monohibrid

A monohybrid cross is a breeding experiment between two organisms that are identically hybrid for one gene. This means that both parents are heterozygous for a single trait, carrying one dominant and one recessive allele for that gene. For example, if we consider a gene for flower color where 'P' represents the dominant allele for purple flowers and 'p' represents the recessive allele for white flowers, a monohybrid cross would involve crossing two plants with the genotype Pp.

The purpose of a monohybrid cross is to observe the inheritance patterns of a single gene and to determine the relationship between dominant and recessive alleles. When two heterozygotes (Pp x Pp) are crossed, the offspring genotypes can be predicted using a Punnett square. The possible genotypes are PP, Pp, and pp in a ratio of 1:2:1. This means that one-quarter of the offspring will be homozygous dominant (PP), half will be heterozygous (Pp), and one-quarter will be homozygous recessive (pp).

In terms of phenotypes, if the dominant allele completely masks the recessive allele (complete dominance), the phenotypic ratio observed in the offspring of a monohybrid cross is typically 3:1. Three-quarters of the offspring will display the dominant phenotype (purple flowers in our example), and one-quarter will display the recessive phenotype (white flowers). This observation was fundamental to Gregor Mendel's laws of inheritance, specifically his law of segregation, which states that the alleles for each gene segregate from each other during gamete formation. Monohybrid crosses are a foundational concept in genetics for understanding basic inheritance.