AP Biology Discussion Notes
Tuesday 04/07/2015
Goals for the day
• Be able to use a chi square analysis to analyze
whether actual data is close to our predictions
(within the probability that we expect)
• Be able to say WHY crosses might not have given
us the ratio we expected.
• Be able to predict the probability of an event
(getting particular offspring or getting a particular
gamete)
Question of the day 4/07
• How many gametes would you expect from a FLY
who was homozygous for 3 different traits?
• How many would you expect for a fly that was
heterozygous for the same 3 traits?
If you did a Punnett square to show the possible offspring
of a cross between these flies, how many boxes should
you make?
Fly Lab Challenge Sheets
Fly Lab Challenge Sheets
• Which groups were “OVER – represented” and
how did these compare to the parental
genotypes/phenotypes?
Assumptions & Evidence
Assumptions:
– Wild type (+) – Assume dominance
– ordered flies are Purebred
– Traits are Autosomal
– Basic & Complete Dominance
– All traits are Non-lethal
– Mendel’s Laws are at work
• Law of segregation
• Law of independent assortment
Linked Genes
• Genes close together on the SAME
chromosome so that crossing over doesn’t
happen frequently between them.
• Breaking the law of independent assortment.
• The Alleles for one trait segregate (separate)
independently of the alleles for other traits
Fly lab
Assumptions:
– Wild type (+) – Assume dominance
– ordered flies are Purebred
– Traits are Autosomal
– Basic & Complete Dominance
– All traits are Non-lethal
– Mendel’s Laws are at work
• Law of segregation
• Law of independent assortment