Detailed Explanation
The variable chemical group attached to the central carbon (Cα) of each amino acid. The R group (also called the side chain) is what distinguishes one amino acid from another and determines its chemical properties: charge, size, hydrophobicity, hydrogen-bonding capacity, and reactivity.
The 20 standard amino acids are classified by their R groups: nonpolar/hydrophobic (Ala, Val, Leu, Ile, Pro, Phe, Trp, Met), polar/uncharged (Ser, Thr, Cys, Tyr, Asn, Gln), positively charged (Lys, Arg, His), and negatively charged (Asp, Glu). In a peptide chain, the R groups project outward from the backbone and determine the molecule's folding pattern, receptor binding, and biological activity.
Key Facts
- The variable chemical group attached to the central carbon (Cα) of each amino acid.
- The R group (also called the side chain) is what distinguishes one amino acid from another and determines its chemical properties: charge, size, hydrophobicity, hydrogen-bonding capacity, and reactivity.
- The 20 standard amino acids are classified by their R groups: nonpolar/hydrophobic (Ala, Val, Leu, Ile, Pro, Phe, Trp, Met), polar/uncharged (Ser, Thr, Cys, Tyr, Asn, Gln), positively charged (Lys, Arg, His), and negatively charged (Asp, Glu).
- In a peptide chain, the R groups project outward from the backbone and determine the molecule's folding pattern, receptor binding, and biological activity.
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