The Expression of Genes by Pea Plants - Lab Report Example

The life cycles could also be changed depending on the environment or specific mutations of genetics. At room temperature, the flies may take 10 days from egg to adult. This makes the fruit fly to be the best subject for research on genetics since multiple generations could be studied for a short duration of time. The fruit fly life cycle begins whenever an egg is laid by a female that is impregnated. The fly only gives out one egg at a moment. The hatching of the egg occurs within 22 hours, and the larvae mature in four days (Manning 8). After this, the larvae would follow three stages up to the pupa stage. In this stage, the pupal case is established, hardens, and darkens in a duration of 4 to 6 days. Lastly, the pupa changes to the adult stage. The male fruit flies have a body that is small with a black tip on their body end. The female fruit fly does have an abdomen that is pointed and light compared to males. The prime objective of the experiment involves the performance of a dihybrid cross.

Flies that were hybrid for two traits (dumpy wings or normal wings, black or normal body) together with two different eye colors (wild red type and sepia brown) were provided for the experiment. The two were produced through the crossing of homozygous sepia-eyed flies, normal-winged, red-eyed flies, and dumpy. Prior studies have shown that dumpy wing mutation is an x-linked trait that is recessive and thus carried by the x chromosome that determines the sex. Through a Punnett square for the initial generation, the genotype that is expected and the ratio phenotype could be found. This is displayed in Table 1.

XdwXdw = Dumpy wings female

XbY =black body male

TABLE 1: Punnett square for the generation of dumpy wing males and black body males.

Dumpy wing

Xdw

Dumpy wing

Xdw

Black body

Xb

XdwXb

XdwXb

Black Eye

Y

XdwY

XdwY

According to Table, 1, it is certain that the phenotype ratio of the first generation is a dumpy wing, half male, half female. This information can be used to generate a second Punnett square. Since the female may contain the same genotype, the males may carry the same genotype and one punnet square would be created since there fails to be variance in the flies. For the second trait, the punnet square would be given in Table 2.

XwrXwr = wild red type female

X sbY = sepia brown male

TABLE 1: Punnett square for the generation of dumpy wing males and black body males.

Wild red type

X

Wild red type

X

Sepia brown type

Xsb

XwrX sb

XwrXsb

Sepia brown type

Y

XwrY

XwrY

According to Table, 2, it is certain that the phenotype ratio of the first generation is white-red type, half male, half female.