Sporopollenin vs Biogenic Silica
Definition
Pollen and spore walls are made of sporopollenin (a highly resistant biopolymer). Diatom frustules are made of biogenic opaline silica (SiO2·nH2O), a different chemistry entirely, but equally resistant to biological degradation and a key reason frustules persist in forensic samples.
- Pollen/spore wall
- Sporopollenin, a resistant biopolymer
- Diatom frustule
- Biogenic opaline silica
- Silica formula
- SiO2·nH2O
- Shared property
- Both highly resistant to biological degradation
Common questions
Why does this chemical difference matter for forensic recovery?+
Because the two materials survive different treatments, sporopollenin resists acid digestion used in pollen extraction, while silica frustules resist that too but dissolve in strong base, so a diatom search requires a different chemical protocol than a pollen search.
Can pollen and diatoms be recovered from the same sample using one method?+
Not with a single protocol. Standard practice runs separate preparations, an acid-based maceration for pollen and an oxidative digestion for diatoms, on split portions of the same sample.
Related terms
- Assemblage
- The full community of diatom taxa present in a sample. The relative frequencies and absolute counts of species in an assemblage reflect...
- Epitheca and Hypotheca
- The two halves of the frustule. The epitheca (larger) fits over the hypotheca (smaller) like a lid over a box. During cell...
- Frustule
- The silica cell wall of a diatom, composed of two overlapping valves (epitheca and hypotheca). Frustules are taxonomically distinctive, chemically resistant to...
- Raphe
- A longitudinal slit or canal in the valve of certain pennate diatoms that allows cytoplasmic streaming and active gliding movement across surfaces....
- Valve and Girdle Band
- The valve is the flat face of each frustule half, carrying the species-specific pore patterns used for identification. The girdle band is...