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Lecture

Microbes Lecture Notes.docx

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Department
Biology
Course
BI276
Professor
Joel Weadge
Semester
Fall

Description
Microbes- Chapter 1 and 2 9/10/2012 10:27:00 AM Midterm Oct 17 th History of Microbes Robert Hooke Cell theory- basically through a small microscope he created, he would see the smallest forms of life (down to 10um) Antoni van Leeuwenhoek Father of microbiology first to discover bacteria with his microscope Under a drop of water he saw tiny organisms (bacteria) Edward Jenner Father of immunology – discovered vaccine to smallpox in 1798 first time a disease was cured before it occurred Louis Pasteur Process Fermentation with beer and wine Vaccines – anthrax (rod-shaped bacteria), fowl cholera, rabies (virus) Created the process of heat sterilization for spoiled beer (which was basically spontaneous generation or tiny organisms/microbes) ** refer to lecture notes for images of process Ignaz Semmelweis led to germ theory Robert Koch link between microbes and disease (Germ theory) Causative agents of anthrax and tuberculosis improved pure culture Postulates: 1. The suspected pathogen must be present in all cases of the disease and absent from the healthy animal. However there are exceptions because stuff like STD’s do not grow outside of humans 2. the suspected pathogen must grow in pure culture 3. cells from Martinus Beijerinick metabolic diversity described the first virus (TMV) beginnings of virology (first one to isolate a virus by a series of filtration) Sergei Winogradsky nutrient cycling – nitrogen/sulfur chemolithotrophs – don’t use carbon sources microbial communities Modern Microbiology Applications 1. Agriculture 2. Environmental 3. Industrial 4. Medical Writing scientific names: 1.Italicied/ underlined 2.Genus is catialized 3. Species is lower case Similarities between eukaryote (fungi, protozoa, algae) and prokaryotes (bacteria, archaea) Similar function, ribosomes, DNA, plasma membrane, cytoplasm Differences: Size, lack of some organelles, cell walls Viruses -viruses are not a cell, debatable whether they are alive, because they need a host to survive off of, but are considered prokaryotes - 1000 times smaller than bacteria cell and thus they cannot have enough makeup to survive on their own -they also lack a cell wall - there are some viruses that are harmful to bacteria but are not to humans spirulina species – non-pathogenic bacteria that can actually be eaten to fulfill supplements in the body Fungi – unicellular: yeasts; multicellular: molds Protozoa – unicellular, free living or parasitic Algae – unicellular forms, photosynthetic eukaryotes Lichens – looks like moss - have hard time producing energy however have the utensils of photosynthesis - two forms of symbiosis: o fungus + algae o fungus + bacteria Later Scientists Carl Woese First to define archaea Used rRNA to develop tree of life (found subgroups of prokaryotes that did not fit the other two domains of life, these organisms have different shaped DNA, etc.) Basic cell shapes: Rod shaped, circle shaped, spiral shaped, cama shaped, one more ** refer to lecture slides Pleomorphic = “shape-shifter” having many shapes, these bacteria can keep shifting shapes, from square to star, etc. At a certain point, electrons have to be used to view smaller organelles and proteins, etc. because electrons have shorter wavelengths, so the smaller the object viewed the smaller the wavelength of the electron Chapter 3 –Light Microscopy 9/10/2012 10:27:00 AM better resolution – better wavelength for better magnification total magnification = occur lens x objective lens oil gathers light to make image larger plus more clear / 100x magnification most archaea /bacteria are colourless, so they require contrast refractive index = measure of light-bending ability of a medium resolution limit is 0.2 um (blue wavelength)  result = dark image on light background (no stain) gram positive – thick PG envelop no OM (outer membrane)  stays purples after stained gram negative – thin PG, has OM  return to colourless state after being washed chromosphere – gives off light + absorbs light 1. Fixation – kills cell 2. staining – increases visibility/ contrast 3. Application of Mordant - enhances affinity between dye to cell 4. Decolourization 