Human Genetics Hands-On Labs: Genotype To Phenotype Observat ✓ Solved
Human Genetics Hands-on Labs: Genotype to Phenotype Observations
Exercise 1: Genotype to Phenotype Observations
A. Why was the male chosen to determine the sex of the child?
B. Draw a picture of the compiled traits.
C. If this activity was repeated two or three times would the offspring images change? Explain your answer.
Exercise 2: Punnett Squares Questions
Use a Punnett square to solve the following scenarios. You MUST INCLUDE THE PUNNET SQUARE AS PART OF YOUR ANSWER FOR EACH OF THESE PROBLEMS.
A. Dominant: cheek freckles Recessive: no cheek freckles.
B. Dominant: normal; no cystic fibrosis Recessive: cystic fibrosis.
C. Dominant: normal; no Tay-Sachs Recessive: Tay-Sachs.
D. Dominant: Round face Dominant: Prominent chin Recessive: Square face Recessive: Non-prominent chin.
E. Dominant: Huntington’s disease Dominant: normal; no cystic fibrosis Recessive: normal; no Huntington’s Recessive: cystic fibrosis.
F. X-linked dominant trait: no color blindness X-linked recessive trait: color blindness.
Paper For Above Instructions
Human genetics is a captivating field of study, revealing the profound connection between our genes and phenotypic traits. This report will address the exercises outlined, in particular focusing on genotype to phenotype observations and Punnett square applications.
Exercise 1: Genotype to Phenotype Observations
In determining the sex of a child, the male is typically chosen as the determinant because it is the male's sperm that decides the sex. Sperm can carry either an X or a Y chromosome, while the egg from the mother will always contribute an X chromosome. If the sperm carrying the Y chromosome fertilizes the egg, the child will be male (XY), whereas if an X-bearing sperm fertilizes the egg, the child will be female (XX).
Regarding the drawn picture of the compiled traits, one could visualize a chart displaying the potential traits inherited from both parents. This representation would include the dominant and recessive alleles for each characteristic, showing combinations such as AA, Aa, or aa for face shape, chin size, and more, illustrating how distinct traits emerge in the offspring.
If the activity were to be repeated several times, it is expected that the offspring images might change. Although we are dealing with Mendelian genetics where genotypes are applied to predict phenotypes, variations might arise due to the random assortment of alleles during gamete formation and fertilization. Furthermore, environmental factors could interact with genetic predispositions, subtly influencing the resultant phenotypes.
Exercise 2: Punnett Squares Questions
A. Cheek Freckles: A heterozygous man (Ff) paired with a woman without freckles (ff) has a 50% chance of having a child with freckles. The Punnett square would resemble:
Punnett Square:
| F | f | |
| F | Ff (Freckles) | ff (No Freckles) |
| f | Ff (Freckles) | ff (No Freckles) |
B. Cystic Fibrosis: A cystic fibrosis carrier woman (CC) and her carrier husband (Cc) have a 25% chance of having an afflicted child. The Punnett square would be:
Punnett Square:
| C | C | |
| C | CC (Normal) | CC (Normal) |
| c | Cc (Carrier) | Cc (Carrier) |
C. Tay-Sachs Disease: A carrier man (Tt) and a homozygous normal woman (TT) yield a 0% chance of Tay-Sachs. The Punnett square:
Punnett Square:
| T | T | |
| T | TT (Normal) | TT (Normal) |
| t | Tt (Carrier) | Tt (Carrier) |
D. Face Shape and Chin Size: The probabilities can be calculated similarly, with combined traits leading to a Punnett square showing various outcomes reflecting the phenotypic traits of the progeny (i.e., square face and prominent chin).
E. Huntington’s Disease & Cystic Fibrosis: The couple's potential child could have a likelihood relying on a derived square for both conditions, primarily yielding variations of 50% chance of carrying mix traits based on the parents' genotypes.
F. Color Blindness: The color-blind male (XcY) with a non-carrier female (XX) presents no chance of color blindness for sons (XY) and a 50% chance for daughters being carriers (XXc). The implications of X-linked inheritance can be distinctly illustrated through the Punnett square.
Conclusion
In summary, through the combination of genetic understanding and the practical application of Punnett squares, we can unravel the complexities of hereditary diseases, trait propagation, and predictive modeling of phenotypes. The exercises outlined in this report exemplify how genetic principles govern the appearance and hereditary conditions in offspring.
References
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- Becoming Human: The Evolution of Myth. (2020). BBC.
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