Drosophila melanogaster is recognized as the fruit fly and a very reliable model organism in the scientific world. In genetics they are utilized to study genetic mechanisms in order to understand genetic inheritance patterns in other biological organisms. Fruit flies are the ideal model organism because they are cost effective, have short life spans, are easy to maintain and produce a sizable progeny. The fruit fly experiment is conducted to observe how Mendelian extensions and basic principles affect fruit fly progenies from generation to generation. Mendel’s law of dominance suggests that recessive alleles are overpowered by a stronger, dominant allele. For example, a cross between a homozygous dominant and homozygous recessive allele will …show more content…
The law of independent assortment is an extension to the law of segregation and states that when numerous traits are acquired they will assort independently allowing them to occur together. In the experiment performed, which is modeled after Thomas Morgan’s original experiment, the inheritance of sex-linked and autosomal traits were observed. In this experiment it is believed that there is an autosomal trait and sex-linked trait present. The trait believed to be autosomal is being apterous and the sex-linked trait is believed to be the presence of white eyes. The parental cross produces mutant flies, which have no wings and white eyes or white eyes with wings. The P cross is Xw/ Xw ; ap+/ap+ × Xw+Y ; ap/ap due to the wildtype being dominant and white eyes being X-linked and being apterous is an autosomal trait that showed up in the F2 generation. Sex-linked traits will not assort independently and autosomal will assort independently because they are not …show more content…
Table 2 is the first fly count of my individual fly count and is a result of the emergence of the F2 generation. To analyze if the hypothesis made is true a chi square analysis was done and is table 3. Based on the chi it is evident that the hypothesis has to be reject considering that the chi square number is quite high. To figure this out for all the fly counts including the group 3 complete count the degrees of freedom were calculated. To calculate the degrees of freedom the number of levels of one categorical value are identified. There is two genders, male and female so this provides the first part: (2-1). Then the next number of variables for the next category are determined which are the 4 phenotypes observed so, (4-1). Finally the degrees of freedom are calculated, (2-1) × (4-1) = 3 D.F. Three degrees of freedom are present. The critical value for three degrees of freedom is 7.81 and the values provided by all chi squares are very high compared to the critical value and this forces the group to reject the
Variation in selection pressures on the goldenrod gall fly and the competitive interactions of its natural enemies
In order to figure out the genes responsible, there are several other factors that must be determined. These factors include the number of genes involved, if each gene is x-linked or autosomal, if the mutant or wild-type allele for each is dominant, and if genes are linked or on different chromosomes. Proposed crosses include reciprocal crosses between the pure-breeding mutants of strains A and B with the wild-type will help determine if the genes or sex-linked or autosomal, in addition to which alleles are dominant (8). Another proposed cross includes complementation crosses between pure-breading mutants from strains A and B to determine if one or two genes are involved (8). Furthermore, testcrosses between F1 progeny and pure-breeding recessive mutants from strains A and B, which will help determine if genes are linked on the chromosome or if they assort independently (8). These proposed crosses are shown in the attached
The purpose of our experiment was to test whether or not the Wisconsin Fast Plants, or Brassica rapa, followed the Mendelian genetics and its law of inheritance. First, after we crossed the heterozygous F1 generation, we created an F2 generation which we used to analyze. After analyzing our results, we conducted a chi-square test for for both the F1 and F2 generations to test their “goodness of fit”. For the F1 generation we calculated an x2 value of 6.97, which was greater than the value on the chi-square table at a p-value of 0.05 and 1 degree of freedom (6.97 > 3.84). This meant that we had to reject our hypothesis that stated there would be no difference between the observed and expected values. This showed us that the F1
Test 4: All three phenotypic frequencies saw a reduction in their number as the homozygote fishes saw a reduction in their number and were not able to pass on their alleles to create either their colored fish or a heterozygote. Both yellow and blue allele frequencies decreased by the same
Conclusion for class di-hybrid cross: The p value 0.779 is in the non-significant range in the chi square table. The null hypothesis is therefore correct. Sepia eyes and vestigial wings in the flies is a mutation in the genes that is not linked meaning it is a product of independent assortment.
Introduction: The purpose of this laboratory activity is to investigate the Hardy-Weinberg Law of Equilibrium using the fruit fly Drosophila melanogaster. According to the Hardy-Weinberg Law of equilibrium, allele frequencies should remain the same in large populations that do not experience gene flow, mutations, nonrandom mating, and natural or artificial selection. We will be studying the alleles that determine wing shape, either normal (wild type) wings or vestigial wings.
