Fruit Flies Flashcards
Morgan discovered that the eye colour in Drosophila expressed what type of trait?
Sex-linked
(This supported Sutton and Boveri’s theory that genes are on chromosomes)
What characteristics make fruit flies excellent subjects?
1) they are easily bred in laboratory
2) they are prolific breeders
3) they have a relatively short life cycle (approximately two weeks), an the length can be manipulated by altering the incubation temperature
4) They have relatively prominent characteristics that can be used in sex determination
5)They have fairly simple chromosome organization of 3 pairs of autosomal chromosomes and 1 pair of sex chromosomes
What are the four major stages of a fruit fly’s life cycle?
1) Egg (fertilized egg or zygote)
2) Larva
3) Pupa
4) Adult
How long ones it take the adult female to be ready to mate with any available male?
Within eight to ten hours
How many pairs of chromosomes do Drosophila have and what type are they?
Four pairs of chromosomes
-three autosomes
-one sex cells
What are differences between males and females?
Size: males are usually smaller than females
Body colour: males have a caudal black ‘’cap’’ encircling their posterior abdomen; females tend to show
stripes which extend across the dorsal abdomen
Shape: Males have a more rounded caudal tip to the abdomen than females
Sex organs: on the ventral surface, only the males grow heavy dark bristles around their genital opening
Sex combs: males have black combs mounted on the anterior edge of the fourth segment of both of the male’s front legs
What does the chi square do?
It tests to see if the observed values are significantly different from what was expected
How to find the degree of freedom?
Number of phenotypes minus one
How to find critical x^2 value?
(Observed number - expected number)^2 / expected number
