which the genes are present in various combinations is called genotype. On the other hand, the externally visible expression of genes, which is an inherited feature in an individual’s appearance, is called phenotype. For every phenotype, there may be two conditions, homozygous and heterozygous. Homozygous condition: A condition in which a pair of a homologous chromosomes carries identical alleles on a gene locus for a specific trait.
Heterozygous condition: A condition in which a pair of homologous chromosomes carries non- identical alleles on a gene for a specific trait.