Assignment Micro Biology

8/14/2019 Assignment Micro Biology

1/15

DIVYA MANASVI RAJ MEHTAMicrobiology Assignment

Topic: Introduction to Pharmaceutical Microbiology

Definition:Microbiology is the study ofmicroorganisms, which are unicellular or cell-

cluster microscopicorganisms. This includes eukaryotes such as fungi and prostates,andprokaryotes.Viruses, though not strictly classed as living organisms, are alsostudied. In short; microbiology refers to the study of life and organisms that are too smallto be seen with the naked eye.

Introduction:

Microbiology typically includes the study of the immune system,orImmunology. Generally, immune systems interact withpathogenic microbes; these twodisciplines often intersect which is why many colleges offer a paired degree such as"Microbiology and Immunology".Microbiology is a broad term which includes virology, mycology,parasitological,bacteriology and other branches.
http://en.wikipedia.org/wiki/Microorganismshttp://en.wikipedia.org/wiki/Microorganismshttp://en.wikipedia.org/wiki/Unicellularhttp://en.wikipedia.org/wiki/Microscopichttp://en.wikipedia.org/wiki/Organismhttp://en.wikipedia.org/wiki/Fungihttp://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Immunologyhttp://en.wikipedia.org/wiki/Immunologyhttp://en.wikipedia.org/wiki/Pathogenhttp://en.wikipedia.org/wiki/Pathogenhttp://en.wikipedia.org/wiki/Virologyhttp://en.wikipedia.org/wiki/Mycologyhttp://en.wikipedia.org/wiki/Mycologyhttp://en.wikipedia.org/wiki/Parasitologyhttp://en.wikipedia.org/wiki/Microorganismshttp://en.wikipedia.org/wiki/Unicellularhttp://en.wikipedia.org/wiki/Microscopichttp://en.wikipedia.org/wiki/Organismhttp://en.wikipedia.org/wiki/Fungihttp://en.wikipedia.org/wiki/Prokaryotehttp://en.wikipedia.org/wiki/Virushttp://en.wikipedia.org/wiki/Immunologyhttp://en.wikipedia.org/wiki/Pathogenhttp://en.wikipedia.org/wiki/Virologyhttp://en.wikipedia.org/wiki/Mycologyhttp://en.wikipedia.org/wiki/Parasitology


2/15

Microbiology is researched actively, and the field is advancing continually.We have probably only studied about one percent of all of the microbe species on Earth.Although microbes were directly observed over three hundred years ago, the field ofmicrobiology can be said to be in its infancy relative to older biological disciplines suchas zoologyand botany.

Scope:The field of microbiology can be generally divided into several sub disciplines:

Microbial physiology: The study of how the microbial cell functions biochemically.Includes the study of microbial growth, microbial metabolism andmicrobial cell structure.

Microbial genetics: The study of how genes are organized and regulated in microbes inrelation to their cellular functions. Closely related to the field ofmolecular biology.

Cellular microbiology: A discipline bridging microbiology andcell biology.

Medical microbiology: The study of the pathogenic microbesand the role of microbes inhuman illness. Includes the study of microbial pathogenesis and epidemiology and isrelated to the study of disease pathology and immunology.

Veterinary microbiology: The study of the role in microbes in veterinary medicineoranimaltaxonomy.

Environmental microbiology: The study of the function and diversity of microbes in theirnatural environments. Includes the study ofmicrobial ecology, microbial-mediatednutrient cycling,geomicrobiology, microbial diversity andbioremediation.

Characterisation of key bacterial habitats such asthe rhizosphere and phyllosphere, soil and groundwaterecosystems, open oceans orextreme environments (extremophiles).Evolutionary microbiology: The study of the evolution of microbes. Includes the study ofbacterial systematicsand taxonomy.

Industrial microbiology: The exploitation of microbes for use in industrial processes.Examples includeindustrial fermentation andwastewater treatment. Closely linked tothebiotechnology industry. This field also includes brewing, an important application ofmicrobiology.

Aeromicrobiology: The study of airborne microorganisms.

Food microbiology: The study of microorganisms causing food spoilage and food borneillness. Using microorganisms to produce foods, for example by fermentation.