5. Application of counter stain Roberts postulate was not that if the suspected organism disease upon introducing it into a healthy animal then you can say organism is pathogen, however disease can be caused from syringe or hands, etc. Microbes are part of the domain of life archaea, eukarya, bacteria Light microscope in lab we can see intracellular structures to help distinguish between different organisms Darkfield Light hits bacteria from side (not bottom) so image is formed Light scatters and glow is created around the membrane of the cell result = light image on dark background (no stain) Phase-Contrast Phase of light is altered as it passes through a specimen Image contains regions that are in phase and out of phase Allows detailed examination of internal structures Changes as it hits a sample Result = high contrast dark image on a white background (no stain) Differential Interference Contrast Shadow around bacteria and creates a 3D look Result = high contrast image that appears 3D Fluorescence Def: the ability of substances to absorb short wavelengths and emit them as longer wavelengths 1. natural under UV light 2. Artifical  -fluorchromes (chemical, protein)  Result = fluorescent image on dark background Confocal Lasers excite a fluorochrome stained specimen (single plane at a time) Result = fluorescent 3D image on dark background Atomic Force Microscopy (AFM) Tiny stylus (probe) detects weak repulsive forces of atoms Living and unstained Result = high resolution; 3D image Differential stains uses multiple dyes to distinguish different types of cells Electron Microscopy (EM) Uses electrons instead of light (much shorter wavelength) Live/ not live specimen? Result=? Electron Microscopy: Transmission (TEM) Electron Microscopy Scanning (SEM) Electrons hit glass slide and jump up to form image Electron Microscopy: Cryotomorgraphy Rapid freezing technique to preserve native stat of structures examined in vacuum Images recorded from many different directions to create 3D structure Dipped in liquid nitrogen to freeze Result = naturally preserved (that’s frozen or fixed) extremely high resolution images HELL YEAHHH FUCKEN RIGHT Chapter ??? 2&3 maybe? 9/10/2012 10:27:00 AM Yup! Okay Die Bacteria!!!!!! Characteristics of life: metabolism 1. Metabolism 2. Evolution Microbes and cells can be viewed as biochemical catalysts (metabolism and enzymes) and genetic coding devices Energy sources Lithotroph – uses inorganic molecules as energy source Organotroph – uses organic molecules as energy source Phototroph – uses light molecules as energy source Autotroph – uses CO mo2ecules as energy source Chemoautotroph uses acetate as energy and CO as c2rbon source In stage three: Oxygenic photosynthesis – these organisms can produce a lot more ATP energy , because their membranes are filled with chorophyll (cyanobacteria: anaerobic impact) -during this era when ozone was created and presence of oxygen became available, a lot organisms that could not use oxygen were going extinct Anaerobes – do not require oxygen for growth -obligate: cannot survive in presence of oxygen ex. back of the mouth a lot of microbes cannot receive the oxygen -facultative – can survive in presence of oxygen but don’t use it Microareophiles – requires oxygen to survive, but lower than atmospheric levels **Viruses are not classified in any of the domain of life, because they do not have rRNA Chloroplast and mitochondria both came from bacteria!!! 9/10/2012 10:27:00 AM Motility Types: 1. Flagellar: very rapid rotation up to 110 rev/sec counterclockwise rotation causes forward motion= run clockwise rotation disrupts run causing cell to stop = tumble, these bacteria don’t have eyes, so this type of movement to get to their food and to get around Movement at the molecular level: Rotor – C ring (FliG protein) and MS ring turn and interact with stator Stator – MotA and MotB proteins (form channel through plasma membrane) FliM/N/G proteins initiate switch between CCW and CW based on intercellular signals Flagella increases or decrease rotation speed in direct relation to strength of proton motive force potential midterm question: Do flagella move at a constant speed: No, because it is dependent on the proton motive force 2. Spirochete Flagella remain in periplasmic space inside ou
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