BIOLOGY 3 Lecture Notes - Lecture 28: Prokaryote, Saprotrophic Nutrition, Ribosomal Rna
Document Summary
Early biologists recognized two kingdoms: animals (kingdom animalia) and plants (kingdom plantae) the microscope revealed unicellular organisms; in the 1880s, ernst haeckel proposed the kingdom protista. Haeckel originally placed bacteria and cyanobacteria in monera since they lacked a nucleus in 1969, r. h. whittaker suggested a five kingdom system based on cell type, organization, and nutrition: Monera: prokaryotic bacteria that obtain organic molecules by absorption or photosynthesis. Protista: mainly unicellular eukaryotes that obtain organic molecules by absorption, ingestion, or photosynthesis; the classification of protists is debated. Animalia: multicellular eukaryotes, heterotrophic by ingestion, are generally motile. Fungi: multicellular eukaryotes, heterotrophic saprotrophs that form spores, lack flagella and have cell walls containing chitin. Generally, protists are considered to have evolved from monerans, and the fungi, plants, and animals evolved from protists via three separate lineages. Sequencing of rrna suggests all organisms evolved along three distinct lineages: domains bacteria, archaea, and eukarya.
