Genetic Predictions in the Fruit Fly
Kayla Berezne
Mrs. Cohen
Honors Biology
24 March 2013
Genetic Predictions in the Fruit Fly The Drosophila melanogaster is a fruit fly with a very short life cycle. They can be winged or wingless, and have red eyes or white eyes. The different options are called alleles. Alleles are the variants of a specific gene, and one is received from each parent on each chromosome. (“What Are Dominant and Recessive?”). It was chosen to use winged females and wingless males to predict the offspring in this experiment. The winged allele is dominant, meaning it only needs one allele to physically appear. The wingless allele is recessive, which gets covered up by the dominant allele (“Fruit Fly Genetics”). Each trait has two alleles in the flies’ genotype, or genetic makeup. In the parent generation (P), the flies used are homozygous, meaning they have two of the same alleles (“Mendelian Genetics”). The females are winged, and since that is a dominant allele, it is represented by a capital letter F. That means the female genotype is FF, because they get one allele from each parent. The males are wingless, which is a recessive allele represented by a lowercase f. Their genotype is ff. A Punnett square can be used to predict whether their offspring are winged or wingless. The offspring are called the first filial generation (F₁), while their offspring are called the second filial generation, or F₂.
F₁ Generation Punnett Square:
F F
f f
Genotype ratio – FF: Ff: ff – 0%: 100%: 0%
Phenotype ratio – Wings: Wingless – 100%: 0% If a winged female mates with a wingless male, then 100% of the offspring will have wings. All of the offspring will have the genetic makeup, or genotype, of Ff. Since the dominant trait masks the recessive trait, all of the offspring will have the physical appearance, or phenotype, of wings (“Mendelian Genetics”).
F₂ Generation
Mrs. Cohen
Honors Biology
24 March 2013
Genetic Predictions in the Fruit Fly The Drosophila melanogaster is a fruit fly with a very short life cycle. They can be winged or wingless, and have red eyes or white eyes. The different options are called alleles. Alleles are the variants of a specific gene, and one is received from each parent on each chromosome. (“What Are Dominant and Recessive?”). It was chosen to use winged females and wingless males to predict the offspring in this experiment. The winged allele is dominant, meaning it only needs one allele to physically appear. The wingless allele is recessive, which gets covered up by the dominant allele (“Fruit Fly Genetics”). Each trait has two alleles in the flies’ genotype, or genetic makeup. In the parent generation (P), the flies used are homozygous, meaning they have two of the same alleles (“Mendelian Genetics”). The females are winged, and since that is a dominant allele, it is represented by a capital letter F. That means the female genotype is FF, because they get one allele from each parent. The males are wingless, which is a recessive allele represented by a lowercase f. Their genotype is ff. A Punnett square can be used to predict whether their offspring are winged or wingless. The offspring are called the first filial generation (F₁), while their offspring are called the second filial generation, or F₂.
F₁ Generation Punnett Square:
F F
f f
Genotype ratio – FF: Ff: ff – 0%: 100%: 0%
Phenotype ratio – Wings: Wingless – 100%: 0% If a winged female mates with a wingless male, then 100% of the offspring will have wings. All of the offspring will have the genetic makeup, or genotype, of Ff. Since the dominant trait masks the recessive trait, all of the offspring will have the physical appearance, or phenotype, of wings (“Mendelian Genetics”).
F₂ Generation
Cited: Biggs, Alton et.al. “Mendelian Genetics” Biology. 1st edition. New York: McGraw Hill, 2009. 277-282. Print. “Fruit Fly Genetics.” Basic Science Partnership. Harvard Medical School, nd. Web. 4 February 2014. “What Are Dominant and Recessive?” Learn. Genetics. University of Utah Health Sciences, 2014. Web. 4 February 2014.