You perform a forward genetic screen to look for Arabidopsis thaliana mutants that are altered in cold stress responses. You find two mutants with opposite phenotypes. Mutant #1 is extremely resistant to cold stress (compared to the wild-type plant), and you identify the gene that has been mutated. It turns out that there is a single base pair mutation that changes a Lysine to an Arginine in the protein. Interestingly, this is the only lysine in this protein which contains 400 amino acids.
The other mutant is less tolerant to cold stress than a wild type plant. This mutant contains a different single base pair mutation in the same gene as mutant #1. This mutation changes a codon encoding Glycine that is 10 amino acids from the Nterminal end of the protein, to a Stop codon.Explain why these specific point mutations in the same gene can cause radically different mutant phenotypes. In your answer, please discuss the role this gene plays in the cold response.