In 1981, a stray cat with unusual curled-back ears was adopted by a family in Lakewood, California. Hundreds of descendants of this cat have since been born, and cat fanciers hope to develop the "curl" cat into a show breed. The curl allele is apparently dominant and carried on an autosome. Suppose you owned the first curl cat and wanted to develop a true breeding variety. Describe tests that would determine whether the curl gene is dominant or recessive and whether it is autosomal or sex-linked.
The first thing to do is to breed the 'curl' cat to a wild-type cat (one with normal ears). Within their offspring there should be cats with normal ears and ones with curled ears. Now breed two 'curl' cat siblings together. If the trait is recessive you will only produce 'curl' cats. If the trait is dominant you will see a mixture of 'curl' cats and normal cats. Keep breeding curl cats in order to develop a line that is homozygous for the curl allele. Remember that inbreeding can cause deleterious effects.
If curl is a ...
Several paragraphs describing how to determine is a genetic trait is autosomal or recessive and dominant or recessive. Web references provided.