Biological Diversity Bacteria Archaea Discover Biology 5 th

Biological Diversity, Bacteria, & Archaea Discover Biology, 5 th Edition. Anu Singh-Cundy & Michael Cain. Chapter 2: pp 24 -46.

Unity of Life • All life had common ancestor(s) • All living organisms have the same 4 nucleotides for DNA • Adenine = Thymine • Guanine = Cytosine • The same set of 3 nucleotides (codon) match the same amino acid • The Genetic Code (p 351) • All life on Earth can be categorized in 3 domains • Bacteria • Archaea • Eukarya

Evolutionary Divergence • 1 st proof of life = fossilized bacteria @ Gunflint Formation, Ontario • 2 x 109 years ago • Evolutionary Tree • Branching diagram • DNA • Physical features • Biochemical characteristics • Lineages = lines of descent • Node = Split into 2 separate lineages • Most recent common ancestor that BOTH lineages share • Clade = Branch • Given ancestor + all its descendents

Cladograms • Most recent common ancestor (MRCA) • At the node • Shared derived traits • Unique features originally in MRCA • Shared by all the descendants • Not seen in other branches • Implied time sequence • Timescale imprecise • Base represents the past • Leaves represent the present

Eukarya • All have membrane-bound organelles • Nucleus; mitochondrion; chloroplast; endoplasmic reticulum • Golgi apparatus • Four different kingdoms • • Protista – diverse collection: amoeba, paramecium, algae, diatoms, etc… Plantae – all plants Fungi – yeast, mushrooms, molds Animalia – all animals

Linnaean Hierarchy - Taxonomy • Devised by Carolus Linnaeus in the 1700 s • Domain – largest, most inclusive group of similar organisms (Taxon) • Kingdoms (6 taxa) • Phylum (pleural “phyla”) • Class • Order • Family • Genus (pleural “genera”) Scientific name = Genus species • Species (closest kin)

• Nonofficial classification • • • Prokaryotes 5 x 1030 on Earth Are unicellular; most microscopic but some can aggregate into mats Divide asexually by binary fission (1. 6 x 107 new E. coli per night) Have no membrane-bound organelles Nucleic acid is found in “nucleoid” region Have ribosomes on which to make proteins • Domains Archaea & Bacteria • Bacteria • Some cause disease; others are beneficial • Archaea • Evolved ~ 2. 7 x 109 yrs ago • Unique type of fat in plasma membrane • Many are extremophiles