BIOLOGY 207 1st Edition Lecture 2 Outline of Previous Lecture I. Global Impact of MicrobesII. Importance of Historical Roots of MicrobiologyIII. Some Revolutionary Discoveries in Microbiology Outline of Current Lecture I. Impact of molecular phylogeny on biologyII. Eukarya, Archaea, BacteriaCurrent LecturePhylogeny of LifeI. Impact of molecular phylogeny on biologya. Phylogenetic diversity of microbesi. What is phylogeny? 1. The evolutionary history of a group of genes or organisms, inferred through shared characteristicsa. Eg. Dicots vs. monocots, vertebrates vs. invertebratesii. Important because of the ability to predicts and infer characteristics iii. Offers an evolutionary perspective because of the ability to see the shared characteristics and ancestry, how different traits change over timeb. It can be a challenge to measure the relatedness of microbesi. To create a phylogeny, rather than gauging physical characteristics, we take a gene sequence to compare (look at the DNA)ii. Molecular phylogenies can be created to measure how genetically close different organisms are1. Protein and gene sequences carry historical information and can be used to create these molecular phylogenies These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Gene in ancestral organismGene in organism A Gene inorganism B2. The length of the lines away from the gene in the ancestral organism represents its similarity to the original gene; the farther away it is, the more differences are present a. The arrows represent the different mutations that have occurred; in this case, the gene in organism B is more similar to the ancestral organismiii. Evolution of Genetic Code1. DNA---transcription---> RNA---translation; 3rRNAs---> Proteina. 3rRNAs: 1 in small subunit, 2 in large subunit b. the discovery that every organism shared some common ancestry/the molecular phylogeny of life was discovered in the 1970s by Carl Woese, who spent years building up the phylogeny 2. Using ribosomal RNA gene sequence allowed us to find the similarities between the genesa. Ribosome are present in all cells (not viruses)i. Cells need the ribosome to make proteinsb. They maintain similar functions between the different cellsc. Conserved and variable regions; they haven’t changed much as a result of evolution d. Adequate lengthe. Transferred verticallyi. Parent to offspring cell transfer, not horizontal transfer between members of different species3. The secondary structure of a 16s rRNA was discovered to have thesame stem in everything; below is a comparative analysis of SSU Secondary Structures in different organisms4. Primary sequence changes, which allows for variations in the species while the secondary structure (above) is preservedII. Eukarya, Archaea, Bacteriaa. A phylogenetic tree of all life reveals that there are 3 primary lines of evolutionary descenti. Microbes harbor the majority of the genetic diversity since they can be any of the three (eukarya, archaea, bacteria) ii. This provides the framework to explore microbial world b. Some of the commonalities and differences of the characteristics are shown belowc. Although both archaea and bacteria call under the category of being “prokaryotes”, some argue that we should differentiate the three kinds of life, not just separate in to prokaryotes vs. eukaryotesi. Comparisons of rRNA reveal domains of all three, rendering the term “prokaryote” obsoleted. Endosymbiotic origin of chloroplasts and mitochondriai. Suggests that the precursor to plant cells engulfed the organelles while they were still their own microorganismsii. Since they have their own genomes, including 16s rRNA, it strongly suggests that before it was its own microorganism, a eukaryote engulfed it and used it for its