Devise an experiment to identify bacteria that are auxotrophic and unable to produce two amino acids, lysine (lys) and valine (val). The auxotrophic bacteria are in a pool of bacteria in which all the other bacteria are prototrophic. The genotype of the auxotrophs is lys⁻ val⁻. Describe each step in the experiment, identify the constituents in any growth medium or growth plates you propose, and identify the results that will conclusively identify bacteria that are lys⁻ val⁻.

Fifty bacterial colonies are on a complete-medium growth plate. The colonies are replica plated to a minimal-medium plate, and 46 colonies grow. What can you say about the bacteria from the four colonies that do not grow? Design an experiment and describe the methods you would use to determine if any of these four colonies are leu⁻, arg⁻, or val⁻.

Define the term genetic complementation.

Give another example of genetic complementation and describe how genetic complementation works in that case.

Look closely at the consolidated Hfr map and the data used to build the map on page 261. Suppose a fifth Hfr strain had the F factor inserted exactly halfway between cysE and leuU and had an orientation that was the same as that of Hfr 1. List the order of gene transfer for the first six genes transferred by this Hfr and the number of minutes of conjugation at which each gene is expected to be seen.

Define the term genetic complementation.

Describe how the term applies to an experiment in which two lysis-defective bacteriophages are able to coinfect a bacterial cell and produce lysis.