Pharmaceutical microbiology:The study of microorganisms causing pharmaceuticalcontamination and spoil
http://en.wikipedia.org/wiki/Zoologyhttp://en.wikipedia.org/wiki/Zoologyhttp://en.wikipedia.org/wiki/Botanyhttp://en.wikipedia.org/w/index.php?title=Microbial_physiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Metabolismhttp://en.wikipedia.org/wiki/Bacterial_cell_structurehttp://en.wikipedia.org/wiki/Bacterial_cell_structurehttp://en.wikipedia.org/wiki/Microbial_geneticshttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Molecular_biologyhttp://en.wikipedia.org/wiki/Molecular_biologyhttp://en.wikipedia.org/wiki/Cellular_microbiologyhttp://en.wikipedia.org/wiki/Cell_biologyhttp://en.wikipedia.org/wiki/Cell_biologyhttp://en.wikipedia.org/wiki/Medical_microbiologyhttp://en.wikipedia.org/wiki/Pathogenic_microbeshttp://en.wikipedia.org/wiki/Pathogenic_microbeshttp://en.wikipedia.org/wiki/Pathogenesishttp://en.wikipedia.org/wiki/Epidemiologyhttp://en.wikipedia.org/wiki/Pathologyhttp://en.wikipedia.org/wiki/Immunologyhttp://en.wikipedia.org/w/index.php?title=Veterinary_microbiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Veterinary_medicinehttp://en.wikipedia.org/wiki/Veterinary_medicinehttp://en.wikipedia.org/wiki/Taxonomyhttp://en.wikipedia.org/wiki/Taxonomyhttp://en.wikipedia.org/wiki/Environmental_microbiologyhttp://en.wikipedia.org/wiki/Microbial_ecologyhttp://en.wikipedia.org/wiki/Microbial_ecologyhttp://en.wikipedia.org/wiki/Nutrient_cyclehttp://en.wikipedia.org/wiki/Nutrient_cyclehttp://en.wikipedia.org/wiki/Geomicrobiologyhttp://en.wikipedia.org/wiki/Geomicrobiologyhttp://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Rhizospherehttp://en.wikipedia.org/wiki/Phyllospherehttp://en.wikipedia.org/wiki/Soilhttp://en.wikipedia.org/wiki/Groundwaterhttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Oceanshttp://en.wikipedia.org/wiki/Extremophilehttp://en.wikipedia.org/w/index.php?title=Evolutionary_microbiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Systematicshttp://en.wikipedia.org/wiki/Systematicshttp://en.wikipedia.org/wiki/Taxonomyhttp://en.wikipedia.org/wiki/Industrial_microbiologyhttp://en.wikipedia.org/wiki/Industrial_fermentationhttp://en.wikipedia.org/wiki/Industrial_fermentationhttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Biotechnologyhttp://en.wikipedia.org/wiki/Brewinghttp://en.wikipedia.org/w/index.php?title=Aeromicrobiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Food_microbiologyhttp://en.wikipedia.org/wiki/Pharmaceutical_microbiologyhttp://en.wikipedia.org/wiki/Zoologyhttp://en.wikipedia.org/wiki/Botanyhttp://en.wikipedia.org/w/index.php?title=Microbial_physiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Metabolismhttp://en.wikipedia.org/wiki/Bacterial_cell_structurehttp://en.wikipedia.org/wiki/Microbial_geneticshttp://en.wikipedia.org/wiki/Genehttp://en.wikipedia.org/wiki/Molecular_biologyhttp://en.wikipedia.org/wiki/Cellular_microbiologyhttp://en.wikipedia.org/wiki/Cell_biologyhttp://en.wikipedia.org/wiki/Medical_microbiologyhttp://en.wikipedia.org/wiki/Pathogenic_microbeshttp://en.wikipedia.org/wiki/Pathogenesishttp://en.wikipedia.org/wiki/Epidemiologyhttp://en.wikipedia.org/wiki/Pathologyhttp://en.wikipedia.org/wiki/Immunologyhttp://en.wikipedia.org/w/index.php?title=Veterinary_microbiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Veterinary_medicinehttp://en.wikipedia.org/wiki/Taxonomyhttp://en.wikipedia.org/wiki/Environmental_microbiologyhttp://en.wikipedia.org/wiki/Microbial_ecologyhttp://en.wikipedia.org/wiki/Nutrient_cyclehttp://en.wikipedia.org/wiki/Geomicrobiologyhttp://en.wikipedia.org/wiki/Bioremediationhttp://en.wikipedia.org/wiki/Rhizospherehttp://en.wikipedia.org/wiki/Phyllospherehttp://en.wikipedia.org/wiki/Soilhttp://en.wikipedia.org/wiki/Groundwaterhttp://en.wikipedia.org/wiki/Ecosystemhttp://en.wikipedia.org/wiki/Oceanshttp://en.wikipedia.org/wiki/Extremophilehttp://en.wikipedia.org/w/index.php?title=Evolutionary_microbiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Systematicshttp://en.wikipedia.org/wiki/Taxonomyhttp://en.wikipedia.org/wiki/Industrial_microbiologyhttp://en.wikipedia.org/wiki/Industrial_fermentationhttp://en.wikipedia.org/wiki/Wastewater_treatmenthttp://en.wikipedia.org/wiki/Biotechnologyhttp://en.wikipedia.org/wiki/Brewinghttp://en.wikipedia.org/w/index.php?title=Aeromicrobiology&action=edit&redlink=1http://en.wikipedia.org/wiki/Food_microbiologyhttp://en.wikipedia.org/wiki/Pharmaceutical_microbiology


