Question

2. To understand the genetic basis of locomotion in the diploid nematode Caenorhabditis elegans, recessive mutations were obtained, all making the worm "twitch" ineffectually instead of moving with its usual smooth gliding motion. These mutations presumably affect the nervous or muscle systems. Twelve homozygous mutants were intercrossed, and the hybrids were examined to see if they twitched or not. The results were as follows, where "" means that the hybrid was wild type (gliding) and "t" means that the hybrid twitched: 1 4 5 6 8 10 12 1 6 10 12 Given that intercrossing mutant strains that all share a common recessive phenotype is the basis of the complementation test, what is the purpose behind the design of the complementation test? In other words, what is the test designed to identify? a. How many genes affecting movement have been identified from the above data? Which mutations are in which genes? Give the genes symbols of your choosing. b.

please show all work.

Answer 1

a) in a complementation test mutants which shows the same phenotype is crossed, this is to identify the number of genes involved to produce normal phenotype and the number of alleles of each gene.

b) if 2 mutants are can complement the phenotype that is the in the hybrid shows wildtype phenotype then the 2 mutations are in 2 different genes if 2 mutants cannot complement the phenotype means, 2 mutations are in the same gene, so the hybrid lacks one gene in the pathway.

so here

1,7-A

2,12-B

3,6-C

4,8,11-D

5,10-E

9-F

are different complementation groups, so there are 6 genes involved in the pathway, A, B, C, D, E, F.

and 1,7 are alleles of A

2,12 are alleles of B

3,6 are alleles of C

4,8,11 are alleles of D

5,10 are alleles of E

9 is the only allele of gene F