Final answer:
The offspring from the mating of a segregational petite mutant with a neutral petite mutant in yeast could display a variety of phenotypes determined by the inheritance and interaction of mitochondrial and nuclear DNA.
Step-by-step explanation:
When a segregational petite mutant (petite #1) mates with a neutral petite mutant (petite #3), the outcome depends on the specific inheritance patterns and interactions of the mitochondrial genomes from each type of yeast. In yeast, petite mutants are often characterized by defects in mitochondrial DNA which can affect the respiratory function. Segregational petites result from mutations in nuclear DNA that impact mitochondrial function, while neutral petites have mutations directly in the mitochondrial DNA. Without specifying the exact genetic mechanisms in this scenario, the general expectation is that offspring would exhibit a range of phenotypes depending on which type of mitochondrial DNA they inherit and how the nuclear DNA of petite #1 interacts with it.