3/15


4/15

a wide range of habitats from hot springs to the icy wastes of Antarctica and inside thebodies of animals and plants. Microbes cause diseases like 'flu or malaria, but most arecompletely harmless.

They are essential to the cycling of nutrients in the ecosystems of the planet.

Microbial activity is exploited for the benefit of humankind in many ways, such as theproduction of medicines, food and enzymes, in the clean-up of sewage and other wastes andin the exciting advances resulting from developments in molecular biology techniques.

Until the middle of the 19th century all living organisms were classified into twogroups, animals and plants. There were problems with this simplistic system, for examplefungi look like plants but they do not photosynthesise. Over the years, a number ofclassification systems were put forward; the most well known is the Five Kingdom systemwhich groups all living things by cell type, level of organization and nutrition as follows:

1. Animals

2. Plants3. Fungi4. Protoctista (algae and protozoa)5. Monera (bacteria)

The first four groups represent eukaryotes (cells have a nucleus and membrane-boundorganelles). The Monera includes all prokaryotes (cells lack a nucleus and membrane-bound organelles).

In the light of recent advances in molecular biology, which allow the comparison of thesequencing of ribosomal RNA of organisms, a new classification system is preferred byscientists. It is based on three lines of descent from a common ancestor. Each group iscalled a Domain:

1.Bacteria (true bacteria) - prokaryotes2. Archaea (archaebacteria) - prokaryotes3. Eukarya eukaryotes


5/15

The archaebacteria are prokaryotic in general structure and share many bacterialcharacteristics. However they share with eukaryotes a some ribosomal sequences that arenot found in bacteria.

Viruses are not usually included in classification systems as they are non-cellular and theyare dependent on a host cell for their replication and metabolic processes.Within their domains, identification of microbes begins with their physical appearance,followed by biochemical and genetic tests.

Bacteria:

Bacteria consist of only one cell, but they're a very complex group of livingthings. Some bacteria can live in temperatures above the boiling point and in cold belowthe freezing point.

There are thousands of species of bacteria, but all of them are basically one ofthree different shapes. Some are rod- or stick-shaped; others are shaped like little balls.Others still are helical or spiral in shape. Some bacteria cells exist as individuals whileothers cluster together to form pairs, chains, squares or other groupings.

Some bacteria can make their own food from sunlight, just like plants. Alsolike plants, they give off oxygen. Other bacteria absorb food from the material they live onor in. Some of these bacteria can live off iron or sulfur! The bacteria that live in yourstomach absorb nutrients from the digested food you've eaten.Some bacteria move about their environment by means of long, whip-like structures called

flagella. They rotate their flagella like tiny outboard motors to propel themselves throughliquid environments. They may also reverse the direction in which their flagella rotate sothat they tumble about in one place. Other bacteria secrete a slime layer and ooze oversurfaces like slugs. Others stay almost in the same spot.Bacteria live on or in just about every material and environment on Earth from soil towater to air, and from your body to the Arctic ice to the Sahara deserts. Each squarecentimeter of your skin averages about 100,000 bacteria. A single teaspoon of soil containsmore than a billion (1,000,000,000) bacteria.


