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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