A LITTLE LIGHTBULB MOMENT
Amino acids, proteins and enzymes
Amino acid backbone
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One carbon, one amino, one acid, one side chain
The idea behind the cue
All standard amino acids share the same alpha carbon attached to an amino group, a carboxyl group, a hydrogen, and a variable R group. The R group determines chemical behavior. Glycine is the exception because its R group is H, making it achiral.
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Short & simple
One carbon, one amino, one acid, one side chain
Acronym
AACHR — Airborne Avocados Chase Hungry Ravioli.
Story
A tiny chef stands on a central stool holding a backpack, a nose ring, a hydrogen pebble, and a sour lemon. The backpack changes from amino acid to amino acid, but the stool and the three fixed attachments stay the same.
Connect the pieces
- A (Airborne) → Alpha carbon: The shared central carbon in all standard amino acids.
- A (Avocados) → Amino group: This group is attached to the alpha carbon and is part of every standard amino acid.
- C (Chase) → Carboxyl group: This acidic group is also attached to the alpha carbon in every standard amino acid.
- H (Hungry) → Hydrogen: A hydrogen is attached to the alpha carbon as one of its four substituents.
- R (Ravioli) → R group: The side chain varies and determines chemical behavior; glycine is the exception because its R group is H, making it achiral.
- Airborne · Alpha carbon: The shared central carbon in all standard amino acids.
- Avocados · Amino group: This group is attached to the alpha carbon and is part of every standard amino acid.
- Chase · Carboxyl group: This acidic group is also attached to the alpha carbon in every standard amino acid.
- Hungry · Hydrogen: A hydrogen is attached to the alpha carbon as one of its four substituents.
- Ravioli · R group: The side chain varies and determines chemical behavior; glycine is the exception because its R group is H, making it achiral.
Know the limits
Applies to the 20 standard alpha-amino acids; glycine is achiral because its R group is H.
Further reading · OpenStax science textbooks ↗Check your understanding
Which feature is shared by all standard amino acids? A. A phosphate group attached to the alpha carbon B. An alpha carbon bonded to amino, carboxyl, hydrogen, and R groups C. A sulfur atom in the backbone of every amino acid D. A peptide bond connecting each amino acid before polymerization
A. A peptide bond connecting each amino acid before polymerization
B. A phosphate group attached to the alpha carbon
C. An alpha carbon bonded to amino, carboxyl, hydrogen, and R groups
D. A sulfur atom in the backbone of every amino acid
Reveal explanation
An alpha carbon bonded to amino, carboxyl, hydrogen, and R groups
Standard amino acids are built around an alpha carbon with four attachments: amino, carboxyl, hydrogen, and a variable side chain. Peptide bonds form only when amino acids link together.