Describe dominant–recessive inheritance. Provide at least three examples each of dominant and recessive characteristics

Question

What will be an ideal response?

Answer 1

Except for the XY pair in males, all chromosomes come in matching pairs. Two forms of each gene occur at the same place on the chromosomes, one inherited from the mother and one from the father. Each form of a gene is called an allele. If the alleles from both parents are alike, the child is homozygous and will display the inherited trait. If the alleles differ, then the child is heterozygous, and relationships between the alleles determine the phenotype. In many heterozygous pairings, dominant–recessive inheritance occurs: Only one allele affects the child's characteristics. It is called dominant; the second allele, which has no effect, is called recessive. Using hair color as an example: The allele for dark hair is dominant (we can represent it with a capital D), whereas the one for blond hair is recessive (symbolized by a lowercase b). A child who inherits a homozygous pair of dominant alleles (DD) and a child who inherits a heterozygous pair (Db) will both be dark-haired, even though their genotypes differ. Blond hair can result only from having two recessive alleles (bb). Still, heterozygous individuals with just one recessive allele (Db) can pass that trait to their children. Therefore, they are called carriers of the trait. Some dominant characteristics are: dark hair, curly hair, facial dimples, farsightedness, and double-jointedness. Some recessive characteristics are: straight hair, red hair, nearsightedness, blond hair, and type O blood.