This Punnet square shows to possible combinations of genes in the children of parents that both have the genotype "Ee".
Click on image for full size
Windows to the Universe original image
Answers to the Genetic Puzzle!
- Mary must have two recessive genes to have attached earlobes, so her genotype
- If Mary inherited a recessive gene from each parents, then both of her parents
must have the recessive gene “e” in their genotypes. However,
if both of them have free hanging lobes, then they must also have the dominant
gene “E”. So, both parents must have the genotype “Ee”
- If Fred also has free hanging lobes, the dominant trait, then at least one
of his genes must be dominant (“E”). Did you figure out the possibilities
for the other gene based on the parents’ genotypes? The picture at the
left shows what the Punnet Square looks like.
With two parents that have the genotype Ee, there are three possible outcomes
for the genotypes of the children.
- One out of four (or 25%) will likely have the genotype “ee”
- Two out of four (or 50%) will likely have the genotype “Ee”
(free hanging lobes)
- One out of four (25% will likely have the genotype “EE” (also
free hanging lobes)
So, Fred could have a genotype of “Ee” or “EE”!
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