Drosophila Melanogaster

A lab report on drosophila melanogaster, a species of fruit flies studied for their simplicity in biological terms.

Drosphilia Melanogaster, commonly referred to as a fruit fly, is a simple organism with a simple brain but highly developed nerves and muscles that is commonly used in biological research. Its lifespan is approximately 30 days long in its environmental 29°C. Development time (egg to an adult) is 7 days at a steady 28 °C, but time will increase in lower or higher temperatures (for instance, at 30°C, it took 11 days due to heat stress, and up to 50 days at 12°C). Females become receptive to courting males at 8-12 hours after emerging from the egg, whom in return perform five behavioral patterns in a sequence to court the females.

Telling apart the genders of fruit flies is quite simple. In males, look for a sex comb (an array of black bristles on the forelegs), a round abdomen, and five segments on the abdomen. For females, look for a pointed abdomen and seven segments on it.

So why are fruit flies widely used in studying genetics? They have a small size and have a large repructive cycle (females, which are easily cultured, can lay 500 eggs in 10 days), making them an ideal organism to test in the laboratory.

Careful observations of the results of genetic crosses allowed researches to establish that Drosphilia traits are carried on four chromosomes. The information on a chromosome pair can be transferred to another pair through a process called crossing over. The ability to manipulate genes in Drosphilia has allowed biologists to gain insight into how genes function in living organisms.

In this experiment, wild fruit flies (with wings) will be mated with an apterous one (without wings) to see if this has any effect on the passed down chromosomes. These traits are found within the second chromosome, and being apterous occurs due to a defect (caused by either biologists or nature) in the “apterous gene”.


1)For the F1 generation, 50% of the flies will be females and the other 50% will be males. In reproduction, there is a 50% chance that the sperm will join to create an X or a Y to go along with the X in the egg (XX=female, XY=male).

2)For the F1 generation, all of the flies should be wild even if one parent is apterous. They should be wild because the dominant trait (in this cross, it would be the ability to have wings) is the hereditary trait, and would mask over the other altered trait, allowing the F1 to have wings.

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12 Responses to “Drosophila Melanogaster”
  1. Jeff Says...

    On January 26, 2009 at 1:48 pm

    very resourceful

  2. Smith Says...

    On January 27, 2009 at 1:50 pm


  3. Bob Says...

    On January 28, 2009 at 12:01 pm


  4. t6j6y0 Says...

    On February 4, 2009 at 5:39 am


  5. asdf Says...

    On February 7, 2009 at 2:27 pm


  6. fdsa Says...

    On February 9, 2009 at 7:55 pm


  7. asdf Says...

    On February 25, 2009 at 8:16 pm


  8. fdsa Says...

    On March 23, 2009 at 3:29 pm


  9. asdf Says...

    On March 30, 2009 at 5:56 pm


  10. Emu Says...

    On November 1, 2009 at 5:17 pm


  11. Emu Says...

    On March 21, 2010 at 9:55 am


  12. shishkani Says...

    On May 18, 2010 at 5:40 pm

    Wow, this is a badly written experiment. Its only point is to examine heredity of a recessive trait, and it doesn’t even do a good job of explaining that.

    While normal male fruit flies do have an x and a y for their first chromosome, and normal females have two x’s, fruit flies’ sex is not determined the same way a human’s is – in other words, it is not a matter of whether the fly is xx or xy. It’s actually the ratio of sex chromosomes to other chromosomes.

    If a fly has one x, and two copies of all the other chromosomes, he will develop as a normal male. If a fly has two x’s, and two copies of all the other chromosomes, it will become a female. However, if the fly had two x’s and four copies of all the other chromosomes, it would become a male.

    A second issue with this is about the ratios of offspring. It is not enough to say that ‘a few’ will come out showing the apterous- phenotype in F2. In fact, about 1/4 of them should be missing their wings, the other 3/4 will have wings. Why it falls out this way is an integral part of this experiment, and really should be explained in more detail if students are going to learn anything.

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