MIMM 211 Lecture Notes - Lecture 3: 16S Ribosomal Rna, Phylogenetic Tree, Symbiogenesis

• School: McGill University
• Department: Microbiology & Immunology
• Course: MIMM 211
• Professor: Benoit Cousineau

Document Summary

Taxonomy: artificial classification of organisms, solely based on visible similarities, still used to name organisms. Phylogeny: natural classification of organisms, reflects evolutionary relatedness between organisms. Before the concept of evolution, organisms were grouped based on morphological similarities, no relationship between the groups. Many fossils of animals and plants were found and used to suggest the appearance of different groops, built evolutionary family trees. Microorganisms were left out until late 60"s: no microbial fossils, very similar shaped. Use ubiquitous gene sequence to compare m-o and construct a universal phylogenetic tree of life. Tradition early schemes (before 1866: plants and animals. Ernest haeckel"s proposal (1866: plants, animals, microorganisms. Five-kingdom scheme of robert whittaker (1959: monera, protista, fungi, plantae and animalia. They used a molecular approach (16s ribosomal rna gene was found in every organism): bacteria, archaea and eucaryotes, these three groups are distant, length of branches depends on the distance between two species.