Structure
Linear tetrapyrroles (called bilanes) include:
- Heme breakdown products (e.g., bilirubin)
- Phycobilins (found in cyanobacteria)
Cyclic tetrapyrroles, using four one-carbon bridges, include:
- Porphyrins, including heme, the core of hemoglobin
- Chlorins, including those at the core of chlorophyll.
- Corrins
Read more about this topic: Tetrapyrroles
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“Each structure and institution here was so primitive that you could at once refer it to its source; but our buildings commonly suggest neither their origin nor their purpose.”
—Henry David Thoreau (1817–1862)