Fly lab experiment
- 1. Kohshi Gokita IB Biology HL Per. 5 Fly Lab Introduction: In this investigation of fly lab, this is based on genetics and gives realistic ratios when crosses are performed. This lab was according to Thomas Hunt Morgan, so you must be like real geneticist to work on this lab. At first, you have to find for dominant allele, which is powerful gene in crossing. So the appearances or features are often be same as dominant gene’s features. On the other hand, there is another type of allele, called recessive. It is weaker than dominant. All the appearance of organism are referred in phenotype, which expresses how the organisms look like. And genotype expresses traits of alleles. According to Mendel, the gene which contains two same alleles are called homozygous, and the off springs which are produced from homozygous pairs are called F1 generation. From the F1 generation, the gene which contains different alleles are produced and they are called heterozygous. And if you cross the F2 generation, it is expected that the ratio of off spring will be 3:1 in monohybrid cross. In dihybrid cross, the ratio of 9:3:3:1 is expected. Thus, in this investigation, you find dominant alleles, recessive alleles, sex-linked recessive alleles, dihybrid allele, and dominant lethal allele. And you check the reliability of the data by using chi-square. Data Collections (total 5 crosses alleles) Dominant Allele: Wild vs. Eye Shape Lobe F1 generation Results of Cross #1 Ignoring Sex Parents (Female: L) x (Male: +) Offspring Phenotype Number Proportion Ratio L 1018 1.0000 1.000
- 2. Total 1018 *According to data, it shows that eye shape lobe fly mated with wild type eye shape. It reveals that the gene of eye shape lobe is dominant allele over gene of wild type eye shape because that off spring of F1 generation are all fly of eye shaped lobe. L=eye shape lobe +=wild type LL x ++ + + L L+ L+ L L+ L+ Genotype = L+ Phenotype = all’s eye shapes are lobe. F2 generation Results of Cross #2 Ignoring Sex Parents (Female: L) x (Male: L) Offspring Phenotype Number Proportion Ratio + 242 0.2490 1.000 L 730 0.7510 3.017
- 3. Total 972 Chi Square Hypothesis Using Cross #4 Ignoring Sex Phenotype Observed Hypothesis Expected Chi-Square Term + 242 710.0000 690.1200 290.9806 L 730 290.0000 281.8800 712.4008 Total 972 1000.0000 972.0000 1003.3814 Chi-Sqaured Test Statistic = 1003.3814 Degrees of Freedom = 1 Level of Significance = 0.0000 Recomendation: Reject your hypothesis *Finally, it supported that eye shape lobe is dominant allele over wild type eye shape. In the F1generation, all of the genotypes were heterozygous of L+. L is dominant over +, so all the phenotypes in F1 generation became eye shaped lobe. However, in F2 generation, to cross with the two heterozygous genes of L+, the off spring becomes eye shaped lobe fly and wild type eye shape. So the ratio is 3:1. L+ x L+ L + L LL L+ + L+ ++ Genotype = LL: L+ : ++ = 1:2:1
- 4. Phenotype = eye shape lobe : eye shape lobe : wild type Recessive allele: Wild vs. Incomplete wing vein F1 generation Results of Cross #1 Ignoring Sex Parents (Female: RI) x (Male: +) Offspring Phenotype Number Proportion Ratio + 941 1.0000 1.000 Total 941 *According to data, it shows that type of incomplete wing vein mated with wild type wing vein. It reveals that the gene of incomplete wing vein is recessive allele under gene of wild type wing vein because that off spring of F1 generation are all wild type wing vein. RI = incomplete wing vein + = wild type wing vein RIRI x ++ RI RI + +RI +RI + +RI +RI Genotype = +RI
