Final answer:
The presence of a 350 bp amplicon suggests that the lacz gene is disrupted in the DNA sample, likely due to the insertion of foreign DNA. The correct answer is option c.
Step-by-step explanation:
If a 350 bp amplicon were produced in a particular sample, one might conclude that the lacz gene has been disrupted by the insertion of foreign DNA. This inference is made based on the principle that the restriction site occurs only once in the middle of the lacz gene when using a cloning vector. The purpose of the lacZ gene within the plasmid is to encode the enzyme ß-galactosidase, which is involved in the breakdown of lactose into glucose and galactose. When a foreign DNA fragment is inserted into this restriction site, it disrupts the continuity of the lacZ gene, preventing the production of the functional enzyme and allowing for the identification of recombinant bacteria.
In the context of genetic cloning, bacteria that have taken up the recombinant plasmid will not produce the enzyme ß-galactosidase as a result of the disruption of the lacz gene. These bacteria will survive on plates containing the antibiotic ampicillin due to the resistance gene on the plasmid, but they will not trigger a color change in the substrate that indicates the enzyme's activity. This is a common technique used to identify successful recombinant cloning events in microbial genetics.
Therefore, the presence of a 350 bp amplicon, under these experimental conditions, can lead to the conclusion that candidate C) The lacz gene is mutated in the DNA sample is correct, since this size correlates with the insertion of foreign DNA within the lacZ gene in the plasmid used for transformation.