Biochemistry

To classify amino acids into the categories of nonpolar, polar but neutral, acidic, or basic, we need to examine the properties of their side chains (R groups). The side chain determines the overall polarity and charge of the amino acid at physiological pH (approximately 7.4). Here's how we can classify each of the given amino acids: (a) **Arginine (Arg, R)** Arginine has a side chain that contains a guanidinium group. At physiological pH, this group is positively charged, making arginine a basic amino acid. (b) **Leucine (Leu, L)** Leucine has an aliphatic side chain that is hydrophobic and does not have any charge at physiological pH. Therefore, leucine is classified as a nonpolar amino acid. (c) **Glutamic acid (Glu, E)** Glutamic acid has a side chain with a carboxylic acid group. At physiological pH, this group is deprotonated, carrying a negative charge, which makes glutamic acid an acidic amino acid. (d) **Asparagine (Asn, N)** Asparagine has a side chain with an amide group. The amide group does not carry a charge at physiological pH and is polar due to the presence of a carbonyl and an amino group. Thus, asparagine is classified as a polar but neutral amino acid. (e) **Tyrosine (Tyr, Y)** Tyrosine has a phenolic side chain. The hydroxyl group can form hydrogen bonds, making the side chain polar. However, it does not carry a charge at physiological pH, so tyrosine is considered a polar but neutral amino acid. (f) **Phenylalanine (Phe, F)** Phenylalanine has a benzyl side chain, which is aromatic and hydrophobic. It does not have a charge at physiological pH, so phenylalanine is classified as a nonpolar amino acid. (g) **Glycine (Gly, G)** Glycine has a hydrogen atom as its side chain, which is neither polar nor charged. Therefore, glycine is classified as a nonpolar amino acid. In summary, the classification of the given amino acids is as follows: - Basic: Arginine (Arg, R) - Nonpolar: Leucine (Leu, L), Phenylalanine (Phe, F), Glycine (Gly, G) - Acidic: Glutamic acid (Glu, E) - Polar but neutral: Asparagine (Asn, N), Tyrosine (Tyr, Y)

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Classify the following amino acids as nonpolar, polar but neutral, acidic, or basic. (a) Arginine (b) Leucine (c) Glutamic acid (d) Asparagine (e) Tyrosine (f) Phenylalanine (g) Glycine

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