# What is a Building Block Word™?

In the spirit of the What is a Word™/Phrase™ series started by JLee, a special brand of Phrase™ and Word™ puzzles.

Hopefully, after the considerable amount of these types of puzzles on this website, you would know the drill :0

Still, if you want you can review the rules:

• Find out what characteristic a Building Block Word™ has.
• In addition, don't forget to justify why I call it a "Building Block Word™".

The list:

The CSV version:

Building Block Words™,Not Building Block Words™
PROTEST, RALLY
ILEUM, JEJUNUM
PHENOMENON, CIRCUMSTANCE
LEUKEMIA, MELANOMA
ALARMED, TERRIFIED
METRONOME, POLYRHYTHM
THRESHOLD, ACTIVATION
ASPIRATE, LABIALIZE
HISTORY, PREHISTORY
ARGUMENT, REBUTTAL
GLUE, TAPE
VALOR, BRAVERY
SERVICE, MEMBERSHIP


Hint 1:

Glycogen and cyst are Building Block Words™.

• (And yes, I have taken the Puzzling SE tour. Thanks for the invitations :D ) – oAlt Jul 31 at 8:20
• Welcome, and nice first puzzle :) For future reference, I provide and maintain a template for these types of puzzles that others are welcome to use. See e.g. What is a Useful Word™? - you can click edit, copy the markup, and paste it into your own question as a starting point. – Rubio Aug 2 at 2:59

## 1 Answer

Building Block Words™ are words ...

whose first three letters are an abbreviation for an amino acid, the building blocks of life.

Specifically:

Ala Alanine
Arg Arginine
Asn Asparagine
Asp Aspartic acid
Cys Cysteine
Gln Glutamine
Glu Glutamic acid
Gly Glycine
His Histidine
Ile Isoleucine
Leu Leucine
Lys Lysine
Met Methionine
Phe Phenylalanine
Pro Proline
Pyl Pyrrolysine
Ser Serine
Sec Selenocysteine
Thr Threonine
Trp Tryptophan
Tyr Tyrosine
Val Valine