Amino Acid Functional Groups: Matching quiz

Phenolic hydroxyl group (Phenol) attached to a phenyl ring

B. (Tyr)

Bicyclic indole ring system containing a heterocyclic nitrogen atom

H. (Trp)

Pure hydrocarbon benzene ring (completely hydrophobic and inert)

F. (Phe)

Highly reactive thiol / sulfhydryl group (-SH) capable of redox chemistry

J. (Cys)

Hydrophobic thioether group (-C-S-C-) packed between alkyl carbons

A. (Met)

Side chain carboxylic acid group (ionizes to R-COO⁻ at physiological pH)

G. (Asp / Glu

Aliphatic primary epsilon-amino group (-NH₃⁺) with a pKₐ of ~ 10.5

I. (Lys)

Highly basic, resonance-stabilized guanidino group (-NH-C(NH₂)=NH₂⁺)

C. (Arg)

Heterocyclic imidazole ring system with a pKₐ value near 6.0

E. (His)

Polar, uncharged carboxamide functional group (-CO-NH₂)

D. (Asn / Gln)