Module 1- introduction to microbiology Flashcards
definition of microbiology
the study of microorganisms
what are microorganisms
-can be unicellular, multicellular or acellular
-microscopic (not visible to naked eye)
why is microbiology important
-terraform the planet by producing oxygen (photosynthetic bacteria)
-backbone of the food chain (fex N req for plant growth)
-cause disease (plant, animal, human)
-promote health (produce vitimans)
-biotechnology and indistries (produce vinegar and medications)
what did our ancestors know about microbes
-traditional knowlage (discovery of rocky mtn spotted fever)
-traditional medicine (moldy bread on skin to treat wounds)
-infrastructures (aqueducts for freshwater, sewage management)
-fermented cheese, yogurt
-acquired immunity
how did our ancestors explain observations on microbes (theories)
-the miasma theory: infectious diseases were cased by bad air (miasma) emitted by rotting organic matter
-the theory of spontaneous generation: living organisms arise form non-living matter
-prevalent ideas in europe and some parts of africa and asia
how did the field of microbiology start
-microscopy started the field
-robert hooke & antonie van leeuwenhoek
robert hooke
-start of microbiology
-published book called micrographia
-described fruting structures of moulds
-first descriptions of microorganisms
antonie van leeuwenhoek
-start of microbiology
-simple microscope
-observed + describe bacteria
-wee animalcules
who was involved with the golden age if microbiology
-louis pasteur
-robert koch
microbial ecology:
-sergei winogradsky
-martinus beijernck
louis pasture
-fermentation: specific microbes, spoilage=unwanted
-pasteurization: kill bad microbes
-vaccines
robert koch
-establish link between disease and microbes
-lab techniques
sergei winogradsky
-microbial ecology
-microorganisms and cross feedings
martinus beijerinck
-microbial ecology
-identified N fixation
after the the microscope was invented what did fermented food beverages turn in to
food microbiology
after the the microscope was invented what did infrastructures turn into
public health measures
after the the microscope was invented what did traditional medicine turn into
modern pharmacology infectious diseases
what are the two types of microbes
cellular microbes and acellular microbes
what falls under cellular microbes
-prokaryotes (bacteria, archaea)
-eukaryotes (protist, fungi, micro-animals)
what falls under acellular microbes
-viruses
-prion
how do we classify microbes
-sequence genes to see how related they are
-look at evolution and see how they are related
-can then make up the phylogenic tree of life
-compared 16S ir 18S rRNA sequence
why aren’t viruses on the tree of life
they lack ribosomal RNA rRNA
what are 70S or 80S ribosomal RNA
-S for theodor Svedberg
-coefficent of sedimentation
-16S=position
-16S to 28S=subunit component
-30S to 60S=small sub unit
-70S to 80S= complete ribosomes
how do we name cellular life
-family, genus, species are italicized
-Escherichia coli when fist appears in text E. coli can be used after that (italicized)
what are the types of microscopes
-light microscope
-electron microscope
-scanning probe microscope (not studied)
what is the most important parameter for microscopy
-resolution
-contrast
-magnification
what makes a microscope powerful
-magnification
-contrast
-resolution
(res+con=sharpness of image)
magnification
-enlarges image
-10x means it is 10x the actual size
-ocular lends x objective lens=total magnification
-zooming in on poor quality image gives pixels
resolution
-distinguish two adjacent objects
-limitation due to wave lengths (shorter=better)
-visible light vs electron:
-light=0.2 micrometers
-electron=0.2 nanometer
contrast
-difference in brightness between structures
features of light or electrons
light microscope: bright field
-dark image on light background
-cells absorb and scatter light differently than surrounding
drawback to bright field microscope
-lack contrast/resolution
-not effective tool unless cells are stained
if you have 10x ocular lends and 40x objective lends what is the total magnification
400x
what are the ways we can fix bacteria to a slide
-easiest: heat
-more complex: chemical (formeldehyde)
how can we see bacteria more easily
staining
simple step staining
-step one: fixing the sample
-second step: add the stain (color)
-third step: rinse the sample
different simple staining methods:
-basic stain (crystal violet)
-acid stain (rose bengal)
-negative stain (nigrosine)
what is a basic stain for
- charged molecs and structures
what is acid stain for
+ charged molecs and structures
what is negative stain for
to stain the background
what would happen if we used basic and acidic stain for a bacterial sample
-each dye would bind to specific structures and help differentiate structures
what is differential staining
-use two or more dyes
-helps characterize bacteria and/or identify specific structures
-gram stain (neg bacteria with or without outer membrane)
-acid fast stain (gram pos with or without outer membrane
steps on how to gram stain
-step 1: crystal violet, primary stain added to specimen smear, stains cells purple or blue
-step 2: iodine, mordant makes dye less soluble so it adheres to cells walls, cells remail blue or purple
-step 3: alcohol, decolorizer washes away stain from gram-negative cellwalls, gram pos cells remain purple or blue, gram neg cells are colourless
-step 4: safranin, counterstain allows dye adherence to gram-neg cells, gram pos cells remain purple or blue, gram neg appear pink or red
gram positive bacteria stain
-purple
-thick cells wall that is exposed to the external environment (no outer membrane)
gram negative bacteria stain
-pink
-has a thinner cells wall that is protected from the external environment by the outer membrane
if you skip the alcohol step what would the color of the gram negative be
purple
how to acid-fast stain bacteria
-before youll have a transparent bacteria
-add carbol fuchsin stain (primary stain) crating a fuchsia
-rinse with alcohol (decolorizer of acid fast stain), acid-fast bacteria will be fuchsia, non-acid fast will be transparent
-add methylene blue (counterstain), AFB=purple non-AFB=blue/purple
how can you identify different stuctures
differential staining
how would you improve resolution and contrast (without staining) of light microscope
changing property of light source
light microscope: dark field
-modified condenser
-creates hollow cone
-light does not pass through the specimen
-light is scattered by specimen
-refracted or reflected by light
-bright object on dark background
dark field microscopy vs light field
-dark field has:
-better resolution (living samples)
-resolved some object
-good way to observe motility
light microscopy- phase contrast
-annular ring
-alters property of light
-light passes through the specimen
-uses refraction and interference
-“white glow” objects on dark background
phase contrast vs bright field
-phase contrast has:
-better resolution and contrast (living samples)
-visual specialized structures: organelles or eukaryotes, endospores of gram positive
you discover new types of bacteria and suspect it forms endospores, what type of microscopy can be used to observe in real time
phase contrast microscopy with out stain, stain kills
light microscopy- fluorescences
-fluorochromes (natural or added)
-excitation with a light source (UV of blue light)
-emits visible light
-filtered out exciting light
fluorescent staining
-sample preparation
-fixed (dried or sectioned)
-living or dehydrated
-dies are fluorochromes
-attach fluorochromes to:
-antibodies (immunofluorescence)
-Lectins
-DNA
-florescent proteins
how to improve resolution and magnification function of microscope
-decrease wave length of the source of your illumination
electron microscopy
-higher resolution than light
-TEM: high resolution and magnification
-you dont get pixels
-samples are dead: freeze/dehydrates and thinly slices because electron do not penetrate thick samples
-sub-cellular structures
-molecular structures
TEM vs light microscopy
exact same but TEM uses electrons light uses light
TEM vs scanning electron microscopy (SEM)
-for SEM electrons “bounce” on sample
-give 3D appearence
what is the best aplication to look at viruses
transmission electron microscope (very small)
