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Slide 2 Microbilogy bacteria bacteriophage algae spirochaetes protozoaviruses cyanobacteria fungi Slide 3 Single-celled organisms and some non-cellular parasites What are microbes? Microbiology study of organisms too small to be seen by the naked eye Slide 4 Microorganisms (mos) are able to carry out life processes of growth, energy generation, and reproduction in a single cell. Mos are unicellular, small and reproduced by fission (asexually) 99% of the mos cannot be cultured in the lab Specifically, they have the ability to: grow on different substances withstand variation in temperature withstand variation in barometric pressure withstand osmotic pressure withstand changes in pH Slide 5 Microbial ubiquity MOs exist everywhere! They are in the soil, water, your skin and hair, your gastrointestinal tract, and even on or in your food. Yet we are barely aware that they exist. We become aware when we become sick, see spoiled food or damaged goods. However, the sheer minority (much less than 1%) cause disease. Most are beneficial to man and the biosphere of the earth. Slide 6 Theyre (almost) everywhere! An overview of prokaryotic life Prokaryotes were the earliest organisms on Earth (>3.5 bya) and evolved alone for 1.5 billion years. Today, prokaryotes still dominate the biosphere. Their collective biomass outweighs all eukaryotes combined by at least tenfold. More prokaryotes inhabit a handful of fertile soil or the mouth or skin of a human than the total number of people who have ever lived. Slide 7 Microbes exist in huge numbers! For example, for bacteria 10 times as many microbial cells as human cells on/in body 10 9 /gram of soil; 10 3 -10 4 different populations 10 11 / gram in intestinal tract 10 5 /ml in groundwater 10 4 /ml in ocean Slide 8 Amazing But True More bacteria in our bodies than human cells! More different types of bacterial genes in our body then there are human genes! The second human genome project (David Relman) Slide 9 What Microbiologists Do ??? Work in almost every industry - from food, agriculture and pollution control to biotechnology, pharmaceuticals and health, government agencies and labs, in education as teachers and researchers. No one microbiologist can study everything! That's why people who become microbiologists usually focus on a particular microbe or research area. Bacteriologists focus on bacteria. Virologists specialize in viruses. Mycologists study fungi. Epidemiologists track down outbreaks of disease Immunologists study how the body defends itself against microbial invaders? Slide 10 Fields of Microbiology Slide 11 10 Characteristics of Cells Eucaryotic cells: animals, plants, fungi, and protists contain double-membrane bound nucleus with DNA chromosomes contain membrane-bound organelles that compartmentalize the cytoplasm and perform specific functions Procaryotic cells: bacteria and archaea no nucleus or other membrane-bound organelles Slide 12 The size and cell type of microbes MicrobeApproximate range of sizes Cell type Viruses 0.01-0.25 m Acellular Bacteria 0.1-10 m Prokaryote Fungi 2 m->1m Eukaryote Protozoa 2-1000 m Eukaryote Algae 1 m-several meters Eukaryote Slide 13 Size of Microbes Microbes vary in size ranging from 10 nm (nanometers) to 100 mu (micrometers) to the macroscopic. Viruses in nm = 10 -9 m (meter) Bacteria in um = 10 -6 m Helminths in mm = 10 -3 m Slide 14 Relative sizes of microbes Slide 15 The power of microbe lies in its speedy growth Imagine the weight of biomass of E.coli after 24 hrs under optimal growth? Slide 16 Bacteria Reproduction Asexual, through binary fission No true sexual reproduction, since neither mitosis nor meiosis exist in prokaryotes Horizontal transfer of genetic material Transformation Transduction Conjugation Direct transfer of genetic material from one prokaryote to another Slide 17 B inary fission E. coli DNA cell wall Slide 18 Conjugation in E. coli Sex pilus Sex pilus connects cells and draws them together Conjugation tube then forms Slide 19 Kinds of microbes Non-cellular, parasitic molecules Viruses Viroids Prions Prokaryotes Domain Bacteria Domain Archaea Eukaryotes Several Kingdoms in Domain Eukarya Slide 20 Classification of Microbes Based primarily on genetic sequence data; e.g., small subunit ribosomal RNA present in all organisms NOTE: Microbes and Prokaryotes are not taxonomic categories Slide 21 Bacteria Prokaryotes Peptidoglycan cell walls Binary fission Ex: Escherichia coli Slide 22 Cyanobacteria Slide 23 Archaea Prokaryotes Lack peptidoglycan Live in extreme environments (extremophiles) Include: Methanogens Extreme halophiles Extreme thermophiles Slide 24 Archaebacteria Slide 25 Algae Eukaryotes Cellulose cell walls Photosynthetic Produce molecular oxygen and organic compounds Part of food chain Slide 26 Fungi Eukaryotes Chitin cell walls Molds and mushrooms are multicellular Yeasts are unicellular Slide 27 Protozoa Eukaryotes Mostly saprobes and commensals May be motile by means of pseudopod, cilia or flagella Slide 28 Viruses Acellular Obligate intracellular parasites Genome consist of DNA or RNA called Core Core surrounded by protein coat called Capsid Virion may be enclosed in lipid envelope Slide 29 Nonliving parasitic molecules Viruses Single or double stranded RNA or DNA with a protein coat Common cold, Ebola, HIV HIV Slide 30 Nonliving parasitic molecules Viruses Single or double stranded RNA or DNA with a protein coat Common cold, Ebola, HIV Viroids Short, single strand of RNA w/o protein coat Primarily infect plants Prions Protein particles w/o genetic material Kuru, mad cow, chronic wasting disease Slide 31 Differences between bacteria and viruses Viruses Obligate intracellular parasites No ribosomes DNA or RNA, not both seen by EM 10-100s of genes Tangled phylogeny Bacteria Usually free-living, but can be parasites Ribosomes DNA and RNA seen by LM 100s-1000s of genes Natural phylogeny Slide 32 Nutritional Patterns