6/15

Stucture of Bacterial Cell:


7/15

Viruses: A virus is too small to be seen without a microscope. A virus is basically a tinybundle of genetic material carried in a shell called the viral coat. Some viruses have anadditional layer around this coat called an envelope. That's basically all there is to viruses.

There are thousands of different viruses that come in many shapes. Many aremulti-sided or polyhedral. If you've ever looked closely at a cut gem, like the diamond in anengagement ring, you've seen an example of a polyhedral shape. Unlike the diamond in aring, however, a virus does not taper to a point, but is shaped the same all around. Otherviruses are shaped like spiky ovals or bricks with rounded corners. Some are like skinnysticks while others look like pieces of looped string. Some are more complex and shapedlike little spaceship landing pods.

Viruses are found on or in just about every material and environment on Earthfrom soil to water to air. They're basically found anywhere there are cells to infect. Viruses

can infect every living thing. However, viruses tend to be somewhat picky about what typeof cells they infect. Plant viruses are not equipped to infect animal cells, for example,though a certain plant virus could infect a number of related plants. Sometimes, a virusmay infect one animal and do no harm, but cause a great deal of damage when it gets into adifferent but closely related animal.Viruses exist to reproduce only. To do that, they have to take over suitable host cells. Uponlanding on a suitable host cell, a virus gets its genes inside the cell either by tricking thehost cell to pull it inside, or by connecting its viral coat with the host cell wall or membraneand releasing its genes inside, or by injecting their genes into the host cell's DNA.

The viral genes are then copied many times, using the process the host cell

would normally use to reproduce its own DNA. The new viral genes then come togetherand assemble into whole new viruses. The new viruses are either released from the host cellwithout destroying the cell or eventually build up to a large enough number that they burstthe host cell.

Stucture of a Virus:


8/15

Electron Microscopy:Transmission electron microscope (TEM):

The original form of electron microscope,the transmission electron microscope (TEM) uses a high voltageelectron beam to create animage. The electrons are emitted by an electron gun, commonly fitted witha tungsten filament cathode as the electron source. The electron beam is accelerated byan anode typically at +100 keV (40 to 400 keV) with respect to the cathode, focusedby electrostatic and electromagneticlenses, and transmitted through the specimen that is inpart transparent to electrons and in part scattersthem out of the beam. When it emergesfrom the specimen, the electron beam carries information about the structure of thespecimen that is magnified by the objective lens system of the microscope. The spatialvariation in this information (the "image") is viewed by projecting the magnified electron

image onto a fluorescent viewing screen coated with a phosphor or scintillator materialsuch as zinc sulfide. The image can be photographically recorded by exposinga photographic film or plate directly to the electron beam, or a high-resolution phosphormay be coupled by means of a lens optical system or a fibre optic light-guide to the sensorof a CCD (charge-coupled device) camera. The image detected by the CCD may bedisplayed on a monitor or computer.

Resolution of the TEM is limited primarily by spherical aberration, but a newgeneration of aberration correctors have been able to partially overcome sphericalaberration to increase resolution. Hardware correction of spherical aberration for the HighResolution TEM (HRTEM) has allowed the production of images with resolution below

0.5 ngstrm (50picometres at magnifications above 50 million times. The ability todetermine the positions of atoms within materials has made the HRTEM an important toolfor nano-technologies research and development.

