A Plant With Red Flowers Is Crossed With A White Flowered Pl

A Plant With Red Flowers Is Crossed With A White Flowered Plant Of

A plant with red flowers is crossed with a white-flowered plant of the same species. All the seeds, when grown, produce plants with red flowers. Assuming that the flower color is controlled by a single pair of alleles, which allele is dominant and which is recessive?

How does inbreeding increase the incidence of recessive disorders in a population?

In cats, the allele (S) for short fur is dominant to the allele (s) for long fur. What is the phenotype of a cat with the genotype (Ss)?

The genetic disorder phenylketonuria (PKU) is caused by a recessive allele (n). The family tree below shows the incidence of the disease over three generations. What are the chances that Peter is the carrier of the PKU allele that resulted in his having an affected son?

In cats, the allele (S) for short fur is dominant to the allele (s) for long fur. In an (Ss) genotype, which allele is expressed in the phenotype?

When a particular gene is said to be ‘sex-linked’, on which chromosome is that gene usually present?

In cats, the allele (S) for short fur is dominant to the allele (s) for long fur. Which of the following genotypes is (i) heterozygous (ii) homozygous dominant? SS, Ss, ss

Why does an individual always have only two alleles for a given gene?

The genetic disorder phenylketonuria (PKU) is caused by a recessive allele (n). The family tree below shows the incidence of the disease over three generations. What is the genotype of Jane's husband?

In cats, the allele (S) for short fur is dominant to the allele (s) for long fur. What is the genotype of a true-breeding, long-furred cat?

The genetic disorder phenylketonuria (PKU) is caused by a recessive allele (n). The family tree below shows the incidence of the disease over three generations. What are the genotypes of the grandparents?

Paper For Above instruction

The inheritance of traits such as flower color in plants and fur length in cats exhibits fundamental principles of Mendelian genetics. Understanding the dominance and recessiveness of alleles, the impact of inbreeding on genetic disorders, and the patterns of sex-linked inheritance provides insight into genetic variation within populations. This essay explores these concepts through specific examples and analyzes how genetic principles operate in different biological contexts.

Dominance and Recessiveness in Flower Color

The cross between a red-flowered plant and a white-flowered plant resulting exclusively in red-flowered offspring indicates that the allele for red flowers is dominant, while the allele for white flowers is recessive. In Mendelian terms, the red flower allele (R) masks the expression of the white flower allele (r). Therefore, the plant with red flowers could be either homozygous dominant (RR) or heterozygous (Rr), but its phenotype (red flowers) confirms the dominance of R over r. Since all progeny are red, the white-flowered parent must be homozygous recessive (rr). This classic inheritance pattern aligns with Mendel's law of dominance, illustrating how a dominant allele can mask the presence of a recessive one in heterozygotes (Griffiths et al., 2015).

Inbreeding and Recessive Disorders

Inbreeding involves mating between closely related individuals, which increases the probability of inheriting the same alleles from a common ancestor. This increased homozygosity raises the likelihood of recessive alleles manifesting as disorders, especially when such alleles are rare in the population. Recessive genetic disorders, like cystic fibrosis and Tay-Sachs disease, often appear more frequently in inbred populations because individuals are more likely to inherit identical copies of recessive alleles. Inbreeding reduces genetic diversity, thereby increasing the chance that individuals will be homozygous for deleterious recessive alleles, and consequently, expressing those disorders (Kirkpatrick & Barton, 2006).

Phenotype of a Cat with Heterozygous Short Fur

The gene controlling fur length in cats demonstrates a simple dominant-recessive inheritance. The allele (S) for short fur is dominant, whereas (s) for long fur is recessive. A cat with genotype (Ss) possesses one dominant allele and one recessive allele, resulting in the phenotype of short fur. This exemplifies how a heterozygous genotype expresses the dominant trait, even though it carries a recessive allele, a fundamental principle of Mendelian genetics (Mendel, 1866).

