Question

In humans premature gray hair is dominant over normal hair color. Cross a homozygous premature gray haired person to a homozygous normal haired person.​

Answer 1

The children of homozygous dominant parents will develop premature grey hair and the progeny will have typical hair colouring if they are heterozygous will be obtained.

• In addition to age, other variables can affect when a person's hair begins to change colour.
• The first is genetics; if your parents began ageing early, there is a possibility that you will as well.
• A factor is also ethnicity.
• According to research, Caucasians experience greying sooner than African Americans.
• The IRF4 gene, which has one particular variant (rs12203592) that is a marker for early greying, affects when a person's hair starts to turn grey.
• Another gene called TYR, which produces an enzyme required for the production of melanin, is controlled by the IFR4 gene.
• Genetics plays a major role in how hair ages, transitioning from a deeper colour to white or grey.
• Either of your parents may pass it down to you.
• Our unique hair pigment type determines the colour of our hair.

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Answer 2

According to, some of the steps are:

• Identify the alleles of each parent for the trait of interest. Use capital letters for dominant alleles and lowercase letters for recessive alleles. For example, if premature gray hair is dominant over normal hair color, use G for gray hair and g for normal hair.
• Write the possible gametes of each parent along the top and left sides of a square. Each gamete will have one allele for the trait. For example, if a parent is homozygous for gray hair (GG), the gametes will be G and G. If a parent is homozygous for normal hair (gg), the gametes will be g and g.
• Fill in the boxes of the square by combining the gametes from each parent. Each box will have two alleles that represent the genotype of an offspring. For example, if a gamete with G meets a gamete with g, the box will have Gg.
• Count the number and ratio of each genotype and phenotype among the offspring. For example, if all the boxes have Gg, then all the offspring will have a heterozygous genotype and a gray-haired phenotype.

Using these steps, we can cross a homozygous premature gray haired person (GG) with a homozygous normal haired person (gg) and create a Punnett square as follows:

       G G

g Gg Gg

g Gg Gg

Conclusion

The Punnett square shows that all the offspring will have a heterozygous genotype (Gg) and a gray-haired phenotype. The genotypic ratio is 4:0 for Gg:gg and the phenotypic ratio is 4:0 for gray hair:normal hair.

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