Amino Acids

Glycine is unique among amino acids as it has a hydrogen atom as its R-Group, making it the simplest in structure. Unlike other amino acids, it does not have a carbon chain or additional functional groups.

Glycine is unique because its alpha carbon is achiral, meaning it does not have a stereocenter and cannot exist in enantiomeric forms.

Alanine is a nonpolar, aliphatic amino acid with a simple methyl (-CH3) side chain, making it the second simplest amino acid after glycine.

Amino acids with aliphatic side chains have nonpolar properties and contain hydrocarbons. Valine, Leucine, Isoleucine, and Methionine fall into this category.

Valine is an essential amino acid with a side chain consisting of three carbon atoms, which is an isobutyl group. This side chain is what differentiates valine from other amino acids.

Isoleucine is an amino acid with a branched-chain structure. The correct R-Group is -CH(CH3)CH2CH3, which distinguishes it from other amino acids.

Methionine is an amino acid with a unique R-group of CH2CH2SCH3, making it distinct from the incorrect options provided.

Proline is a unique amino acid with a cyclic structure formed with a five-membered ring. The R-Group binds to the alpha carbon twice with different atoms, leading to its distinct shape and properties.

Phenylalanine has a benzene ring as the R-Group, which is -CH2-Phenyl. This is distinctive for phenylalanine, making the other options incorrect.

Tyrosine contains a phenol group (benzene ring with an -OH group attached) in its R-group, not an alcohol, carboxylic acid, or hydroxylamine group. This phenol group differentiates tyrosine from other amino acids.

Tryptophan is an amino acid with a specific structure including a 5-member ring and a benzene ring, along with other elements. The incorrect answers provide different structures that are not characteristic of Tryptophan.

Serine is an amino acid with a hydroxyl functional group attached to the carbon atom in its R-Group, denoted as -CH2OH.

In Threonine, the R-Group is -CH(OH)CH3, which consists of a carbon atom bonded to a hydroxyl group (-OH) and a methyl group (-CH3). This structure is specific to Threonine and distinguishes it from other amino acids.

Threonine is an amino acid with two chiral centers due to the presence of two stereocenters in its chemical structure. Chiral centers are carbon atoms bonded to four different groups, resulting in non-superimposable mirror images.

Aromatic side-chain amino acids contain a benzene ring in their structure, providing unique properties different from other amino acids.

Serine and Threonine are the only amino acids that contain aliphatic hydroxyl groups. Glutamine, Glycine, Cysteine, Tryptophan, Arginine, and Valine do not have aliphatic hydroxyl groups in their structures.

Asparagine and Glutamine have carboxamide groups in their side chains, making them polar amino acids. Alanine and Glycine are nonpolar amino acids, while Valine and Leucine are hydrophobic. Phenylalanine and Tryptophan are aromatic amino acids.

Asparagine is an amino acid with a side chain containing an amide group (-CONH2), giving it its characteristic structure.

In Glutamine, the R group is -CH2CH2CO(NH2), which differentiates it from the incorrect answers provided.

Basic amino acids are those with a positively charged side chain at physiologic pH, which allows them to act as bases by accepting protons. Lysine, Arginine, and Histidine are considered basic amino acids due to their chemical properties.

Lysine is an amino acid with a positively charged side chain at physiological pH, which is represented by the -CH2CH2CH2CH2NH3+ group.

Arginine is a basic amino acid with a guanidino group in its R group, giving it a positive charge at physiological pH. The correct structure includes the guanidino group (-CH2CH2CH2NHC(NH2)2 +) which is essential in the identification of Arginine.

Histidine is an amino acid with a unique structure containing a 5-membered ring in its R group. This distinguishes it from other amino acids and plays a significant role in its biochemical functions.

Amino acids with side-chain carboxylates have a carboxylic acid functional group in their side chain, making Aspartic Acid and Glutamic Acid the correct answers.

Aspartic acid is an amino acid, and its structure includes an R group of -CH2COO- which distinguishes it from other amino acids.

In Glutamic acid, the R group is -CH2CH2COO-. This indicates a side chain consisting of an ethyl group attached to a carboxyl group.

Cysteine is a sulfur-containing amino acid with an R-group of -CH2SH, which distinguishes it from other amino acids that may have different functional groups attached to the central carbon atom.

Alanine is commonly abbreviated as Ala (A) in biochemistry.