Question

Compare the structural formulas of the aromatic amino acids phenylalanine and tyrosine. Also compare the codons for these two amino acids.

Short answer

Answer: The main difference between the structural formulas of phenylalanine and tyrosine is their side chains. Phenylalanine has a phenyl group, while tyrosine has a phenol group with an additional hydroxyl group (-OH). In terms of codons, phenylalanine has two codons (UUU and UUC) with uracil (U) as their second base, while tyrosine has two codons (UAU and UAC) with adenine (A) as their second base.

Step-by-step solution

Phenylalanine structure

Phenylalanine is an essential aromatic amino acid with the formula C9H11NO2. Its structure can be described as follows: starting with a central carbon atom which is its alpha carbon (Cα), it is bound to an amino group (NH2), a carboxyl group (COOH), and a hydrogen atom. Its side chain is a phenyl group (-C6H5), which is an aromatic hydrocarbon, connected to the Cα. This phenyl group is responsible for the amino acid's aromatic property.

Tyrosine structure

Tyrosine is a non-essential aromatic amino acid with the formula C9H11NO3. Similar to phenylalanine, its structure begins with a central alpha carbon (Cα), which is bound to an amino group (NH2), a carboxyl group (COOH), and a hydrogen atom. Its side chain consists of a phenol group, which is a benzene ring (C6H4) with a hydroxyl group (-OH) attached to one of the carbon atoms. This phenol group provides the amino acid its aromatic property.

Compare the structural formulas

Comparing the structures of phenylalanine and tyrosine, we can see that the main difference is their side chains. While both have an aromatic ring, phenylalanine has a phenyl group while tyrosine has a phenol group with an additional hydroxyl group (-OH).

Phenylalanine codons

The genetic code specifies the amino acids in a protein through a series of three-nucleotide sequences called codons. Phenylalanine has two codons, which are UUU and UUC.

Tyrosine codons

Similarly, tyrosine also has two codons, which are UAU and UAC.

Compare the codons

Comparing the codons of phenylalanine and tyrosine, we can see that they differ in the second nucleotide base. Phenylalanine codons (UUU and UUC) have uracil (U) as their second base, while tyrosine codons (UAU and UAC) have adenine (A) as their second base. This difference in codons leads to the incorporation of different amino acids into a protein during translation.