Scanning electron microscope (SEM):
http://en.wikipedia.org/wiki/Transmission_electron_microscopehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electron_beamhttp://en.wikipedia.org/wiki/Electron_gunhttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Cathodehttp://en.wikipedia.org/wiki/Anodehttp://en.wikipedia.org/wiki/Electronvolthttp://en.wikipedia.org/wiki/Electrostatichttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Electron_scatteringhttp://en.wikipedia.org/wiki/Electron_scatteringhttp://en.wikipedia.org/wiki/Objective_lenshttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Scintillatorhttp://en.wikipedia.org/wiki/Photographic_filmhttp://en.wikipedia.org/wiki/Photographic_platehttp://en.wikipedia.org/wiki/Fibre_optichttp://en.wikipedia.org/wiki/Charge-coupled_devicehttp://en.wikipedia.org/wiki/Spherical_aberrationhttp://en.wikipedia.org/wiki/Spherical_aberrationhttp://en.wikipedia.org/wiki/HRTEMhttp://en.wikipedia.org/wiki/%C3%85ngstr%C3%B6mhttp://en.wikipedia.org/wiki/Picometrehttp://en.wikipedia.org/wiki/Picometrehttp://en.wikipedia.org/wiki/Transmission_electron_microscopehttp://en.wikipedia.org/wiki/Voltagehttp://en.wikipedia.org/wiki/Electron_beamhttp://en.wikipedia.org/wiki/Electron_gunhttp://en.wikipedia.org/wiki/Tungstenhttp://en.wikipedia.org/wiki/Cathodehttp://en.wikipedia.org/wiki/Anodehttp://en.wikipedia.org/wiki/Electronvolthttp://en.wikipedia.org/wiki/Electrostatichttp://en.wikipedia.org/wiki/Electromagnetismhttp://en.wikipedia.org/wiki/Electron_scatteringhttp://en.wikipedia.org/wiki/Objective_lenshttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Scintillatorhttp://en.wikipedia.org/wiki/Photographic_filmhttp://en.wikipedia.org/wiki/Photographic_platehttp://en.wikipedia.org/wiki/Fibre_optichttp://en.wikipedia.org/wiki/Charge-coupled_devicehttp://en.wikipedia.org/wiki/Spherical_aberrationhttp://en.wikipedia.org/wiki/HRTEMhttp://en.wikipedia.org/wiki/%C3%85ngstr%C3%B6mhttp://en.wikipedia.org/wiki/Picometre


9/15

Unlike the TEM, where electrons of the highvoltage beam carry the image of the specimen, the electron beam of the Scanning ElectronMicroscope(SEM)[9]does not at any time carry a complete image of the specimen. TheSEM produces images by probing the specimen with a focused electron beam that isscanned across a rectangular area of the specimen (raster scanning). At each point on the

specimen the incident electron beam loses some energy, and that lost energy is convertedinto other forms, such as heat, emission oflow-energy secondary electrons, light emission(cathodoluminescence) or x-ray emission. The display of the SEM maps the varyingintensity of any of these signals into the image in a position corresponding to the position ofthe beam on the specimen when the signal was generated. In the SEM image of an antshown at right, the image was constructed from signals produced by a secondary electrondetector, the normal or conventional imaging mode in most SEMs.Generally, the image resolution of an SEM is about an order of magnitude poorer than thatof a TEM. However, because the SEM image relies on surface processes rather thantransmission, it is able to image bulk samples up to many centimetres in size and(depending on instrument design and settings) has a great depth of field, and so can

produce images that are good representations of the three-dimensional shape of the sample.

Reflection electron microscope (REM):

In the Reflection Electron Microscope (REM) asin the TEM, an electron beam is incident on a surface, but instead of using the transmission(TEM) or secondary electrons (SEM), the reflected beam ofelastically scattered electrons isdetected. This technique is typically coupled with Reflection High Energy ElectronDiffraction (RHEED) and Reflection high-energy loss spectrum (RHELS). Anothervariation is Spin-Polarized Low-Energy Electron Microscopy (SPLEEM), which is used forlooking at the microstructure ofmagnetic domains.

Scanning transmission electron microscope (STEM):

The STEM rasters a focusedincident probe across a specimen that (as with the TEM) has been thinned to facilitatedetection of electrons scattered through the specimen. The high resolution of the TEM isthus possible in STEM. The focusing action (and aberrations) occur before the electrons hitthe specimen in the STEM, but afterward in the TEM. The STEMs use of SEM-like beamrastering simplifies annular dark-field imaging, and other analytical techniques, but alsomeans that image data is acquired in serial rather than in parallel fashion.

Low voltage electron microscope (LVEM):

