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Figure 1.2 Anton van Leeuwenhoek’s microscopic observations. Lens Location of specimen on pin Specimen-positioning screw Focusing control Stage-positioning screw Van Leeuwenhoek using his microscope Microscope replica From 1683 Drawings of bacteria Types of Microorganisms • • • • • • • Bacteria Archaea Fungi Protozoa Algae Viruses Multicellular animal parasites • Taxonomy = classification system • Linnaeus classification system based upon structural similarities between species. • Modern classification system based upon evolutionary relationships (determined by DNA sequencing). • Traditional (including lab manual for 101): Red, brown and green algae are in the Plant kingdom • Textbook for 101: Red, brown, and green algae are in the Protista kingdom • UC Berkeley: Red, brown and green algae are in separate kingdoms. (The Protista kingdom does not exist.) Classification categories • • • • • • • • domain – a group of related kingdoms kingdom - a group of related phyla phylum (plural = phyla) - a group of related classes. class - a group of related orders order - a group of related families family - a group of related genera genus (plural = genera) - a group of related species species - a kind of living organism . All organisms who can potentially reproduce together under natural conditions and produce fertile offspring. Most basic cell types: Prokaryotic: small, simple cells which lack a nucleus and other cell structures Eukaryotic cells contain a nucleus and internal structures 3 Domains 1. Bacteria (prokaryotic) – Includes blue-green algae 2. Archaea (prokaryotic) 3. Eukarya – The Eukarya are divided into more than 10 Kingdoms: Plants, Fungi, Animals and many others Figure 10.1 The Three-Domain System. Eukarya Bacteria Origin of chloroplasts Animals Fungi Origin of mitochondria Amebae Mitochondria Slime molds Cyanobacteria Proteobacteria Chloroplasts Archaea Methanogens Plants Extreme halophiles Ciliates Green algae Dinoflagellates Diatoms Hyperthermophiles Gram-positive bacteria Euglenozoa Giardia Thermotoga Horizontal gene transfer occurred within the community of early cells. Mitochondrion degenerates Nucleoplasm grows larger (DON’T NEED TO KNOW DETAILS) (DON’T NEED TO KNOW DETAILS) UC Berkeley Museum of Paleontology 2011: The 12 kingdoms of eukaryotes Bacteria (a domain) • Prokaryotes • Peptidoglycan cell walls • For energy, use organic chemicals or inorganic chemicals or photosynthesis (cyanobacteria = blue-green algae) Archaea (a domain) • Prokaryotic • Lack peptidoglycan • Some but not all live in extreme environments. These include methanogens, extreme halophiles, and extreme thermophiles Fungi (a kingdom) • • • • Eukaryotes Chitin cell walls Use organic chemicals for energy Most are multicellular (molds and mushrooms) but some are unicellular (yeasts) Protozoa (not a modern scientific category – includes multiple kingdoms) • Eukaryotes • Absorb or ingest organic chemicals • May be motile via pseudopods, cilia, or flagella Eukaryotic Algae (not a modern scientific category – includes multiple kingdoms) • • • • Eukaryotes Cellulose cell walls Use photosynthesis for energy Produce molecular oxygen and organic compounds Viruses • • • • • Acellular Consist of DNA or RNA core Core is surrounded by a protein coat Coat may be enclosed in a lipid envelope Are replicated only when they are in a living host cell Multicellular Animal Parasites • • • • Eukaryotes Multicellular animals Flatworms and roundworms Microscopic stages in life cycles Microbes in Our Lives • A few are pathogenic (disease-causing) • Decompose organic waste • Many are photosynthetic: produce organic molecules and oxygen, which are used by animals • Produce industrial chemicals such as ethanol, acetone and many others • Produce fermented foods such as cheese, bread, wine and vinegar Fermentation • Pasteur showed that microbes are responsible for fermentation • Some but not all fermentation converts sugar to alcohol • Microbial growth is also responsible for spoilage of food Normal Microbiota • Microbes normally present in and on the human body are called resident flora or normal microbiota • Normal microbiota help to prevent growth of pathogens • Normal microbiota produce growth factors, such as folic acid and vitamin K Figure 1.7 Several types of bacteria found as part of the normal microbiota on the surface of the human tongue. © 2013 Pearson Education, Inc. Naming Microorganisms • Linnaeus established the system of scientific nomenclature • Each organism is identified by two names: the genus and species Homo sapiens Canis familiaris Scientific Names • Are italicized or underlined – The first letter of the genus name is capitalized; the species name is not • Are “Latinized” and used worldwide • May be descriptive or honor a scientist Escherichia coli • Honors the discoverer, Theodor Escherich • Describes the bacterium’s habitat—the large intestine, or colon Staphylococcus aureus • Describes the clustered (staphylo-) spherical (cocci) cells • Describes the gold-colored (aureus) colonies Scientific Names • Scientific names may be abbreviated with the first letter of the genus and the species name: E. coli and S. aureus (DON’T NEED TO KNOW DETAILS) • Which is a correct scientific name? a. b. c. d. Baker’s yeast Saccharomyces cerevisiae Saccharomyces cerevisiae S. cerevisiae The Germ Theory of Disease • 1876: Robert Koch proved that a bacterium causes anthrax and provided the experimental steps, Koch’s postulates, to prove that a specific microbe causes a specific disease • An opportunist is a bacteria that does not normally cause a disease, but can become pathogenic under certain conditions, such as immunosuppression • Nosocomial infection: spread in a hospital or similar location