Lecture 6 Microbes 3 Flashcards
Taxonomy is
The history of the tree of life: a classification scheme
Trees phylogeny is for
depiction of evolution. Introduced by Darwin, On the Origin of Species
Molecular phylogenetics result in (2)
new Domain of life, and extent of horizontal gene transfer
History of phylogenetics (3)
Watson & Crick: DNA double helix;
Crick: protein taxonomy;
Pauling & Zuckerkandl: molecular clock, taxonomy based on haemoglobin sequences
Principles of phylogeny
Distance-based: compute a distance matrix between each pair of sequences; join the most similar.
Parsimony: the one that minimizes the total number of mutations.
Molecular clock and its example
Tree for fast evolution like SARS-CoV-2 (point mutations every 2 weeks)
History of taxonomy of bacteria (notoriously hard to clarify): (4)
Linnaeus: chaos;
Haeckel: Monera at the tree base;
Chatton: pro/eukaryotes;
Woese: discovered Archaea.
Which sequence could be aligned and infer the position in the tree
Ribosomal RNA
Three domains of life are? Distinctness of Archaea.
Bacteria, Eukarya, Archaea.
Distinctness of Archaea: ether (-O-) in phospholipids instead of ester (-CO)
Not parimonious if separate Archaea (there will be reversion in the tree)
Difference betwen mono/para/polyphyly
Monophyly: group including all descendants of a common ancestor
Paraphyly: include some but not all descendants.
Polyphyly: not share a common ancestor.
Innovations of Eukarya compared to Archaea (3)
Multicellularity
Membrane bound nucleus and organelles
Mitosis (prokaryotes use binary fission)
What is syntrophy and how it proves the symbiosis of three domains
Cross-feeding; Co-culture of Archaea, Bacteria, and Eukarya
Models for origin of eukaryotes by endosymbiosis, three stages
Entangle-engulf-endogenize
What is LUCA
the Last Universal Common Ancestor. Branches to Archaea and Eubacteria.
