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THE INHERITANCE OF SPECIFIC TRAITS

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					Title: THE INHERITANCE OF SPECIFIC TRAITS Abstract: The purpose of this lab was to be able to predict phenotypic and genotypic ratios of a monohybrid cross, as well as ascertain whether the AO+ gene in the fruit fly Drosphilia Melanogaster is dominant or recessive, and whether it is autosomal or sex-linked. We did not follow the procedure described in the lab manual. Instead we were given the information required to predict the genotypic/phenotypic ratios, as well as determine the specific traits of the genes. From the given information, we were able to conclude that the Aldox gene is autosomal dominant. Introduction: The exercise in this lab shows how genetic research led to the connection of inheritance, and how it provides specific traits to all organisms. Experiments like this were originally directed to the transmission of hereditary factors from generation to generation, this was the basis to the discovery of Mendelian’s laws. Mendel had two laws and they included; The Law of Segregation and The Law of Independent Assortment. The Law of Segregation was discovered by conducting crossing experiments that crossed traits in the blending model of inheritance. The Law of Independent Assortment was Mendel’s second law discovered and states that each pair of alleles separates independently of other pairs of alleles during gamete formation (gametes are the reproductive cells and alleles are alternative versions of a gene). In this specific experiment we are testing whether the chromosomes are autosomes or not. This is an important factor because autosomes are the most common chromosome in the

cell, and they carry genes that are not involved in determining an individual’s sex. Therefore if the mutation is on the autosomal chromosome it doesn’t matter whether it was passed on by the male or female parent. Another important factor is determining which traits are dominate and which are recessive. This is important because traits that are dominate versus recessive have different impacts on the phenotypic inheritance. (Phenotypes are an organism’s physical appearance). I think that the chromosomes are autosomes, I think that the traits are dominate.

Results: The results for the experiment can be represented by the punnett square diagrams presented below. Graph 1 is a basic diagram of genetic crossing; its purpose is to help show how the punnet square diagram works. Graph one is a simple first generation diagram showing the phenotypic traits of a heterozygous organism. Graph two is a first generation (F1) diagram showing the phenotypic and genotypic traits. It also shows the dominate and recessive genes (AO+ being dominate and AO- being recessive) of the organism. Through the first generation in graph two it can be seen that all offspring are dominate, they all have AO+ trait. The phenotypic and genotypic ration is 2:2. Graph three shows the second generation (F2). It shows how if the offspring of F1 were to mate, their offspring would be as shown. The offspring in graph three all have dominate traits except one, the phenotypic ration is 2:1:1, and the genotypic ratio is 1:1:1:1.

X AOA a XAO+ XAOAA Aa A XAO- XAO+ Aa aa a XAO+ Y

Y

XAO+ Y

X AO+

XAO+ Y

X AO+

X AO+ X AO+

XAO+ Y

XAO+

X

AO+

X

AO-

X

AO-

Y

XAO

Discussion: My results and original hypothesizes supported each other; the traits were dominate and the chromosomes were autosomal. Some unexpected fallacies in the experiment included the


				
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Description: The purpose of this lab was to be able to predict phenotypic and genotypic ratios of a monohybrid cross, as well as ascertain whether the AO+ gene in the fruit fly Drosphilia Melanogaster is dominant or recessive, and whether it is autosomal or sex-linked. We did not follow the procedure described in the lab manual. Instead we were given the information required to predict the genotypic/phenotypic ratios, as well as determine the specific traits of the genes. From the given information, we were able to conclude that the Aldox gene is autosomal dominant.