Title: Locating a Mutant Gene in Its Chromosome Using a Drosophila Model
Abstract: Genetics is the study of genes, heredity and variation in living organism. It is important in understanding how heritable traits are passed down from one generation to another. Here in this study, the identification of a particular mutation was explored by discovering how it is transmitted and where it is located. Drosophila melanogaster, a species of fruit flies, was the model used to illustrate the process of gene inheritance. Virgin female fruit flies were collected over a span of two- three weeks and crossed with balancer chromosome male fruit flies. The progeny, also known as the F1 generation, was then used to perform a test cross. The test cross was done between an F1 male and a virgin female from the parental generation. The results of the test cross, determined the mutation as well as which chromosome it was located on.
Introduction: When studying the principles of genetics, an ideal model organism used is the Drosophila
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The mutation of these flies were unknown. This vial served as the parental generation. The parents were left to mate and then transferred to a new a vial. Virgin females were then collected and kept in a separate vial. The female virgins were then crossed with balancer chromosome male flies.
The progeny of this cross were known at the F1 generation. Phenotypes seen in this cross were recorded. Males from this cross were collected. A male that with a different phenotype from the mutation in the mutant flies was selected. (If the mutation in the mutant flies is white-eye, a male without an eye mutation is selected.) The selected male from the F1 generation is then crossed with a virgin female from the parental generation. After which, the phenotypes seen were recorded and used to determine which chromosome the mutation is located on and what the mutation is.
The parents are both homozygous. The homozygous dominant would represent the wild type. And the homozygous recessive would represent the other fly parent of a different strain. The F1 generation would consist of 100% Wild Type but they would all be heterozygous in carrying the recessive gene.
To set up this experiment, two twenty-five gallon aquariums, 3 petri-dishes, 200 flies, rotten bananas, and yeast were used. The bananas chosen to be an accelerant for the growth of the yeast and were frozen so they would be easier to cut. The yeast was used because the drosophila melanogaster prefer this as a food source. The vestigial and wild type flies were sexed (to determine their sex), sorted, and counted. An initial population size of 100 total flies was decided so that it would be easier to determine the phenotypic percentage of the total population. Fly paper was placed in one of the sets of cages to impose a method of natural selection as well as the sexual selection which is being solely tested by the other set of cages.
This process of P-element mobilization is the basis of how we directed recombination in male flies, and therefore the basis of generating deletions in the DMAP1 gene. We made several crosses that allowed P-element mobilization to occur in male flies by crossing P-element strains (non-autonomous) to a transposase source, producing heterozygous flies containing a P-element and a transposase source, and therefore allowing us to induce and detect male recombination events in progeny. The specific recombination event of interest is when the P-element is mobilized towards the right onto a homologue, which may have induced a deletion in
Introduction: The intention of this lab was to gain a better understanding of Mendelian genetics and inheritance patterns of the drosophila fruit fly. This was tasked through inspecting phenotypes present in the dihybrid crosses performed on the flies. An experimental virtual fly lab assignment was also used to analyze the inheritance patterns. Specifically, the purpose of our drosophila crosses is to establish which phenotypes are dominant/recessive, if the traits are inherited through autosome or sex chromosomes and whether independent assortment or linkage is responsible for the expressed traits.
The conducted experiment assists in determining an unknown mutant allele found in Drosophila melanogatser. Mutant 489 illustrates a defect in eye pigmentation, which displays a dark brown eye color verses the brick red eyes in wild type flies. Based on the appearance our 489 mutation we've names our mutant rust.
The motivation of this lab report is to use Mendel’s Laws of Inheritance to analyze and predict the genotypes and phenotypes of an offspring generation (F2) after knowing the genotypes and phenotypes of the parent generation (F1). The hypothesis for this experiment is that the mode of inheritance for the shaven bristle allele in flies is autosomal recessive in both male and female flies.
It would be expected that the mutant F1 flies would be heterozygous for the allele responsible for the grounded trait. If two F1 flies were mated, the percentage of flies that would be expected to be wildtype in the F2 generation would be 25% mutants given that the mutant allele (ap) is predicted to be recessive and, leaving 75% to be wildtype (ap+).
There were eight different phenotypes among the progeny. The highest phenotypic frequency was the w+m+f+ at 40% of the progeny. The lowest was the w+mf+ with only 2 % of the progeny (Table 3). The sum of the recombinant frequencies between genes, table 4, was used to determine the gene distance. The recombinant frequency was determined by counting the number of individuals whose genes differed from that of the parental type. For example, how many individuals white eye gene, and miniature wing gene, differed from both wild-type or both mutants. Recombination occurred between the white and miniature gene 33 times. Recombination occurred between the miniature and the forked genes 31 times. Recombination occurred between the white and forked genes 44 time. Double recombination occurred 10 times. Therefore, genes w and f are 64 m.u. apart, m and w are 33 m.u. apart, and m and f are 31 m.u. apart (Figure
11. The progeny of a Drosophila female (heterozygous at three loci: y, ct, and w) crossed to a wild type male are listed below:
Again the flies were sorted and the first twenty males and twenty females were chosen and their body phenotypes were recorded. The same transfer techniques were used to place the flies in the fresh culture vial. The excess flies were disposed of in the morgue. The allele frequencies and expected heterozygosities at each transfer were
There are easy to culture however, there are insects and doing a step wrong can affect the whole experiment. Before beginning any experiment with the Drosophila people need to learn to identify the certain characteristics and to anaesthetize the flies without killing them. When the flies are mating, the fertilization are more of chance because no one knows for certainty that they are going to have the same number of offspring’s each time. The number of offspring is more of a probability and a certainty. Prediction of the outcomes of the offspring can be
we said goodbye and placed them in the fly morgue. We allowed the F2 larval
For our first generation (F1) of flies we chose to cross apterous (+) females and white-eye (w) males. We predicted that the mutation would be sex linked recessive. So if the female was the sex with the mutation then all females would be wild type heterozygous. Heterozygous is a term used when the two genes for a trait are opposite. The males would all be white eye since they only have one X chromosome. If the males were the sex that had the mutation then all the flies would be wild type but the females would be heterozygous.
The vial was then labeled accordingly with the type of cross (Male Vg, Female W) and the date. The date is important as the Drosophila complete a life cycle within approximately 2 weeks from the mating day. This vial became known as the parent generation or (P).
Heredity – the transmission of traits from one generation to another, from parents to offspring; the protoplasmic continuity between parents and offspring