The low voltage electron microscope (LVEM) is acombination of SEM, TEM and STEM in one instrument, which operated at relatively lowelectron accelerating voltage of 5 kV. Low voltage increases image contrast which isespecially important for biological specimens. This increase in contrast significantly
http://en.wikipedia.org/wiki/Scanning_Electron_Microscopehttp://en.wikipedia.org/wiki/Scanning_Electron_Microscopehttp://en.wikipedia.org/wiki/Electron_microscope#cite_note-8%23cite_note-8http://en.wikipedia.org/wiki/Electron_microscope#cite_note-8%23cite_note-8http://en.wikipedia.org/wiki/Raster_scanhttp://en.wikipedia.org/wiki/Secondary_emissionhttp://en.wikipedia.org/wiki/Secondary_emissionhttp://en.wikipedia.org/wiki/Cathodoluminescencehttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Elastic_scatteringhttp://en.wikipedia.org/wiki/RHEEDhttp://en.wikipedia.org/wiki/RHEEDhttp://en.wikipedia.org/wiki/Magnetic_domainhttp://en.wikipedia.org/wiki/Magnetic_domainhttp://en.wikipedia.org/wiki/Annular_dark-field_imaginghttp://en.wikipedia.org/wiki/Low_voltage_electron_microscopehttp://en.wikipedia.org/wiki/Scanning_Electron_Microscopehttp://en.wikipedia.org/wiki/Scanning_Electron_Microscopehttp://en.wikipedia.org/wiki/Electron_microscope#cite_note-8%23cite_note-8http://en.wikipedia.org/wiki/Raster_scanhttp://en.wikipedia.org/wiki/Secondary_emissionhttp://en.wikipedia.org/wiki/Cathodoluminescencehttp://en.wikipedia.org/wiki/X-rayhttp://en.wikipedia.org/wiki/Elastic_scatteringhttp://en.wikipedia.org/wiki/RHEEDhttp://en.wikipedia.org/wiki/RHEEDhttp://en.wikipedia.org/wiki/Magnetic_domainhttp://en.wikipedia.org/wiki/Annular_dark-field_imaginghttp://en.wikipedia.org/wiki/Low_voltage_electron_microscope


10/15

reduces, or even eliminates the need to stain. Sectioned samples generally need to bethinner than they would be for conventional TEM (20-65nm). Resolutions of a few nm arepossible in TEM, SEM and STEM modes.

Dark Field Microscopy:

Dark field microscopy (dark ground microscopy) describesmicroscopy methods, in both light and electron microscopy, which exclude the unscatteredbeam from the image. As a result, the field around the specimen (i.e. where there is nospecimen to scatter the beam) is generally dark.

Dark field microscopy is a very simple yet effectivetechnique and well suited for uses involving live and unstained biological samples, such as asmear from a tissue culture or individual water-borne single-celled organisms. Considering

the simplicity of the setup, the quality of images obtained from this technique is impressive.The main limitation of dark field microscopy is the low light

levels seen in the final image. This means the sample must be very strongly illuminated,which can cause damage to the sample.Dark field microscopy techniques are almost entirely free of artifacts, due to the nature ofthe process. However the interpretation of dark field images must be done with great careas common dark features ofbright field microscopy images may be invisible, and viceversa.

While the dark field image may first appear to be anegative of the bright field image, different effects are visible in each. In bright fieldmicroscopy, features are visible where either a shadow is cast on the surface by the incidentlight, or a part of the surface is less reflective, possibly by the presence of pits or scratches.Raised features that are too smooth to cast shadows will not appear in bright field images,but the light that reflects off the sides of the feature will be visible in the dark field images.

Applications:

Conventional darkfield imaging:

Briefly, conventional darkfield imaging involves tiltingthe incident illumination until a diffracted, rather than the incident, beam passes through asmall objective aperture in the objective lens back focal plane. Darkfield images, underthese conditions, allow one to map the diffracted intensity coming from a single collectionof diffracting planes as a function of projected position on the specimen, and as a functionof specimen tilt.
http://en.wikipedia.org/wiki/Staining_(biology)http://en.wikipedia.org/wiki/Bright_field_microscopyhttp://en.wikipedia.org/wiki/Staining_(biology)http://en.wikipedia.org/wiki/Bright_field_microscopy


11/15

In single crystal specimens, single-reflection darkfield images of a specimen tilted just offthe Bragg condition allow one to "light up" only those lattice defects, like dislocations orprecipitates, which bend a single set of lattice planes in their neighborhood. Analysis ofintensities in such images may then be used to estimate the amount of that bending. Inpolycrystalline specimens, on the other hand, darkfield images serve to light up only that

subset of crystals which is Bragg reflecting at a given orientation.

Weak beam imaging:

Weak beam imaging involves optics similar to conventionaldarkfield, but use of a diffracted beam harmonic rather than the diffracted beam itself.Much higher resolution of strained regions around defects can be obtained in this way.

Low and high angle annular darkfield imaging:

Annular darkfield imaging requires oneto form images with electrons diffracted into an annular aperture centered on, but notincluding, the unscattered beam. For large scattering angles in a scanning transmissionelectron microscope, this is sometimes called Z-contrast imaging because of the enhancedscattering from high atomic number atoms.