- 5. Phenotype = wild type wing vein F2 generation Results of Cross #2 Ignoring Sex Parents (Female: +) x (Male: +) Offspring Phenotype Number Proportion Ratio + 763 0.7502 3.004 RI 254 0.2498 1.000 Total 1017 Chi Square Hypothesis Using Cross #2 Ignoring Sex Phenotype Observed Hypothesis Expected Chi-Square Term + 763 700.0000 711.9000 3.6679 RI 254 300.0000 305.1000 8.5585 Total 1017 1000.0000 1017.0000 12.2265 Chi-Squared Test Statistic = 12.2265 Degrees of Freedom = 1
- 6. Level of Significance = 0.0005 Recommendation: Reject your hypothesis *Finally, it supported that incomplete wing vein is recessive allele under wild type wing vein. In the F1generation, all of the genotypes were heterozygous of +RI. + is dominant over RI, so all the phenotypes in F1 generation became wild type wing vein. However, in F2 generation, to cross with the two heterozygous genes of +RI, the off spring becomes incomplete wing vein fly and wild type wing vein. So the ratio is 1:3. +RI x +RI + RI + ++ +RI RI +RI RIRI Genotype = ++ : +RI : RIRI = 1:2:1 Phenotype = wild type wing vein to incomplete wing vein = 3:1 Recessive sex-linkedallele: Wild vs. forked bristle F1 generation Results of Cross #1 Parents (Female: +) x (Male: F) Offspring Phenotype Number Proportion Ratio Female: + 476 0.4779 1.000 Male: + 520 0.5221 1.092 Total 996
- 7. *According to data, it shows that forked bristle fly mated with wild type bristle. It reveals that the gene of forked bristle is recessive allele under gene of wild type bristle because that off spring of F1 generations are all wild type bristle. + = wild type bristle F = shaven bristle ++ x FF + + F +F +F F +F +F Genotype = +F Phenotype = wild type bristle F2 generation Results of Cross #2 Parents (Female: +) x (Male: +) Offspring Phenotype Number Proportion Ratio Female: + 518 0.5005 2.072 Male: + 267 0.2580 1.068 Male: F 250 0.2415 1.000 Total 1035
- 8. Chi Square Hypothesis Using Cross #6 Phenotype Observed Hypothesis Expected Chi-Square Term Female: + 518 500.0000 517.5000 0.0005 Male: + 267 250.0000 258.7500 0.2630 Male: F 250 250.0000 258.7500 0.2959 Total 1035 1000.0000 1035.0000 0.5594 Chi-Sqaured Test Statistic = 0.5594 Degrees of Freedom = 2 Level of Significance = 0.7560 Recomendation: Do not reject your hypothesis *Finally, it supported that forked bristle is recessive allele under wild type bristle. And it can be also defined in sex linkage. In the F1generation, all of the genotypes were heterozygous of +F. + is dominant over F, so all the phenotypes in F1 generation became wild type bristle. However, in F2 generation, to cross with the two heterozygous genes of +F, the only male off spring became forked bristle. So, it represents that female is carrier of the gene of forked. Female off springs do not become forked bristle. Female +F x Male +F X+ XF X+ X+X+ X+XF YF X+YF XFYF Genotype = X+X+ : X+XF : X+YF : XFYF = 1 : 1 : 1 : 1 Phenotype = female wild : male wild : male forked bristle = 2 : 1 : 1
- 9. Dihybrid allele: Wild vs. eye shape Lobe and bristle Forked F1 generation Results of Cross #1 Ignoring Sex Parents (Female: +) x (Male: F;L) Offspring Phenotype Number Proportion Ratio L 1028 1.0000 1.000 Total 1028 Explanation: According to data, male fly which contains gene of forked bristle and lobe eye shape mated with wild type female fly. This data shows that the forked and love are dihybrid cross. It is because that heterozygous genes are crossed together. += wild type body color FL= curve and incomplete +C x FLFL + + FL FL+ FL+ FL FL+ FL+ Genotype of the offspring = FL+ Phenotype of the offspring = eye shape lobe
