Molecules of Life

Introduction - Common - Bacteria - Plantae - Chromista - Protozoa - Fungi - Animalia - References
Contents - Contact

These pages show a selection of the various organic compounds found in different living things. Here I have tried to arrange them not by chemical properties or uses, as seems to be most common, but by where they are found in the biological world. My hope is that this approach may help give some more perspective on the diversity of living things.

For sketching the compounds I’ve tried for something between 3-D models and the normal chemical notation. These are stylized ball-and-stick models with the general structure bent into the plane of the screen, and only individual atoms sticking up or down to reflect stereochemistry. Common atoms are marked according to the colour scheme shown here.

Usual # of bonds
4 3 2 1
H atom
1 Period
C atom
N atom
O atom
F atom
P atom
S atom
Cl atom
Br atom

Different groups have expanded along different lines. To someone interested in genetics all the main variety is among the prokaryotes, while to someone interested in structure or behaviour, there is little there compared to even small groups of animals. In many cases their evolutionary success is closely tied to key physical adaptations, like flight in insects and skeletons in vertebrates.

I think natural products provide another way of looking at this diversity that gives weight to both ends of this spectrum. In some groups success is closely tied to chemical adaptations, even when they are not unique, and many of the characteristics we care most about – colours, flavours, toxins, and practical uses – are dependent on them.

Just to have a place to start I have focused on covering pigments where known, and am slowly filling in others of interest. I am skipping proteins, which differ between each species and potentially individuals, unless they contain unusual building blocks. Even so there is an endless amount that could go here; please let me know if there is anything you would like to see.

Josh Grosse


  1. Common compounds
    1. Nucleotides
    2. Amino acids
    3. Tetrapyrroles
    4. Carotenoids
  2. Kingdom Bacteria
    1. Chloroflexi
    2. Cyanobacteria – blue-green algae
    3. Actinobacteria
    4. Endobacteria
    5. Proteobacteria – purple bacteria & allies
    6. Sphingobacteria
    7. Archaebacteria
  3. Kingdom Plantae
    1. Rhodophyta – red algae
    2. Chlorophyta – green algae
    3. Marchantiophyta – liverworts
    4. Bryophyta – mosses
    5. Tracheophyta – vascular plants
  4. Kingdom Chromista
    1. Cryptista
    2. Ciliophora – ciliates
    3. Miozoa
    4. Ochrophyta – heterokont algae
  5. Kingdom Protozoa
    1. Amoebozoa
  6. Kingdom Fungi
    1. Agaricomycetes
    2. Pezizomycetes
    3. Leotiomycetes
    4. Sordariomycetes
    5. Lecanoromycetes
    6. Eurotiomycetes
    7. Arthoniomycetes
  7. Kingdom Animalia
    1. Porifera – sponges
    2. Cnidaria
    3. Echinodermata
    4. Chordata – vertebrates & allies
    5. Annelida – segmented worms
    6. Mollusca
    7. Arthropoda – insects, crustaceans & allies
  8. References