Question

Starting with a population of genetically identical dragonflies, you discover two new mutant lines that are wingless. In both lines, the wingless phenotype is inherited in a autosomal recessive pattern. You cross a wingless dragonfly from one mutant line to a wingless dragonfly from the other line. All the offspring from this cross (line 1 X line 2) have wings, therefore you conclude the mutation that caused the wingless phenotype in the lines:

Select one: a. Was in two different genes. b. Was in the same DNA base position within the same gene. c. Was within the same gene, but not necessarily the same DNA base position.

Answer 1

The wingless phenotype is inherited autosomal recessive mutation means that dragonflies will have a wingless phenotype only if the mutant allele is in homozygous condition. The cross between homozygous dragonfly gives progenies having wings (wild-type).

The mutation that causes the wingless phenotype in the lines was in two different genes is the correct answer because if the mutation was in the alleles of the same gene the progenies produced from the cross should be wingless which is not the case. The wingless phenotype is the result of recessive mutation which means neither of the parents has a wild-type allele. The mutation is in the two different genes which may be involved in the development of wing formation in dragonfly. Therefore option A is correct.

The mutation was in the same base position within the same gene (b) and was within the same gene but not necessarily the same DNA base position is not the right answer because if this is the case progeny should have a wingless phenotype.