- 10. F2 generation Results of Cross #2 Ignoring Sex Parents (Female: L) x (Male: L) Offspring Phenotype Number Proportion Ratio + 180 0.1818 2.769 F 65 0.0657 1.000 L 543 0.5485 8.354 F;L 202 0.2040 3.108 Total 990 Chi Square Hypothesis Using Cross #10 Ignoring Sex Phenotype Observed Hypothesis Expected Chi-Square Term + 180 200.0000 198.0000 1.6364 F 65 100.0000 99.0000 11.6768 L 543 500.0000 495.0000 4.6545 F;L 202 200.0000 198.0000 0.0808 Total 990 1000.0000 990.0000 18.0485
- 11. Chi-Sqaured Test Statistic = 18.0485 Degrees of Freedom = 3 Level of Significance = 0.0004 Recomendation: Reject your hypothesis Explanation: According to the data, it proved that lobe eye shape and forked bristle are dihybrid cross. In F1 generation, the phenotypes are all forked bristle but in F2 generation, the ratio of wild type, lobe eye shape, and forked bristle became 9:3:3:1. F = Forked bristle L = lobe eye shaped FfLl x FfLl FL Fl fL fl FL FFLL FFLl FfLL FfLl Fl FFLl FFll FfLl Ffll fL FfLL FfLl ffLL ffLl fl FfLl Ffll ffLl Ffll Genotype =FFLL : FFLl : FfLL : FFll : FfLl : ffLL : Ffll : ffLl : ffll = 1: 2:2:1:4:1:2:2:1 Phenotype = lobe/forked : lobe : forked : wild type =9:3:3:1 Dominant lethal allele: Aristapedia male vs. Aristapedia female F1 generation Results of Cross #1
- 12. Ignoring Sex Parents (Female: AR) x (Male: AR) Offspring Phenotype Number Proportion Ratio + 362 0.3539 1.000 AR 661 0.6461 1.826 Total 1023 *This is the data of male fly with aristapedia antenna and female fly with aristapedia antenna mated together. This data shows the ratio of wild type and antenna aristapedia, which is 1:2. The wild type genotype ++ is impossible to produced in this dominant lethal because it refers to death. AR = Aristapedia += wild type AR+ x AR+ AR + AR ARAR AR+ + AR+ ++ death Genotype = ARAR : AR+ : ++ (death)= 1:2 Phenotype = Aristapedia : wild type = 2:1 F2 generation Results of Cross #2
- 13. Ignoring Sex Parents (Female: +) x (Male: +) Offspring Phenotype Number Proportion Ratio + 1019 1.0000 1.000 Total 1019 Chi Square Hypothesis Using Cross #27 Phenotype Observed Hypothesis Expected Chi-Square Term Female: + 524 500.0000 509.5000 0.4127 Male: + 495 500.0000 509.5000 0.4127 Total 1019 1000.0000 1019.0000 0.8253 Chi-Sqaured Test Statistic = 0.8253 Degrees of Freedom = 1 Level of Significance = 0.3636 Recomendation: Do not reject your hypothesis *According to data, it reveals that aristapedia male mates with aristapedia female will be dominant lethal allele. In F1 generation, their dominant allele of wild type kills pair up and died, so that is why the ratio was 2:1 of aristapedia and wild type, but in F2 generation, the result was different. The F1 generation crosses together, it produced only wild type off springs.
- 14. AR= aristapedia + = wild type AR+ x ++ AR + + AR+ ++ + AR+ ++ Genotype = AR+ : ++ = 1:1 Phenotype = aristapedia : wild type = 1:1 Failed Crosses; Dominant allele wild type vs. star eye shape Recessive allele----- Recessive sex-linked allele----- Dihybrid Crosswild type vs. eye less & curly wing wild type vs. eye color sepia & miniature wing wild type vs. body color ebony & aristapedia antenna Dominant Lethal Alleleeye color brown vs. wing size apeterous eye shape bar vs. eye color purple body color yellow vs. wing shape curved