In 1981, a stray black cat with unusual rounded
curled-back ears was adopted by a family in California. Hundreds of
descendants of the cat have since been born, and cat fanciers hope to
develop the "curl" cat into a show breed. Suppose you owned the
first curl cat and wanted to develop a true breeding variety.
How would you determine whether the curl allele is
dominant or recessive?
Mate the stray to a
non-curl cat. If any offspring have the "curl" trait it is likely
to be dominant. If the mutation is recessive, then on ly non-curl
offspring will result.
How would you select for true-breeding cats?
You know that cats are
true-breeding when curl crossed with curl matings produce only
How would you know they are
A pure-bred "curl cat" is
- If the trait is recessive any
inividual with the "curl" condition is homozygous
- If the trait is dominant you
can determine if the individual in question is true breeding (CC)
or heterozygous (Cc) with a test cross (to a homozygous recessive