Genetics Chapter 7: Mutations and Gene Structure

Complementation Testing and Gene Structure

• Complementation testing is a method used to determine whether two mutations are in a single gene or in different genes.
• The results of complementation testing reveal whether different mutations are alleles of the same gene or mutations in different genes.

Complementation Table for X-Linked Eye Color Mutations in Drosophila

• The table shows five complementation groups (genes) for X-linked eye color mutations in Drosophila.
• Mutations in white, cherry, coral, apricot, and buff are alleles of the same gene - white (w).
• Mutations in garnet, ruby, vermillion, and carnation are alleles of different genes.

Gene Structure and Mutations

• A gene can accommodate different mutations, which can alter phenotype in different ways.
• Each mutation may change only a specific part of a gene, while other mutations alter other parts.
• The structure of a gene allows for intragenic recombination, where recombination can take place between different mutations in the same gene.

Benzer's Experiment with Phage T4

• Seymour Benzer used phage T4 to study intragenic recombination in the rII region.
• Phage T4 is a virus that infects E. coli and has advantages for detecting intragenic recombination.
• Benzer's experimental results revealed that the rII region in bacteriophage T4 contains two genes, each composed of many nucleotide pairs.
• Benzer used deletions to map mutations in the rII region.

This quiz covers the concepts of complementation testing, gene structure, and mutation mapping, including Benzer's experiments on the rII region in bacteriophage T4 and Drosophila eye color mutations.