chapter one: the history of microbiology

Transcription

1 chapter one: the history of microbiology Revised 6/19/2018

2 microbes microscopic (small) organisms, viruses, prions prefix sci. notation frac. equivalent dec. equivalent kilo- (k) /1 = centi- (c) / milli- (m) / micro- (μ) / nano- (n) / pico- (p) /

3 scientific names Staphylococcus aureus and Escherichia coli can be part of the normal flora of the human body; S. aureus is found on the skin and E. coli in the large intestine.

4 microbes and human welfare UNIT ONE (chapters 1-9) microbes microbial metabolism microbial genetics & biotechnology gene therapy, rdna technology UNIT TWO (chapters 10-13, 27 & 28, presentations) microbial diversity & ecology biogeochemical cycling & bioremediation UNIT THREE (chapters 14-20) microbial diseases & immunology UNIT FOUR case studies of human disease

5 normal microbiota those present in & on the human body prevent growth of pathogens produce growth factors (folic acid & vitamin K) produce antimicrobial compounds pathogenic organisms human bacteria

6 chapter three, part I: microscopy & microscopy lab information

7 resolution resolution: the ability to distinguish two points shorter = greater resolution (electron > light) electron microscope light microscope unaided eye

8 Electron Microscopy Light Microscopy microscopy compared

9 INCREASING RESOLUTION microscopy

10 light microscopy simple vs. compound- # of lenses compound microscope- image magnified by objective & ocular lenses total magnification = objective lens ocular lens

11 FOV & DOV

12 measuring FOV ocular magnification objective magnification total magnification FOV (μm)

13 chapter one: the golden age of microbiology

14 the golden age of microbiology

15 biogenesis or spontaneous generation historical microbiology 1745: John Needham spontaneous generation

16 Chapter One Learning Objectives 1. What types of organisms are studied in microbiology? Which of these are considered non-living? 2. How are scientific names correctly written? 3. Six specific microbiological breakthroughs from the Golden Age of Microbiology were discussed in class. For each, you should commit to memory the sequence of events, researcher and contribution to the field of microbiology. 4. Discuss the four major experiments explained in class that led to the refutation of Spontaneous Generation and the acceptance of the theory of Biogenesis. For each leading up to the work of Louis Pasteur, why did the scientific community as a whole remain unconvinced of the Theory of Biogenesis. 5. Understand how microorganisms can play both a beneficial and a detrimental role in their interactions with people. Include normal flora in your discussion.

17 chapter four: the prokaryotic cell

18 why a cell wall prokaryotes are unicellular cannot regulate external environment live in extreme environments cell walls prevent osmotic lysis

19 morphology & arrangement

20 the prokaryotic cell: external structures glycocalyx: capsule or slime layer pili attachment prevent phagocytosis DNA transfer fimbriae attachment flagella motility

21 flagella Motility wet mount with Brownian movement Flagellar arrangement

22 Flagellar structure flagella

23 axial filaments/endoflagella: spirochetes anchored at one end; rotate to cause movement

24 (enteric peritrichous) taxis small size means they sense gradients temporally, not spatially attractants = tumble; run attractants = tumble (up gradient) repellants = tumble; run (move down gradient) Flagellar movement Motility

25 the cell wall prevents osmotic lysis; usually peptidoglycan Mycoplasmas: lack cell walls, sterols in plasma membrane Archaea: wall-less/pseudomurein (no NAM & D-amino acids)

26 Gram positive vs. Gram negative

27 acid-fast (AFB) cell walls waxy lipid (mycolic acid) bound to peptidoglycan Mycobacterium (Nocardia)

28 ester vs. ether linkages: the archaean cell membrane ester linkage ether linkage

29 metachromatic granules phosphate reserves energy reserves polysaccharide granules lipid inclusions sulfur granules carboxysomes CO 2 fixation gas vacuoles buoyancy magnetosomes iron oxide (destroys H 2 O 2 ) inclusions

30 hereditary information: the nucleoid region

31 8 10 hours, 113 genes 1. chromosome condensation 2. septum formation 3. forespore engulfed 4. peptidoglycan cortex formed 5. spore coat formed sporulation 6. resistance mechanisms develop, endospore released

32 the prokaryotic cell

33 Chapter Four Learning Objectives 1. Identify and correctly name the five morphological types, and arrangements of bacterial cells discussed in lecture. 2. Understand the location and function of each of the following prokaryotic structures: glycocalyx (capsule & slime layer), flagella, fimbriae, pili, cell wall, cell membrane, nucleoid region and inclusions. 3. Identify and correctly name the four flagellar arrangements. 4. Discuss the basic mechanism for bacterial motility. Include in your discussion how bacterial flagella differ from eukaryotic flagella in structure and movement and how different bacterial arrangements will affect how bacterial cells move. Include endoflagella/axial filaments in your discussion. 5. Discuss positive and negative chemotaxis and phototaxis. How do bacterial cells respond to attractants and repellants? 6. Why is the cell wall a necessary component of most bacterial cells? How is the cell wall of a bacterium different from plants, fungi, Archaea, and Mycoplasmas? 7. Understand the chemical make-up of Gram positive, Gram negative and Acid Fast cell walls. 8. What are the major structural differences between bacterial and archaeal cell membranes? 9. Provide the name and function of each of the bacterial inclusions discussed in lecture. 10. How does a nucleoid region differ from a nucleus? How is it similar? 11. Discuss the process of sporulation and germination. Why are spores useful? Can all bacteria produce spores?

34 chapter three and smear and staining labs information

35 light microscopy simple vs. compound- # of lenses compound microscope- image magnified by objective & ocular lenses total magnification = objective lens ocular lens

36 refraction & oil immersion

37 staining increases resolution stains increase visibility & emphasizes structures positive (basic) stains absorbed by cell chromophore is cation negative (acidic) stains repelled by cell chromophore is anion heat-fixed bacterial smears attach to slide & kill simple stain differential stains: distinguish Bacteria stain & counterstain

38 differential & special staining Differential Staining Gram stain Abx treatment, diagnosis, characterization Acid-Fast stain diagnosis: TB Spore stain food preservation & safety Special staining Capsule Pathogenesis STAINING

39 Chapter Three Learning Objectives 1. Define resolution. How does wavelength relate to resolving power? 2. Understand the mechanism by which light microscopes, scanning electron microscopes and transmission electron microscope allow you to visualize an image. Commit to memory the resolving power of each. 3. Explain the use of positive/basic stains and negative/acidic stains. How does each work and what part of the cell does each stain? 4. Define differential staining. For each technique discussed in class, understand the mechanism of action and what positive and negative look like.