Post on 19-Dec-2015
Fnord babies~ will be collected ~
In Fnords, orange (O) fur is dominant over blue fur (o). An orange fnord and a blue fnord mate, and produce
314 orange offspring and 307 blue offspring.
A. What is the genotype of the orange parent?
B. Two of the orange F1 fnords mate, and they produce both orange and blue offspring. If they have 98 blue babies in the F2 generation, about how many orange
ones are there?
C. Describe a cross you could make to figure out if one of the orange fnords from the F2 is homozygous
dominant or heterozygous.
Testcross
• A testcross is used to determine if an organism with a dominant phenotype is homozygous or heterozygous, by crossing it with a homozygous recessive individual
Codominance
For a trait that is codominant, both alleles affect the phenotype, and the result is offspring that have BOTH phenotypes.
Look at the example of horses
RR = Red fur
rr = White fur
Rr = Red AND White fur (roan)
Incomplete Dominance
RR RR’ R’R’
For a trait that shows incomplete dominance, one allele has an effect, and the other does not. If there are two copies, the
organism gets a “double dose” of the effect (red flower on left)
Flower Power
• If you crossed two of the pink flowers on the previous slide,– What % would be pink?– What % would be red?– What % would be white?
Are you color blind?
• 4 Sex-Linked Traits:
• 1. Normal Color Vision: A: 29, B: 45, C: --, D: 26
• 2. Red-Green Color-Blind: A: 70, B: --, C: 5, D: --
• 3. Red Color-blind: A: 70, B: --, C: 5, D: 6
• 4. Green Color-Blind: A: 70, B: --, C: 5, D: 2
Try One – on the back of your drill• A female with normal vision that has 1 copy of a
colorblindness gene (genotype X+ Xo) has children with a normal male (X+ Y).
A. What % of their male children will be colorblind?
B. What % of their female children will be colorblind?
C. Do all colorblind women have a colorblind father? Explain
Use Punnett squares to support each answer!