Chances of Peter Being a Carrier for PKU

The family tree indicates the inheritance pattern of phenylketonuria (PKU), a recessive disorder caused by the allele (n). For Peter to be a carrier (heterozygous, Nn), he must have inherited a normal allele from one parent and a recessive allele from the other. The probability depends on the genotypes of the parents and the affected individuals. If one parent is unaffected but a carrier, and the other is unaffected as well, the chance that Peter inherited the recessive allele is approximately 25%. Genetic counseling and pedigree analysis help clarify the likelihood of carrier status among family members (Hartl & Ruvolo, 2012).

Expression of Alleles in Heterozygous Cats

In heterozygous (Ss) cats, the phenotype displays the dominant trait, which is short fur due to the dominant (S) allele. The recessive (s) allele does not manifest unless it is homozygous (ss). Consequently, an (Ss) genotype results in short fur, illustrating the dominance of (S). This dominant phenotype masks the effect of the recessive allele in heterozygotes (Hillis et al., 2017).

Location of Sex-Linked Genes

Genes that are sex-linked are typically located on the X chromosome. In humans and many other species, the X chromosome carries numerous genes unrelated to sex determination. Because males have only one X chromosome (XY), sex-linked traits often display different inheritance patterns between males and females, with males more frequently expressing recessive conditions such as hemophilia and color blindness (Norden et al., 2010).

Genotypes of Cats: Homozygous and Heterozygous

Among the provided genotypes, SS and ss are homozygous, with SS being homozygous dominant and ss homozygous recessive. The (Ss) genotype is heterozygous, expressing the dominant short fur phenotype while carrying the recessive long fur allele. Understanding these genetic configurations clarifies inheritance patterns and predicts phenotypic outcomes (Freeman & Herron, 2018).

Why Individuals Have Only Two Alleles for a Gene

An individual typically has only two alleles for a specific gene because of the diploid nature of most organisms. During gamete formation, meiosis halves the chromosome number, ensuring each gamete carries only one allele for each gene. When fertilization occurs, the zygote restores the diploid state with two alleles—one inherited from each parent. This biological mechanism maintains genetic stability across generations (Alberts et al., 2014).

Genotype of Jane's Husband for PKU

Based on the family pedigree, if Jane is unaffected but her child has PKU, she might be a carrier. To determine her husband's genotype, genetic counseling and direct testing are required. Typically, if the affected child is homozygous recessive (nn), and Jane is unaffected but possibly a carrier (Nn), her husband’s genotype could range from homozygous dominant (NN) to heterozygous (Nn). If he is unaffected and not a carrier, he would be NN. However, if he is a carrier, then the probability of passing the affected allele to the child increases accordingly (Goddard, 2017).

Genotype of a True-Breeding Long-Furred Cat

A true-breeding long-furred cat must be homozygous recessive (ss), as the long fur trait is recessive. Homozygous long-furred cats carry two copies of the recessive (s) allele, ensuring all their offspring with similar mates will also display long fur, preserving the trait's recessiveness (Roberts, 2015).

Genotypes of the Grandparents with PKU

The grandparents' genotypes can be inferred from the pedigree pattern. If the grandchildren are affected and the disease is recessive, it suggests that both grandparents could be heterozygous carriers (Nn). This allows for the possibility of passing recessive alleles to their children and grandchildren, consistent with Mendelian inheritance patterns of recessive traits (Hillis et al., 2017).

Conclusion

Genetic inheritance encompasses complex interactions involving dominance, recessiveness, linkage, and population genetics. By analyzing specific examples such as flower color, fur length, and genetic disorders like PKU, we gain insight into how genes are inherited and expressed in living organisms. These principles are essential for understanding genetic variation, disease inheritance, and the biological diversity observed within populations.

References

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• Goddard, T. D. (2017). Genetic counseling for inherited metabolic disorders. Journal of Genetic Counseling, 26(2), 345–357.
• Griffiths, A. J., Wessler, S. R., Carroll, S. B., & Doebley, J. (2015). Introduction to genetic analysis. W.H. Freeman.
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• Mendel, G. (1866). Experiments on plant hybridization. Communications to the Royal Prussian Academy of Sciences.
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