Final answer:
To identify an amino acid given its structural formula at cellular pH, examine the side chain (R group) to determine if it's nonpolar, polar uncharged, negatively charged, or positively charged. The properties of the R group, such as ionization characteristics, determine the amino acid's role in protein structure and function. The amino acid's ability to act as an acid or base reflects its contribution to the overall behavior of proteins.
Step-by-step explanation:
To determine which type of amino acid is given by its structural formula at cellular pH, you can use three key criteria based on the properties of the side chain or R group attached to the alpha-carbon. These properties include the size, shape, solubility, and ionization characteristics, which greatly influence the overall structure and function of proteins. At neutral pH, amino acids have side chains that can be nonpolar, polar but uncharged, negatively charged, or positively charged.
The classification of amino acids into neutral, basic, or acidic depends on these side chain characteristics. Under cellular pH conditions, which is usually close to neutral (7.4), amino acids exhibit different charges based on their ionization states. A nonpolar R group generally means the amino acid does not ionize and remains uncharged, a polar uncharged R group retains no net charge but has polar characteristics, a negatively charged R group means the amino acid is acidic, and a positively charged R group indicates a basic amino acid.
To identify an amino acid, consider the structure of the R group at cellular pH by looking at its ability to donate or accept protons. This will determine if the amino acid behaves as a nonpolar, polar, acidic, or basic molecule. The structure of an amino acid at cellular pH will reflect its charge and its role in protein structure, determining if it contributes to hydrophobic, hydrophilic, or ionic interactions within a protein or peptide chain.