Allele refers to 2 or more alternative forms of a gene that are found in the same place of a chromosome. Alleles can code for a range of characteristics such as hair or eye colour in humans. However, these are not Mendelian, meaning that more than one allele affects them. Freckles on the other hand is a Mendelian trait and is also the dominant trait to not having freckles. If two parents that both have one allele for freckles and one allele for not having freckles were to have children, what would be the probability that their child does not have freckles even though both parents have freckles?

To find that out we can setup a monohybrid cross. In this case, mono means that we are considering only one gene and hybrid means that both parents are heterozygotes, meaning that they have one of each gene. To setup up this monohybrid cross we draw a 2x2 table, called a Punnett square and place the alleles of one parent on top of the table and the other parent’s alleles on the left of the table.

We can then fill in the table by filling each square with one letter from each parent like so. The results will be the following, dominant, dominant, dominant recessive, dominant recessive and recessive, recessive. In other words, the probability of these parents having children with alleles FF is 25%, Ff is 50% and ff is 25%. This is also what we refer to as the resulting genotype. The resulting phenotype, i.e. how the children actually look is dependent on the fact that freckles is dominant meaning that having allele for freckles is enough for the child to have freckles. In other words, if these 2 parens were to have a child, the chance it would not have freckles would be only 25%.

Sources:

Nicole Lantz: [ Ссылка ]

Amoeba Sisters: [ Ссылка ]

Professor Dave Explains: [ Ссылка ]

[[ Ссылка ]/Genetics_Textbook/04%3A_Inheritance/4.02%3A__Mendelian_Genetics/4.2.01%3A_Monohybrid_Crosses_and_Segregation]([ Ссылка ]/Genetics_Textbook/04%3A_Inheritance/4.02%3A__Mendelian_Genetics/4.2.01%3A_Monohybrid_Crosses_and_Segregation)

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[[ Ссылка ] of red hair,-As mentioned above&text=MC1R is a recessive gene,child to be a redhead]([ Ссылка ]).

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