Phase Contrast Microscopy:Phase contrast microscopy is anoptical

microscopyillumination technique in which smallphase shifts in the light passing througha transparent specimen are converted into amplitudeor contrast changes in the image.

A phase contrast microscope does not requirestaining to view the slide. This typeof microscope made it possible to study the cell cycle.As light travels through a medium other thanvacuum, interaction with this medium causesits amplitude andphase to change in a way which depends on properties of the medium.Changes in amplitude give rise to familiar absorption of light which gives rise to colours

when it is wavelength dependent. The human eye measures only the energy of light arrivingon the retina, so changes in phase are not easily observed, yet often these changes in phasecarry a large amount of information.The same holds in a typical microscope, i.e., although the phase variations introduced bythe sample are preserved by the instrument (at least in the limit of the perfect imaginginstrument) this information is lost in the process which measures the light.
http://en.wikipedia.org/wiki/Scanning_transmission_electron_microscopehttp://en.wikipedia.org/wiki/Scanning_transmission_electron_microscopehttp://en.wikipedia.org/wiki/Scanning_transmission_electron_microscopehttp://en.wikipedia.org/wiki/Optical_microscopyhttp://en.wikipedia.org/wiki/Optical_microscopyhttp://en.wikipedia.org/wiki/Optical_microscopyhttp://en.wikipedia.org/wiki/Illuminationhttp://en.wikipedia.org/wiki/Phase_shiftshttp://en.wikipedia.org/wiki/Phase_shiftshttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Contrasthttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Staininghttp://en.wikipedia.org/wiki/Staininghttp://en.wikipedia.org/wiki/Cell_cyclehttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Phase_(waves)http://en.wikipedia.org/wiki/Scanning_transmission_electron_microscopehttp://en.wikipedia.org/wiki/Scanning_transmission_electron_microscopehttp://en.wikipedia.org/wiki/Optical_microscopyhttp://en.wikipedia.org/wiki/Optical_microscopyhttp://en.wikipedia.org/wiki/Illuminationhttp://en.wikipedia.org/wiki/Phase_shiftshttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Contrasthttp://en.wikipedia.org/wiki/Microscopehttp://en.wikipedia.org/wiki/Staininghttp://en.wikipedia.org/wiki/Cell_cyclehttp://en.wikipedia.org/wiki/Vacuumhttp://en.wikipedia.org/wiki/Amplitudehttp://en.wikipedia.org/wiki/Phase_(waves)


12/15

In order to make phase variations observable, it is necessary to combine the lightpassing through the sample with a reference so that the resulting interference reveals thephase structure of the sample.

Common Communicable Diseases:

Sr.No. Name ofDisease

Mode ofSpread

Incubationperiod

Symptoms Managementof the Patient

1. Cholera Food andWater

1-5 days (i) Suddenonset ofsevere,waterydiarrhoea.The faeceslook like rice

water(ii) Vomitting(iii) Crampsin the legs(iv) Patientfeels verythirsty

Dehydrationcan bedangerous,so give plentyof fluids. GiveOralrehydration

solution(ORS).

2. Typhoid Food andWater

14-21 days (i) Severeheadache(ii) Feverwith lowpulse(iii) Dry white

coated tongue

Blood cultureand othertestsshould bedone. Give theprescribed

medication tothe patient.

3. Hepatitis(jaundice)

Food andWater

20-35 days (i) Fever(ii) Darkyellow urine(iii) Yellowishtinge in eyes(iv) Generalpaleness

Give acarbohydratesrich diet.Keep thepatient in bedas longas there isfever and tillappetitereturns tonormal.

4. Influenza(Flu) Air 1-3 days (i) Fever(ii) Cold,cough,sneezing(iii) Headacheand bodyache(iv) Nausea

Control thefever withmedicinesand coughwith steaminhalation.

5. Tuberculosis(T.B)

Air 4-6 days (i) Persistentcough

Treatment isprolonged so


13/15

(ii) Loss ofweight andappetite(iii) Excessiveweakness(iv) Rapid

pulse(v) Chest pain(vi) Breathhas bad smell

constantmonitoring bythe doctoris essential.

