Final answer:
Yes, treating a bacterial strain with chemical agents that cause A:T to G:C transitions can induce nonsense mutations. These mutations occur if a codon essential to gene function changes into a stop codon, thereby terminating translation prematurely. Transition mutations involve base substitutions and can lead to such changes if they occur at crucial gene locations.
Step-by-step explanation:
Is it possible to induce nonsense mutations by treating a wild-type bacterial strain with a chemical agent that causes A:T to G:C transitions in DNA? Yes, it is possible. A nonsense mutation is a type of mutation that turns a normal codon into a stop codon, terminating the translation process prematurely. This can occur through a base substitution mutation, where one base is incorrectly replaced by another during DNA replication.
Chemical mutagens, such as nitrous acid, can deaminate adenine to hypoxanthine, which base pairs with cytosine, changing an AT base pair to a CG base pair. Similarly, cytosine can be deaminated to uracil, which pairs with adenine, converting a CG pair to an AT pair. These types of mutations are called transitions, where a purine is replaced by another purine, or a pyrimidine by another pyrimidine.
Therefore, if the mutation induced by the chemical mutagen leads to the alteration of an essential codon to one of the three stop codons (UAG, UAA, or UGA), a nonsense mutation would be induced. So, while transitions commonly involve substituting one base pair for a similar base pair (purine for purine or pyrimidine for pyrimidine), they can result in creating a stop codon if they occur at a critical location within the gene sequence.