Lecture 16: Complementation, Dominance/Recessiveness, Homologous Recombination

Question 1

Basic procedure for mapping by conjugation or transduction

Answer 1

1. Insert DNA with selectable marker randomly into genome via transformation, conjugation, or transduction
2. Identify strains that have the selectable marker genetically linked to the phenotype-causing mutation
3. Then determine the DNA sequence of the region

Question 2

Genetic complementation

Answer 2

Process of identifying genes through reducing complexity of DNA to identify relevant genes or genomic fragments

Question 3

How to perform a complementation test

Answer 3

Must put two copies of the regions of DNA from different strains containing 2 different alleles into the same cell and see what effect this has on the phenotypes of the mutation.

Question 4

How do you get 2 copies of the same DNA in a bacterium

Answer 4

1. Transformation of DNA into the chromosome at a nonessential locus
2. Transformation or conjugation of self-replicating plasmids
3. Transduction using phages

Question 5

How to identify genes that complement a specific plasmid

Answer 5

-Make a library of plasmids containing fragments of the wild-type chromosome
-Transform the library into a single-mutant bacterium
-Plate on selective media to ensure each bacterial colony took up a plasmid
-Assay colonies for restoration of wild-type phenotype
-Isolate the plasmid and determine DNA sequence

Question 6

Merodiploid

Answer 6

An allele that is diploid for only that one gene