Question

What is homozygous and heterozygous, how does this impact how an individual looks?

Answer 1

Homozygous – An individual is said to be homozygous for a particular gene when identical alleles of the gene are present on both homologous chromosomes.

Heterozygous – An individual is said to be heterozygous at a particular gene locus when it has two different alleles of the gene.

Impact on individual's looks –  A homozygous has either recessive (tt) or dominant allele pairs (TT), whereas the heterozygous has both recessive and dominant alleles (Tt). Notwithstanding the heterozygous always expresses the phenotype of dominant allele. Though, in some cases, due to co-dominance, both of the alleles express at the same time resulting in a combined phenotype of both of the alleles. Homozygous doesn't show extra vigour but the heterozygous can show hybrid vigours. Self breeding between the homozygous individuals (TT×TT or tt×tt) produce same trait over generations, whereas the self breeding between the heterozygous individuals (Tt×Tt) produces combination of different traits.

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