Classification of Amino Acids Flashcards

Classification of Amino Acids

• Amino acids are categorized based on the characteristics of their R groups.
• Despite diversity, amino acids share fundamental similarities.

Categories of Classification

• Grouped based on:
  • Charge (positive, negative, or neutral)
  • Hydrogen bonding ability (polar vs. non-polar)
  • Acidic versus Basic character

Non-Polar Amino Acids

• Hydrophobic; repel water.
• R groups primarily consist of:
  • Alkyl chains
  • Aromatic structures

Alkyl Side Chain Amino Acids

• Notable examples include:
  • Glycine: behaves like an alkyl group without having one.
  • Alanine: contains a methyl group (CH3).
  • Valine: characterized by branched alkyl structure (CH(CH3)4).
  • Proline: unique cyclic structure (C3H6).
  • Methionine: contains a sulfur atom (CH2CH2SCH3).
  • Isoleucine: branched alkyl chain (CH(CH3)CH2CH3).
  • Leucine: branched structure with isopropyl group (CH3CH(CH3)2).

Aromatic Side Chain Amino Acids

• Notable members:
  • Phenylalanine: features a benzyl group (CH2C6H5).
  • Tryptophan: includes an indole structure (CH2C8H5NH).

Polar Amino Acids

• Hydrophilic; attracted to water.
• R groups can classify into:
  • Neutral groups
  • Acidic groups
  • Basic groups

Neutral Side Chain Amino Acids

• Key examples include:
  • Serine: contains a hydroxyl group (CH2OH).
  • Threonine: has a branched hydroxyl structure (CH(OH)CH3).
  • Asparagine: features an amide group (CH2CONH2).
  • Glutamine: has an extended amide group (CH2CH2CONH2).
  • Cysteine: contains a thiol group (CH2SH).
  • Tyrosine: contains both hydroxyl and aromatic (CH2C6H4OH).

Acidic Side Chain Amino Acids

• Key members:
  • Aspartic Acid: features a carboxyl group (CH2COOH).
  • Glutamic Acid: has an extended carboxyl group (CH2CH2COOH).
• The carboxyl group acts as a strong hydrogen donor.
• Their conjugate bases are aspartate and glutamate upon proton donation.

Basic Side Chain Amino Acids

• Include:
  • Histidine: contains a nitrogen-rich structure (CH2C3H2N2H).
  • Lysine: long straight chain with an amino group (CH2(CH2)3NH2).
  • Arginine: characterized by multiple nitrogen atoms in its side chain (CCH2(CH2)3NHCNHNH2).
• Nitrogen atoms make these amino acids strong proton acceptors, giving them basic properties.

Explore the classification of amino acids through engaging flashcards. This quiz covers categories such as charge, hydrogen bonding capacity, and polar versus non-polar characteristics. Perfect for students looking to enhance their understanding of biochemistry!