Worksheet 3-6:
Genetics Practice
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Supplemental Instruction
Iowa State University
Review:
Explain locus vs. gene vs. allele. Give an example.
Kelly
Biol 211 (4)
Holscher
10/28/15
Punnett Square practice:
1. Albinism (lack of skin pigmentation) is caused by a recessive autosomal allele. Persons who are
heterozygous for albinism are carriers. Persons who are homozygous recessive have the disease. If a
person who does not have the disease and is not a carrier marries a carrier for the disease, what is the
chance they will have a child with the disease? What is the chance they will have a child who is a carrier?
Show the Punnett square to support your answer.
What are the parental genotypes: Are they hetero/homozygous?
How many different gametes can each parent produce:
2. You have a dog that is homozygous recessive at locus (A) and has light fur. She has 8 puppies that all
express dark fur color. What is most likely the genotype of the father? Show the Punnett square to
support your answer.
What are the parental genotypes: Are they hetero/homozygous?
How many different gametes can each parent produce:
Linkage and Recombination Frequency:
Unlinked genes
Linked Genes
Why do we still see all the genotypes when genes are linked?
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When you count the F2 generation of a fly cross, you get: 85 brown winged flies 728 black
winged flies 712 brown wingless flies 75 black wingless flies What is the genetic distance
between the color and wing genes?
How does sex linkage differ from the linkage discussed above?
X-linked
Y-linked