Essential Numbers, Dates, and Comparisons
Key Numbers and Dates
| Data Point | Value |
|---|---|
| Estimated species on Earth | ~8.7 million |
| Year of Whittaker's Five Kingdom Classification | 1969 |
| Number of Whittaker's classification criteria | 5 |
| Year Ivanowsky discovered TMV (first virus) | 1892 |
| Year T.O. Diener discovered viroids | 1971 |
| Year Stanley Prusiner proposed prion hypothesis | 1982 |
| Prusiner Nobel Prize year | 1997 |
| Virus size range | 20–300 nm |
| Viroids compared to viruses | Smaller than viruses |
| Number of ascospores typically per ascus | 8 (after meiosis + one mitosis) |
Critical Structural Comparisons
| Feature | Gram-Positive | Gram-Negative |
|---|---|---|
| Peptidoglycan | Thick (multilayer) | Thin (single layer) |
| Outer LPS membrane | Absent | Present |
| Stain retained | Crystal violet (purple) | Safranin |
| Antibiotic sensitivity | Penicillin-sensitive | More resistant |
Cell Wall Material by Kingdom/Group
| Organism/Group | Cell Wall Material |
|---|---|
| Eubacteria | Peptidoglycan |
| Archaebacteria | Non-peptidoglycan polymers |
| Mycoplasma | No cell wall |
| Diatoms (Chrysophytes) | Silica () — frustules |
| Dinoflagellates | Cellulose plates |
| Euglena | No cell wall — pellicle (protein) |
| Fungi | Chitin |
| Plants | Cellulose |
| Animals | Absent |
Spore Type by Fungal Class
| Class | Sexual Spore | Structure | Asexual Spore |
|---|---|---|---|
| Phycomycetes | Zygospore | Free | Sporangiospore |
| Ascomycetes | Ascospore | In asci (sac) | Conidia |
| Basidiomycetes | Basidiospore | On basidia (club) | Rare |
| Deuteromycetes | None known | — | Conidia only |