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.

Which is Haploid?Which is Diploid?

Haploid

Diploid

Which is Genotype?Which is Phenotype?

Phenotype

Genotype

bb

Which is Homozygous?Which is Heterozygous?

Heterozygous

Homozygous

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)

Codominance – Roan Horses

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?

Shh! Don’t say a word!

Write down what

numbers (if any) you can read in each

circle

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

There are a LOT more color blind men than women!

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!

Wrap up

• What you SHOULD HAVE learned:– testcross– Codominance– Incomplete Dominance– Sex-linked inheritance