I. Introduction.
(Start with drosophila as a model organism)
Drosophila melanogaster (D. melanogaster), the fruit fly, has proven to be an invaluable model organism that’s been used to study many genetic phenomena, including X-linked inheritance, gene mapping, and autosomal inheritance [1]. D. melanogaster has been used as a model organism for over 100 years, and its genome (containing ~14,000 genes) has been well-studied, thus making it ideal as a model organism. As with most of the long-established model organisms, practicality is key. D. melanogaster has a simple diet, and the life cycle is relatively short, so large-scale crosses can be followed through many generations [2].
(How drosophila will be used in crosses)
As previously mentioned, D. melanogaster has been used extensively in genetic studies, which is what we plan to utilize them for in our lab. There are many ways that fruit fly DNA can be mutated to create visible traits, called phenotypes [3]. In our lab, we used the strains lobe, eyeless, sepia, white, and wild-type, we to performed crosses and reciprocal crosses to determine if the corresponding phenotypes were autosomal-linked or X-linked traits. The Lobe strain exhibits a smaller eye than wild-type, caused by a mutation in the optic lobe of the brain. The eyeless mutation makes it so D. melanogaster does not make eyes during development [3]. Lastly, the sepia strain of D. melanogaster exhibits a sepia pigment in the eyes of the organism [4], while white strain has a deletion of genes responsible for making the red pigment observed in wild-type eyes, so appear white. It should be noted that the white mutation is located on the sex chromosome, meaning males and females have different numbers of copies of...
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..., we produce a summary of every possible combination of parental alleles to determine dominance and, thus, phenotype.
(Objectives of why we are studying = to learn several concepts such as autosomal inheritance, X-linked inheritance, and gene mapping)
Overall, we are studying D. melanogaster to expand our knowledge in the field of genetics and molecular biology. More specifically: autosomal inheritance, X-linked inheritance, and gene mapping. The knowledge gained from such experiments can be utilized outside of the classroom in many aspects, for both scientific and practical purposes. A basic understanding of the aforementioned knowledge allows scientists to plan experiments efficiently, be concise in their actions, and make more accurate predictions in the fields of biology. As a biology student, these skills will be useful in whatever field I choose to follow.
Drosophila melanogaster is a model species used commonly for research in the areas of genetics and phylogeny (Kohn and Wittkopp, 2007). Drosophila is a model species due to the abundance of offspring, short generation times, and the ease of identifying wild type vs ebony phenotypes (University of South Florida, 2017, Biodiversity Lab Manual). This experiment is being performed in order to evaluate whether or not a fly culture after 3 generations will conform to the Hardy-Weinberg equilibrium equation. This equation is being used as a null hypothesis and will most likely not be achieved due to the relatively small population of flies being used in the experiment as well as other factors such as genetic drift (Dansereau, 2014). The experiment will take place over seven weeks in which the procedure will alternate between scoring the
Anthocyanin is a purple colored pigment in plants that protect tissue from stressful light conditions (Glover and Martin 2012). This experiment utilized monohybrid crosses of the Wisconsin Fast Plant variety of B. rapa with the F_1 generation having one dominant allele for anthocyanin (ANL) and one recessive allele (anl) (Kinds Plants 2014), to complete their life cycle and produce offspring that were observed for their phenotype. By utilizing the genotype of each parent a prediction for the outcome of these genetic crosses was formulated with a Punnett square (Brooker et al. 2014). Since two alleles need to be existent for a recessive trait to be conveyed, and only one allele for a dominant trait (Morgan and Carter 2008), the offspri...
The idea of the project was to experiment breeding Drosophila Melanogaster (fruit fly) to figure out if certain genes of that species were sex linked or not (autosomal). A mono-hybrid cross and di-hybrid cross was performed. For the mono-hybrid cross, white eyed female and red eyed male were placed in one vial for them to reproduce. For the di-hybrid cross, red eyed and normal winged flies and sepia eyed and vestigial winged flies were placed in their vial to reproduce. In the mono-hybrid cross the results expected were within a 1:1:1:1 ratio. Expected results similar to the expected desired null hypothesis proposed with what the F1 parental generation breeds. The potential results would have had to have been within the ratios of 9:3:3:1. The results were clear and allowed the null hypothesis to be correct. The white eyed gene in the fruit flies is sex linked. Sepia eyes and vestigial wings are not sex linked and are examples of independent assortment.
