Microorganism Organization, Structure, and Function PDF

History/Classification of Microorganisms Phylogenetic trees: – Relate microorganisms together in terms of evolution. – It is the evolutionary relationship between organisms.  History/Classification of Microorganisms The first phylogenetic tree was comprised of only two kingdoms:...

History/Classification of Microorganisms Phylogenetic trees: – Relate microorganisms together in terms of evolution. – It is the evolutionary relationship between organisms.  History/Classification of Microorganisms The first phylogenetic tree was comprised of only two kingdoms: animals and plants. Unicellular organisms e.g. Euglena and Volvox (protozoans) have both animals and plant characteristics: – They are motile and have flagella (animal-like). – They can photosynthesize (plant-like). Where should they be classified?  History/Classification of Microorganisms A new classification which includes all living things was developed: prokaryotes and eukaryotes. The differences between the two groups include: – Presence of nucleus. – Presence of membrane-bound organelles. – Eukaryotes (10-20 µm) are larger than prokaryotes (1-5 µm). Note: some prokaryotes have membrane-like structures.  History/Classification of Microorganisms In 1960, Robert Whittaker developed the five kingdom classification which is still widely used today: – Monera (Eubacteria and Archaea) – all are prokaryotes – Protists – Fungi – Plants – Animals He based the classification on various characteristics including nutrition mode, motility, size, etc.  History/Classification of Microorganisms Relatively recently, Carl Woese set a new classification system based on the analysis of rRNA, which includes three domains: – Bacteria – prokaryotes – Archaea – prokaryotes – Eukarya: Animals Plants Protists Fungi  History/Classification of Microorganisms Archaea vs. Bacteria: 1. Different rRNA. 2. Chromosome(s): Bacteria: single or few; circular. Archaea: single; circular. Eukarya: several; linear. 3. No peptidoglycan cell walls in Archaea. 4. Different surface lipids: Bacteria: – fatty acids with ester linkages. – CM may contain sterols e.g. Mycoplasma Archaea: – long-chain branched hydrocarbons with ether linkages. – CM has no sterols. 5. Archaea live in harsh conditions (some are methanogens).  Categories of Classification Eight major taxa called the hierarchical system: – Domain (superkingdom) – Kingdom – Phylum (division) – Class – Order – Family – Genus – Species Some taxa are nonmandatory e.g. subkingdom, superclass i.e. not all organisms have to have them. In bacteria and archaea there is no such thing as subspecies. It’s called “isolate” or “strain” instead.  Bacterial Cell Sizes/Shapes Prokaryotic cell size: – Common bacterial size is 1-5 or 1-10. – Rods are usually 1x2 µm (width x length). Some bacteria may have the diameter of 0.1 µm. Bacilli size ranges from 0.5-4 µm wide, to up to 15 µm long (