Punnett Square
Describe the Punnett Square and what it used to predict. What are the limitations of the Punnett Square?
Mom is a carrier for hemophilia but does not have the disease.
Dad does not have hemophilia
Using the Punnett Square, answer the following questions:
What is the probability a female offspring developing hemophilia?
What is the probability of a female offspring being a carrier for hemophilia?
What is the probability of a male offspring developing hemophilia?
What is the probability of a male offspring being a carrier developing hemophilia?
What is the probability of any offspring developing hemophilia?
Explain why only some offspring would develop the disease?
Discuss if this were about Cystic Fibrosis, how would the responses be different to the same question?
Sample Paper
Wk. 3 Discussion Post
Punnett Square, What it’s used to Predict and Its Limitations
Punnett Square is a useful tool that helps predict probabilities and variations that come from cross-breeding. This involves predicting crossing plants, animals, and even individuals with each other (Hurst, 2019). The limitations of Punnett squares as inheritance models include lack of information possible variation in small examples like individual families and lack of information on population occurrence of the parental genotypes.
Questions using Punnett square: If mom is the carrier for hemophilia but doesn’t have this disease whereas dad doesn’t have hemophilia.
Probability of a female offspring developing hemophilia
In this situation, a female offspring wouldn’t develop hemophilia.
Probability of the female offspring being a carrier for hemophilia
The likelihood of female offspring being a carrier is 1/2 or 50 percent. Using Punnet square, there will be one female that’s a carrier and other female that’s a non-carrier.
Probability of male offspring developing hemophilia
In this case, the probability of male offspring developing hemophilia is 1/2 or 50 percent. The Punnet square produces one male offspring that’s not affected and one male offspring that’s affected.
Probability of male offspring being carriers developing hemophilia
Male offspring will never be hemophilia carrier. Thus the probability is 0 percent. Hemophilia is a sex-related condition on the X chromosome (Ackerman, 2021). It’s a recessive allele on the X chromosome.
Probability of any offspring developing hemophilia
In this case, the probability of any offspring developing hemophilia is less, i.e., 25 percent.
Why only some offspring would develop the disease
Only some offspring will develop the disease since Hemophilia is a recessive allele, and in this case, the mom is a carrier and doesn’t have the condition, and the dad doesn’t have the disease (Yu, Han & Wang, 2021). The probability of one of the offspring having the disease is 25 percent.
How Responses Would Be Different Suppose the Question Was About Cystic Fibrosis
Suppose the question presented was about Cystic Fibrosis (CF); the responses would be different in terms of genes for developed offspring where the probabilities for CF would all be 0. This is because while Hemophilia is related to a recessive gene on X-chromosome and nearly exclusively affects men and boys, CF is a chronic disease of the lungs and digestive system where a defective gene and its protein product form thick and sticky mucus that hamper lungs causing severe lung infections. Moreover, CF occurs when both the genes in the pair have a mutation. I.e., an individual with CF inherits one gene from each parent (Stanford Medicine, n.d.).
References
Ackerman, L. (2021). Gender-Related Considerations. Pet-Specific Care for the Veterinary Team, 237. DOI: 10.1002/9781119540687
Hurst, L. D. (2019). A century of bias in genetics and evolution. Heredity, 123(1), 33-43. https://doi.org/10.1038/s41437-019-0194-2
Stanford Medicine. (n.d.). Genetics and CF. The Cystic Fibrosis Center at Stanford. https://med.stanford.edu/cfcenter/education/english/Genetics.html
Yu, S. H., Han, Z. Z., & Wang, M. (2021). Platelet immunology of patients with hemophilia. American Journal of Translational Research, 13(8), 9831. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8430101/