The fruit fly, or the Drosophila melanogaster, was used in this experiment to study patterns of inheritance. It only takes a fruit fly 14 days to develop from an egg to an adult and then 12 hours before they become reproductive, so these factors made the fruit fly a good species to study, because we had enough time to do crosses. We were investigating the patterns of inheritance in the eye color and the wings. The wild type flies had red eyes and full wings, while the mutant phenotype had brown eyes and no wings. We also had to study the sexes of the flies. The male flies had darker abdominal tips and sex combs on both of their forearms. For the results, my group had predicted as follows:
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
The major topic of this experiment was to examine two different crosses between Drosophila fruit flies and to determine how many flies of each phenotype were produced. Phenotype refers to an individual’s appearance, where as genotype refers to an individual’s genes. The basic law of genetics that was examined in this lab was formulated by a man often times called the “father of genetics,” Gregor Mendel. He determined that individuals have two alternate forms of a gene, referred to as two alleles. An individual can me homozygous dominant (two dominant alleles, AA), homozygous recessive, (two recessive alleles, aa), or heterozygous (one dominant and one recessive allele, Aa). There were tow 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.
17. Fruit flies normally have eight chromosomes. The diagram below shows the result of meiosis in three fruit flies to produce gametes with the number of chromosomes indicated. The male then mates with both female A and female B to produce three zygotes (1, 2, and 3).
From simple heredity experiments with garden peas, to cloning sheep, the field of genetics has come a long way. Now we are closer to mapping out the human genetic map due to advances in technology, and years and years of research. Perhaps the most influential and groundbreaking scientist, Gregor Mendel, he was responsible to provide a path to where genetics is now today with his experiments of garden peas.
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.
Drosophila melanogaster are great model organisms for the study of genetics. This is because there are approximately 16,000 genes observed in fruit flies and we observe much homology in the genomes of fruit flies and humans. For example, “75% of know human disease genes have a recognizable match in the genome of fruit flies” (Xeniya Rudolf, Lecture 8, slide 3).
We have known for centuries that traits are passed from parents to offspring. What has not always been understood is how traits are determined. One explanation that appealed to scientist for many centuries was that traits of parents were blended, or mixed in offspring. The blending hypothesis accounted for many observable traits and was widely accepted for many years. However, the idea of blending could not account for the appearance of unexpected traits in some offspring. It was not until scientist discovered the cellular basis of life that the inheritance of traits was better understood.
The data obtained confirms that there is a significant difference in expected and obtained allele frequencies, which results in the conclusion that the populations of fruit flies disrespect the Hardy-Weinberg equilibrium because of the sexual selection and/or genetic drift genetic factors. The system is closed; meaning that there is no migration, nor gene flow and natural selection, due to how no offspring die off from a lack of reproductive fitness. Moreover, mutation is not a disruptive force here, since it seems that there is no harsh environmental conditions that would bring about such an effect. Under small populations, the visible impacts of genetic drift can be observed. The small population size of the fruit flies reflects how random chance of genetic drift caused the significant difference conclusion of our
Based on our data, apterous is a gene that is located on the autosomal chromosomes of Drosophila melanogaster. Based on the degree of freedom, the probability is due to chance. The probability error 1% and 5%. It cannot be located on the sex chromosome because there were females in the F2 generation that showed characteristics of apterous, but according to the punnett square there should not be any females with apterous in the F2 generation.
Taylor, J., Loney, B. R., Bobadilla, L., Loacono, W.G., & McGue, M. (2003). Genetic and
...ary part in genotypes of potential interest that human geneticists breeders, as well as evolutionary geneticists are investigating. However, although we have the capability to unravel experiments that the founders of quantitative genetics would have never imagined, but their basic, un-computational machinery that they developed is most easily adaptable to the latest analyses that will be needed. We are far from ‘letting-go’ molecular biologists from the mathematical techniques/systems, because this age in respect to genomics has been forced into accepting gratitude due to the major importance of quantitative methods as opposed to the new molecular genetics. As geneticists tend to map molecular variation as well as genomic data, quantitative genetics will be moving to the front position because of its relevance in this age of rapid advancement in molecular genetics.