The F2 punnett square shows that there should not be a female fly that has apterous wing mutation. Our observed experiment showed that female flies are capable of forming in the F2 Generation. Therefore, the mutation is located on autosomal chromosomes. In trial 1, the p value is not significant. This could be due to the fact that the male to female ratio in the F1 generation was unequal. In trial 2, the p value is significant and likely due to chance. The probability error is between 1 % and 5%.
This would produce 100% of the dominant phenotype in females with 50% carrying the recessive trait.
An individual can be homozygous dominant (two dominant alleles, AA), homozygous recessive (two recessive alleles, aa), or heterozygous (one dominant and one recessive allele, Aa). There were two particular crosses that took place in this experiment. The first cross-performed was Ebony Bodies versus Vestigle Wings, where Long wings are dominant over short wings and normal bodies are dominant over black bodies. The other cross that was performed was White versus Wild where red eyes in fruit flies are dominant over white eyes. The purpose of the first experiment, Ebony vs. Vestigle was to see how many of the offspring had normal bodies and normal wings, normal bodies and vestigle wings, ebony bodies and normal wings, and ebony body and vestigle wings.
When trying to understand genetics Mendel 's laws are a very big part of it. Mendel 's two laws help us understand and analyze genetic crossings. In our experiment we used drosophila melanogaster flies, a common fruit fly. This was perfect to understand and visualize how the laws take effect. Mendel stated that during the process of genetic crossing; two alleles are formed which then separated to form gametes, which would appear in fertilization. In our experiment we accomplish a cross that determined different eye and body colors. By using the Chi-Square test, we were able to test our results. Our groups hypothesis stated the number of flies from the F2 generation would accommodate Mendelian Genetic Ratio of 9:3:3:1. Our Chi-Square test results
Multiple allele is when more that one allele is being crossed and all of the traits are being crossed together. Sex linked inheritance is when the gene for a certain trait is carried on either the X or Y chromosomes for the parent. The goal of this lab is to better understand genetics. The guiding question is, Which model of inheritance best explains how a specific trait is inherited in fruit flies? In first population, the model of inheritance was dominant-recessive and the wild body type is dominant and the aristapedia body type is recessive.In the second population, the model of inheritance is incomplete dominance because the mellow trait crossed with the hyper trait combines to make the spontaneous trait. In the third population, the model of inheritance was sex linked recessive to the yellow colored trait on the X chromosome. In the fourth population, the model of inheritance was a multiple allele autosomal cross for the different traits.
Mendel’s law of segregation states that offspring receive only one of two alleles of a gene from the parent (Brooker et al. 2014). This means that utilizing a monohybrid cross where each parent has both a dominant allele of a gene and a recessive allele, that by producing offspring of these plants, a predictable outcome of trait inheritance should be observed (Brooker et al. 2014). This experiment investigated the inheritance of anthocyanin in Brassica rapa.
If one wanted to know their chance of carrying or having the disease creating a punnet square could help determine that. A normal person without Albinism or the presence of the allele melanin can be represented by capital “A” and another allele that represents the lack of melanin will be represented with lower case “a”. Since Albinism is an autonomic recessive disease, this means a person with a homozygous recessive gene will have the disease. Both parents must be heterozygous dominant and carry the allele; they will have a 25% chance of having a child with albinism and a 70% chance of having a child carrying the disease. If one parent is heterozygous that still carries the flawed gene and the other parent is homozygous dominant there will be a 50% chance their child will carry the disease but wont have a child with Albinism.
The exercise involved a series of ‘mating’ events resulting in 6 generations. Each mating event produced offspring with ‘possible’ newly inherited traits. The idea of ‘chance’ was included through simple coin tosses. Also, ideas of selection and mutations were introduced into the ‘gene pool’, which presented a deeper and more clear understanding of Mendelian inheritance and the Hardy-Weinberg equilibrium. Upon reaching the third generation, A B1 mutant allele was introduced to the blue locus-influencing fin shape and a G1 mutant allele was introduced to the green locus-influencing Mouth
On the other hand, the authors found that linkage disequilibrium (LD) between SNP and CNP was not much different from that between two SNPs. The authors demonstrated that an increased mutation rate and larger number of segregating alleles hardly affects LD with a nearby SNP.