Dominant and recessive genes

Dominant and recessive genes

Introduction

Physical traits are human characteristics that are easily observable and are determined by specific segments of DNA called genes. Alleles are variations in the human genes usually two in number but in rare cases can be more than two. An individual may inherit two identical or two different alleles from their parents. When two different alleles are inherited and are present, the traits due to dominant alleles are always observed in the individual, even when a recessive allele is present. Traits due to recessive alleles can only be observed when two recessive alleles are present they interact in specific ways. In other words the dominant allele are more stronger than the recessive allele since they can produce a trait on their own but on the other hand the recessive allele ahs to be more than one for their traits to be observable.

With the aim of proving the truth in the theory stating that in women, having an index finger that is shorter than the ring finger is a recessive trait, whereas in men, having a shorter index finger is dominant, an experiment that involved comparison of the index finger and the ring finger in both men and women was conducted in three women and two men.

A T-Grid was drawn on a piece of paper and the right hand of each participant placed on the grid in such a way that the middle finger lied on the vertical axis of the grid while the tip of the ring finger lied on the horizontal axis of the grid. If the index finger lied below the horizontal axis of the grid, then the phenotype of the participant was considered short index fingered. The opposite was true if the index finger was found to lie on or above the horizontal axis of the grid. That is, long index finger.

Findings

Out of the five participants three of which were female and two male, it was observed that the two of the female had a longer index finger than the ring finger; one female had a shorter index finger compared to the ring finger while the male had a shorter index finger than the ring finger.

The index finger length is usually considered a sex influenced trait. The dominant allele produces a short index finger compared to the ring finger in men while in women the dominant allele produces a index finger which is longer or equal to the ring finger. In women two short index finger allele is required to produce a short index finger compared to the ring finger. The genes in not likely to be found in the x chromosome. in men two long ring finger allele is needed to produce a longer ring finger compared to the index finger.

Conclusion

From the result of the experiment is true that women will always have a longer index finger than the ring finger as opposed to the case in men where the index finger is always smaller than the ring finger. In cases where women have a shorter index finger than the ring finger , its is due to the recessive short index finger gene while in men longer ring finger trait is dominant. In other words women, having an index finger that is shorter than the ring finger is a recessive trait, whereas in men, having a shorter index finger is dominant.

Works cited.

Rostand, J and Tétry, A . An Atlas of Human Genetics .1964

Molly, M. All about Allergies. The Nemours Foundation 2003

Luisa, S .Biology success; teaching advance learners.1976