Drosophila Ausomal and Sex-Linked Cross Essay

Gregor Mendel theorized that certain combinations of alleles in a genotype would result in a specific ratio of phenotypes expressed in each generation. For example, in the case of the dominant heterozygous anthocyanin genotype, the P1 with (ANL/anl) crossed with the P2 (ANL/anl) would result in a 1:2:1 ratio for genotypes (ANL/ANL), (ANL/anl) and (anl/anl). However,

It was decided that there would be 80 vestigial flies and 20 wild type flies to total to an initial population of 100 drosophila. Next, the flies were anesthetized flies using Fly Nap. The flies were counted out to reach desired ratio, sexing the flies making sure there are equal amounts of males and females to be sure there is ample individuals to allow successful mating. The fly’s food was prepared by taking a frozen rotten banana, cutting it in half, mashing up the banana meat, and mixing yeast into it. The

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.

We started out with three populations; B, D, and G. In order for us to properly create controlled genetic crosses, we had to ensure that all the female flies were “virgins”.

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+).

The variables in this lab were different than the average science experiment. Instead of affecting the experiment to prompt different results, we just had F1 generation plants produce offspring so that we could study their specific traits. By looking at the variables, we can determine if they fit the Mendelian ratio and see if genes are linked on a chromosome.

Steps 7-11 were repeated to record the phenotype of the F2 generation and number of male or female flies.

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

Table 2 shows the phenotypes of the F1 flies produced by crossing P1 wild-type males and P1 no-winged females. The results of that cross was that there was fifty nine wild-type females and forty one males. Therefore there was a total of one hundred wild-type flies produced from crossing P1 true breeding wild-type males and P1 true breeding virgin

11. The progeny of a Drosophila female (heterozygous at three loci: y, ct, and w) crossed to a wild type male are listed below:

The farther genes are apart on the chromosome, the more likely they are to crossover. When the genes are close together or to the centromere the chance of crossing over decreases. Based on the amount of recombinant offspring, gene linkage maps can be created and the map units between genes can be created as one map unit is equal to 1% recombination frequency. Crossing over, along with random fertilization and independent assortment during Meiosis I and II allows

The rationale we are using is that we are starting with the parent generation which have one of the mutations we wish to see the offspring. Once we have set aside an appropriate habitat, we are able to confine four mating pairs of D. melanogaster to clean vials so that we can clearly observe what mutations show in

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 F1 generation that we had just decanted was then moved to a dissecting microscope for scoring, this generation included 20 Drosophila flies that we could then inspect for different traits using the microscope (traits being the sex of

Pairs of alternative traits were expressed in the F2 generation on the ratio of ¾ dominant to ¼ recessive (3:1 segregation ratio referred to as Mendelian ratio)