Lab 3: Drosophila Genetics Flashcards
Why are drosophila used to study genetics?
1) Produce lots of progeny in small amount of time
2) Short 2-week lifecycle
3) easily-recognizable mutant forms
4) Easily maintained, breeds in lab on a simple carbohydrate-yeast source
Define true breeding
a homozygous individual that will only give copies of genes for their own phenotype. If allowed to reproduce, they would produce progeny that have the same characteristics
In this experiment, which eye color was wild type? mutant?
Red eye= wild type
Sepia= mutant autosomal recessive
White= mutant sex linked recessive
How could you differentiate between males and females?
Males have a larger black part at the end of their abdomen, the also have sex combs on two of their limbs
Females have a longer pointed abdomen with several stripes and an ovipositor. They do not have sex combs
How do you immobilize drosophila?
flies become immobile when exposed to low temps, analysis can be conducted when flies are placed on top of an ice and water slurry in a petridish because it creates a HEAT SINK
Why do you add ice and water? why not just ice?
you add water to increase the surface area of the heat sink and to avoid any hot pockets where the flies may warm up and remobilize.
Why does this experiment call for virgin female flies?
Female drosophila can store sperm and use it for the rest of their reproductive lives. In order for us to ensure she has mated with the appropriate male and is not using some other flies sperm to produce our F1 generation, we need the females to be virgins.
How are virgin females obtained?
stock of true breeding fly vials were cleared of all flies, and only flies that emerge from the pupae in the following 6 hours are used to initiate this experiments cross.
Define reciprocal cross
A pair of crosses between a male with one trait and a female of another trait (probs wild type) and vise versa.
Why did we preform a reciprocal cross?
doing a reciprocal cross allows us to determine if a trait is sex linked, if different ratios occur of the F2 depending on which parent is mutant, it may indicate that the trait is not a typical autosomal trait.
Name some sources of error that happened in this lab
dead parent flies, wrong mates, infection, wrong sexes, females mature faster than males, skewing the end progeny fly count.
Why must P1 flies be removed after they produce progeny?
to prevent parental male flies from inseminating the newly hatched female flies. Because females can store sperm, F1 females would not be able to mate with F1 males if they have been previously inseminated.
