Based on the information in the table, which of the following changes is least likely to produce a phenotypic
change in an organism?
A. GAU to GGU
B. GAU to GUU
C. GAU to GAA
D. GAU to GAC

GAU to GAC is least likely to change phenotype of an organism.

Phenotype of an organism is defined as the physical characteristics of an organism. This phenotype is dependent on the genotype of the organisms. This means the phenotypic characters are actually the expressions of the genes of the organisms. Now the genes are expressed in form of codons that are the three nitrogen base sequences. Each codon codes for a particular amino acid which in turn polymerises to from the protein which actually forms the phenotype of the organism.

Now there are 20 amino acids and 64 codons. Thus there are more than 1 codons for a single amino acid. So, if a codon is replaced by another codon which codes for same amino acid, then the phenotype is least likely to be affected.

Both the GAU and  GAC codes for aspartic acid. So the phenotype won't be affected much by this mutation

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