Fruit Flies Full Lab Report

Abstract:

Drosophila flies is an insect that feeds on fruits, that's why it also called fruit

flies. Fruit flies have an important value in genetics studies and researches as it's a small animal,

with a short life cycle of just two weeks, easily cultured, and is cheap and easy to keep large

numbers. Fruit flies were helpful in improving many fields like biology, genetics and

immunology. In fact, studying the genetic inheritance of fruit flies had an important role

understanding genetic transmission mechanism in eukaryotes. Also, it had a significant role in

discovering that genes were related to protein synthesis. The mode of genetic inheritance for

these flies follow Mendel's principles.

Introduction:

The goal of this experiment is to determine the flies' phenotypic ratio and the type

of mutation. The mutation could be autosomal or sex-linked, and could be dominant or recessive.

In this experiment a wild type dark flies were crossed with mutant light body flies. As the body

color mutation is an autosomal linked mutation the results ratio should be 3:1 in the F1 and F2

generation. This ratio means that every three dark body color flies will offset one light body

color fly. The dark body allele is dominant over light body allele as proved by this experiment

and other experiments around the world. On the other hand, other mutations like the eye color

mutation will give different ratio. This difference occurs because the eye color trait is a sex

linked allele. Because it is a sex-linked mutation the ratio of crossing white eyed male with red

eyed female will be different than crossing red eyed male with white eyed female. The resulted

ratio for F1 generation in red eyed male with white eyed female cross should be 1:1. This ratio

indicates that every one red eye fly offset one white eye flies. While in the F2 generation the

ratio should be 1:1:1:1. On the other hand, if it is a cross between a white eyed male and red eyed

female, all the resulted flies in the F1 generation should have red eyes with 1:1 gender ratio.

While in F2 generation the ratio should be 1:2:1. This ratio indicates that all the resulted females

will have red eyes while half of the male will have red eyes and the other half will have white

eyes "1 red eye male: 2 red eye females: 1 white eye male ". The white eye mutation is a

recessive mutation.

Methods and materials:

Tow culture vials were prepared by adding one bucket of fly media in each plastic vial.

One bucket of distilled water was added to each plastic vial. The two media were mixed and left

to harden for one minute. A few grains of yeast were sprinkled on the surface of the media. The

two vials were plugged with pan. A wild-type and mutant flies were obtained. The flies were

anesthetized by Fly Nap. To anesthetize the flies the wand was dipped into the Fly Nap. The

bottom of the culture vile was tapped to knock the flies to the bottom of the vile. The plug was

pushed slightly to one side and the wand tip was stick below the plug. The vials were placed

horizontally until all the flies were anesthetized. The flies were spilled out the vials on a piece of

paper. The flies' phenotypes were observed. Four wild-type dark males and four mutant light

females were placed in the first vial. Four wild-type dark body, red eyes females and two dark

body, white eyes males were placed in the second vile. The vials were plugged and placed at a

specific place in the lab for several days. When the first generation flies start to emerge, the

parental flies were removed from the vials. The phenotypes for a hundred F1 generation flies

from each vial were observed. Four males and four females from each vile were placed in a new

two culture vials. The two vials were placed in a specific place in the lab for several days. When

the second generation flies start to emerge, the first generation flies were removed from the vials.

The phenotypes for a hundred F2 generation flies from each vial