Biomolecules
What you're made of
You are a flexible bag of about 100,000 different molecules, but most of you boils down to four families: 20 amino acids (proteins), 4 nucleotides (DNA, RNA), a few sugars (glucose, glycogen), and lipids (membranes, hormones, fat storage). ATP runs the energy economy. NAD+ ferries electrons. Hemoglobin moves oxygen at 150 grams per liter of blood. This collection covers the biomolecules that biology runs on: the canonical 20 amino acids, the 4 DNA bases, the cofactors, the universal currencies. Read this section to start seeing yourself as a moving chemistry set.
Featured
Ascorbic acid (C)
The scurvy killer. James Lind ran one of the first controlled trials with lemon juice in 1747. Linus Pauling's megadose hypothesis has been repeatedly debunked — yet he still collected two Nobel Prizes.
Cholecalciferol (vitamin D3)
UVB photolyzes 7-dehydrocholesterol in your skin to make D3. Technically it's a hormone, not a vitamin — your body makes it. Deficiency links to rickets, osteoporosis, and autoimmune disease.
Cholesterol
It stiffens cell membranes and seeds every steroid hormone. Its 13-step biosynthesis collected 13 Nobel Prizes; the statin era of the 2000s rehabilitated its long-villainized reputation.
Folic acid (B9)
Prevents neural-tube defects in early pregnancy. After the US mandated folic-acid fortification of flour in 1998, spina bifida rates dropped 35% — a textbook public-health win.
NAD+
The cell's electron shuttle, central to glycolysis, the TCA cycle, and the electron transport chain. David Sinclair sells NMN/NR as an anti-aging fix; rigorous human data remains thin.
Stories in this theme
All 94 molecules in this theme
Ascorbic acid (C)
Antioxidant; collagen hydroxylation
Cholecalciferol (vitamin D3)
Bone mineralization hormone
Cholesterol
Membrane sterol; hormone precursor
Folic acid (B9)
One-carbon transfer; DNA synthesis
NAD+
Redox cofactor (e- acceptor)
cAMP
Second messenger
Creatine
Muscle energy buffer
Niacin (B3)
NAD/NADP precursor
Phylloquinone (K1)
Blood clotting carboxylase
Retinol (vitamin A)
Vision; epithelial differentiation
Thiamine (B1)
Thiamine pyrophosphate cofactor
Biotin (B7)
Carboxylase cofactor
Choline
ACh + phospholipid precursor
Menaquinone-4 (K2)
Bone + arterial K vitamer
Pyridoxine (B6)
PLP cofactor for transamination
Riboflavin (B2)
FAD/FMN precursor
α-Tocopherol (E)
Lipid-soluble antioxidant
Sphingosine
Sphingolipid backbone
2-Deoxy-D-ribose
DNA backbone
Adenine
DNA/RNA purine base; pairs with T/U
ADP
ATP-1 phosphate form
Alanine
Methyl side chain
AMP
Energy-low signaling nucleotide
Amylose (repeat unit)
Linear starch component
Arachidonic acid
C20:4 ω-6; prostaglandin precursor
Arginine
Most basic AA; NO precursor
Asparagine
Amide side chain; glycosylation site
Aspartic acid
Acidic AA
Butyric acid
C4:0; gut microbiome SCFA
Capric acid
C10:0 MCT
Caproic acid
C6:0; goat milk
Caprylic acid
C8:0 MCT; coconut
Cellobiose
Two glucose β-1,4; cellulose hydrolysis
Cysteine
Thiol; disulfide bond formation
Cytosine
DNA/RNA pyrimidine; pairs with G
D-Erythrose
Pentose phosphate pathway
D-Fructose
Fruit sugar; furanose form
D-Galactose
Milk sugar component; C4 epimer of glucose
D-Glucose
Primary blood sugar; pyranose form
D-Glyceraldehyde
Simplest aldose; chirality reference
D-Mannose
C2 epimer of glucose; UTI prophylaxis
D-Ribose
RNA backbone
D-Ribulose
Calvin cycle ketose
D-Threose
TNA backbone; primordial nucleic acid?
D-Xylose
Wood sugar; pentose
DHA
C22:6 ω-3; brain/retina
Dihydroxyacetone
Glycolysis triose; self-tanner
Elaidic acid (trans-oleic)
Trans-fat; cardiovascular risk
EPA
C20:5 ω-3; fish oil
Ergocalciferol (vitamin D2)
Plant-derived vitamin D
Erucic acid
C22:1; rapeseed oil
Glucuronic acid
Phase II detox conjugation
Glutamic acid
Acidic AA; MSG flavor
Glutamine
Amide side chain; N storage
Glycerol-3-phosphate
Triacylglycerol synthesis precursor
Guanine
DNA/RNA purine; pairs with C
Histidine
Imidazole side chain; enzyme catalysis
Hydroxyproline
Collagen-stabilizing modified AA
Hypoxanthine
tRNA inosine base; gout pathway
Isoleucine
BCAA; energy metabolism
L-Arabinose
Plant gum pentose
L-Fucose
Deoxysugar; blood group antigen
L-Rhamnose
Plant deoxysugar
Lactose
Milk sugar; galactose-glucose
Lauric acid
C12:0; coconut oil
Leucine
BCAA; mTOR activator
Linoleic acid
C18:2 ω-6; essential
Lysine
Basic AA; acetylation site
Maltose
Two glucose α-1,4; starch digestion product
Methionine
Start codon; methyl donor (SAM)
Myristic acid
C14:0; nutmeg
N-Acetylglucosamine (chitin unit)
Chitin/insect exoskeleton monomer
N-Acetylneuraminic acid
Cell surface; virus binding
Oleic acid
C18:1 ω-9; olive oil
Palmitic acid
C16:0 saturated; palm oil
Pantothenic acid (B5)
CoA precursor
Phenylalanine
Aromatic; tyrosine precursor
Proline
Cyclic; helix breaker
Raffinose
Trisaccharide; legume gas culprit
Retinal
Rhodopsin chromophore
Selenocysteine
21st AA; UGA recoded codon
Serine
Polar OH; catalytic triad
Stearic acid
C18:0 saturated; tallow
Sucrose
Table sugar; glucose-fructose disaccharide
Taurine
Sulfonic-acid analog; bile/energy drink
Threonine
Polar OH; phosphorylation site
Thymine
DNA pyrimidine; pairs with A
Trehalose
Stress-protective sugar
Tryptophan
Indole side chain; serotonin precursor
Tyrosine
Phenolic; thyroid/dopamine precursor
Uracil
RNA pyrimidine; pairs with A
Valine
Branched-chain essential AA
Xanthine
Purine catabolism intermediate
α-Linolenic acid (ALA)
C18:3 ω-3; flax seed