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Polar Amino Acids quiz #1

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  • What structural features make polar amino acids hydrophilic, and which five amino acids are classified as polar?
    Polar amino acids are hydrophilic because their R groups contain electronegative atoms (such as oxygen, nitrogen, or sulfur) that can form hydrogen bonds with water. The five polar amino acids are serine (Ser), threonine (Thr), cysteine (Cys), asparagine (Asn), and glutamine (Gln).
  • Describe the unique functional groups present in the R groups of serine, threonine, cysteine, asparagine, and glutamine.
    Serine and threonine have alcohol (hydroxyl, –OH) groups; cysteine contains a thiol (–SH) group; asparagine has an amide group; and glutamine has an amide group with an additional methylene (–CH2–) group compared to asparagine.
  • What structural feature makes polar amino acids hydrophilic?
    Their R groups contain electronegative atoms (like oxygen, nitrogen, or sulfur) that can form hydrogen bonds with water.
  • Which five amino acids are classified as polar?
    Serine (Ser), threonine (Thr), cysteine (Cys), asparagine (Asn), and glutamine (Gln) are the five polar amino acids.
  • What functional group is present in the R groups of both serine and threonine?
    Both serine and threonine have alcohol (hydroxyl, –OH) groups in their R groups.
  • How does the structure of threonine differ from that of serine?
    Threonine is like serine but with an extra methyl group (–CH3) attached to its central carbon.
  • What unique functional group is found in the R group of cysteine?
    Cysteine contains a thiol (–SH) group in its R group.
  • What is the distinguishing feature of asparagine’s R group?
    Asparagine’s R group contains an amide group, which is a carbonyl (C=O) bonded to a nitrogen (NH2).
  • How does glutamine’s R group differ from that of asparagine?
    Glutamine’s R group has an amide group like asparagine, but with an additional methylene (–CH2–) group.
  • What mnemonic can help you remember the five polar amino acids?
    The mnemonic 'Santa’s Team Crafts New Quilts' helps recall Serine, Threonine, Cysteine, Asparagine, and Glutamine.
  • Which polar amino acid is capable of forming disulfide bonds, and what feature of its structure allows this?
    Cysteine is the polar amino acid capable of forming disulfide bonds. This ability comes from its thiol group (–SH) in the R group, which can form covalent disulfide bonds with another cysteine residue.