Microbiology 2320 Spring 2017 Dr. Milind Suraokar CRN# 18168 PowerPoint Lecture Presentations prepared by Mindy Miller-Kittrell, North Carolina State University C H A P T E R 1 A Brief History of Microbiology What are microorganisms? Or Microbes? micro-scopic living organisms (entire) need a microscope to see them 1
Figure 3.4 Approximate size of various types of cells. ~10 um Red Blood Cells 1.5mm 1500 um Width of penny = 1500 Antoni van Leeuwenhoek 1674: First to see the microbial world 2
Lens Specimen holder Began making and using simple microscopes Often made a new microscope for each specimen Figure 1.2 Reproduction of Leeuwenhoek's microscope. http://physicsmuseum.uq.edu.au/van -leeuwenhoek-microscope-replica Figure 1.3 The microbial world. Leeuwenhoek observed a drop of pond water "animalcules = protozoa beasties = bacteria By end of 19th century, these organisms were called microorganisms and microbes Pond Scum Under the Microscope https://www.youtube.com/watch?v=0mfggbbxsf8 3
Real beasties The Early Years of Microbiology How Can Microbes Be Classified? Leeuwenhoek's microorganisms now grouped into six categories as follows: Bacteria Archaea Fungi Protozoa Algae Small multicellular animals There are 3 major types of living organisms One tree of life 3 domains Bacteria Archae Eukarya 4
2 µm 2 µm Figure 1.13 (a) Domain Bacteria (b) Domain Archaea (c) Domain Eukarya Kingdom Animalia 100 µm Kingdom Plantae Kingdom Fungi Animals: Protozoa Plants: Algae Fungi Protists All living organisms have cell(s) Some are unicellular others multicellular How many different types of cells There are only 2 types of cells Prokaryotic cells Eukaryotic cells Membrane around nucleus Membrane-bound organelles There are 3 major types of living organisms they all have cell(s) One tree of life 3 domains Bacteria prokaryotic Archae Eukarya eukaryotic 5
Figure 1.4 Eukaryotic cell Membrane Cytoplasm DNA (no nucleus) Membrane Prokaryotic cell Nucleus (membraneenclosed) Membraneenclosed organelles DNA (throughout nucleus) 1 µm Figure 1.4 Cells of the bacterium Streptococcus (dark blue) and two human cheek cells. Prokaryotic Nucleus of bacterial cells eukaryotic cheek cell Any of these 3 which is a microscopic organism is a microbe all One tree of life 3 domains all some Bacteria Archae Eukarya prokaryotic eukaryotic 6
prokaryotic cells vs eukaryotic cells differences and similiarities Use self-study guide to summarize So microbes can be prokaryotic or eukaryotic And they all have cell(s) But there are also microbes without cells bacteria Cellular and Acellular Acellular = viruses Characterisitics of cellular vs acellular microbes 7
Prokaryotic Microbes Bacteria and Archaea Unicellular and lack nuclei Much smaller than eukaryotes Most have cell walls but Bacterial cell walls contain peptidoglycan; Archaeal cell walls composed of polymers other than peptidoglycan Eukaryotic Microbes Protozoa (Animals) Single-celled eukaryotes Similar to animals in nutrient needs and cellular structure Live freely in water; some live in animal hosts Most are capable of locomotion by Pseudopods cell extensions that flow in direction of travel Cilia numerous short protrusions that propel organisms through environment Flagella extensions of a cell that are fewer, longer, and more whiplike than cilia Nucleus Pseudopods Cilia Flagellum Figure 1.6 Locomotive structures of protozoa. 8
Eukaryotic Microbes Algae (Plants) Unicellular or multicellular Photosynthetic Categorized on the basis of pigmentation and composition of cell wall Eukaryotic Microbes Fungi Eukaryotic (have membrane-bound nucleus) Obtain food from other organisms Possess cell walls Yeasts unicellular Molds multicellular grow as long filaments Figure 1.9 A colorized electron microscope image of viruses infecting a bacterium. Virus Viruses (acellular) Bacterium Viruses assembling inside cell 9
Figure 1.8 An immature stage of a parasitic worm in blood. Why Parasites? Red blood cell Immature stages are microscopic youtube-history-micro https://www.you tube.com/watch? v=zrirf5baat4&f eature=youtu.be The Golden Age of Microbiology Scientists searched for answers to four questions (late 1800 to 1900 - but long after Leeuwenhoek why?) 1) Is spontaneous generation of microbial life possible? 2) What causes fermentation? 3) What causes disease? 4) How can we prevent infection and disease? 10