6. Malaria Mosquitobite

10-14 days (i) Fever(ii)Alternatingchill andperspiration(iii) Headacheand bodyache(iv) Nausea(v) Vomiting

Get the bloodtest done toconfirmmalaria. Thengiveprescribedmedicines

7.Tetanus Wound

exposed todust orrusted item

4 days to 2weeks

(i)Restlessness(ii) Headache(iii) Fever0(iv) Stff neck(v) Difficultyin chewingandswallowing(vi) Spasm ofmuscles of

jaw and face(vii) Bendingof back in

shape of bow(viii)Severepain

Put a ball ofcottonbetween teethto preventbiting oftongue.

Bacterial Resistance:

Our bodys immune system uses specially designed cells tolocate and shut down microscopic invaders like bacteria, usually stopping them before they

can cause trouble. We get sick what is called a bacterial infection when bacteria inour body reproduce faster than our immune system can kill them.

Antibiotics are powerful bacteria-killing drugs that help our bodies regain the upper handwhen a bacterial infection develops. Today, there are hundreds of antibiotics in use, mosttailored to treat a specific kind of bacterial infection. (Thats why taking unused antibioticsprescribed for one kind of bacterial infection wont necessarily work against another.Never save anti-biotics; always finish the full course of treatment as prescribed.)


14/15

Doctors have noticed that some bacteria are getting tougher to kill. The usual antibioticdrugs dont seem to work as well or work at all. Such bacteria are said to be resistant.Bacterial resistance makes an infection much harder to treat. Higher doses or stronger

drugs may be required. In extreme cases, bacterial resistance can be fatal.xperts like the scientists at the Centers for Disease Control and Prevention (CDC) agreethat the overprescription and misuse of anti-biotic drugs are the main causes of bacterialresistance. The CDC says that up to half of the roughly 100 million prescriptions forantibiotics written each year are unnecessary.

Other causes for Bacterial Resistance:

Bacteria reproduce by dividing to create copies of themselves; sometimes the copiesarent exact and the new organism has different characteristics than the original.These characteristics could make the new organism resistant to an antibiotic.

Bacteria have the ability to share resistant characteristics with each other outsideof reproduction. This makes it possible to transfer resistance from one person toanother through exposure to resistant bacteria.

Bacterial resistance in humans may be increased by the use of preventive antibioticsin animal feed. In 1995, an estimated 4.5 million pounds of antibiotics were used toreduce the spread of disease and enhance the growth of cattle, swine and poultry.The U.S. Food and Drug Administration (FDA) is now reviewing this practice todetermine its potential health impact.

The U.S. Food and Drug Administration (FDA) convened a panel of experts toexamine the possible role of antibacterial hand and body wash products inpromoting bacterial resistance. The panel reviewed the available science anddetermined that antibacterial wash products were not a public health concern.

Tips for fighting bacterial resistance:

1. Never take an antibiotic for viral infections such as colds or flu.Dont ask your doctor to prescribe antibiotics if he or she doesnt think they are

necessary.

2. If an antibiotic is called for, use it exactly as the doctor prescribes.Follow the doctors treatment instructions and finish the full amount of antibioticprescribed. Dont stop taking the medication just because you are feeling better. Never saveanti-biotics to treat yourself or others later.

3. Always wash your hands thoroughly.


15/15

Scrub your hands vigorously for 10 to 15 seconds using soap and warm water. Manyleading brands have the word antibacterial on the label. (Remember to wash betweenyour fingers, where germs accumulate.)

4. Always handle food correctly.

Basic sanitation and proper food handling can go a long way toward preventing foodborneillness.Stay safe:Keep your hands, utensils and food preparation surfaces clean.Avoid cross-contamination; dont let raw meat, poultry and fish or their juices comeinto contact with other foods.Cook foods to the proper temperature to kill off dangerous microorganisms.Refrigerate foods promptly to keep harmful bacteria from growing and multiplying.

5. Get vaccinated.If youre 65 or older or you have a chronic illness, you should get vaccinated for

pneumococcal pneumonia. Its a major cause of death in older adults.

Bibliography

www.wikipedia.org/microbiology

www.wikipedia.org/microscopy

www.textbookof bacteriology.net

www.nclnet.org/microbes
http://www.wikipedia.org/microbiologyhttp://www.wikipedia.org/microscopyhttp://www.wikipedia.org/microbiologyhttp://www.wikipedia.org/microscopy

Assignment Micro Biology

Documents

Transcript of Assignment Micro Biology