Examining something under a microscope requires the microbiologist to consider p
ID: 189168 • Letter: E
Question
Examining something under a microscope requires the microbiologist to consider potential problems associated with viewing each specimen, and then to evaluate the pluses and minuses of several different microscopy techniques. For each of the following specimens, first describe the problems inherent in viewing the specimen. Then consider at least TWO types of microscope that could reasonably be used to view the specimen. Make a table that lists (1) how that particular microscope works, and (2) at least two pluses and two minuses associated with each of your microscope choices.
A. Motile bacterial cells swimming
B. Bacteriophage inside host cells
C. Bacterial slime layer
D. Bacterial biofilm forming on a plant leaf
Explanation / Answer
Motile bacterial cell swimming
Bacterial cells are very small and cannot visible at naked eyes. Motile cell study is even more difficult because to study cells under microscope we have to kill the cells and stain it. However several microscopy may useful to study motility. See table
.
Bacteriphage inside the host cells.
Phage or virus is even smaller than bacteria. Hence it is very difficult to study viral life cycle in side the bacterial host cells. Compound microscope is unable to complete this task. So several microscope listed in table used to study phage inside the host cells.
Bacterial slime layer.
Layer of bacterial cell is made up of micro molecules which is impossible to study with the help of compound microscope.bacterial slime layer can study by microscope listed in table.
Bacterial biofilm on plant leaf
Bacteria infect the plant and creates a white film over a surface. This type of film are observed under compound as well as simple microscope.no complex microscopy is required.
specimen
microscopy
working
advantages
Disadvantages
Motile bacterial cell swimming
Phase contrast
It is an optical microscopy that convert shift of phase. When light passes through the specimen, phase shifted observed under microscope
Good resolution,
No staining required
Required living cells, no color observed
Bright filed
White light is passes through the specimen from dense and light areas of specimen which helps to observe movement of cells across specimen.
Basic set up,
Quick and reliable
Contrast is very low,
Not used for transparent samples
Bacteriophase inside the host cell
SEM (scanning electron microscope)
When an electron beam is focus on the surface, the electron are interact with sample which produces signal and this signals are analyzed.
Best used to study life cycle of viruses, very high resolution
High cost,
Complex set up
TEM(transmission electron microscope)
In this microscopy electron beam is not scanning but transmitted through the specimen.
Very high resolution, can study smaller molecules like protein and viruses
Expensive, required high expertise
Bacterial slime layer
Atomic force microscopy
It is a type of very high resolution microscopy to study atoms or minor surface molecular study of biological specimens
It provides three dimensional surface profile, do not required special sample preparation
Scanning speed is limited, expensive
Electron microscopy
Electron beam is passes through sample which create overall image with the help of electron beam.
High resolution, better result
Expensive, complex set up
Bacterial thin film on plant leaf
Compound microscope
When light passes through stained specimen it is observed under microscope with the help of systemic arrangement of lenses.
Cheap, easy to use, most effective
Required staining steps, resolution is limited
Simple microscope
Very simple set up, only a single lens is used
Can observe cells, no staining required
Very low resolution, not used for smaller molecules.
specimen
microscopy
working
advantages
Disadvantages
Motile bacterial cell swimming
Phase contrast
It is an optical microscopy that convert shift of phase. When light passes through the specimen, phase shifted observed under microscope
Good resolution,
No staining required
Required living cells, no color observed
Bright filed
White light is passes through the specimen from dense and light areas of specimen which helps to observe movement of cells across specimen.
Basic set up,
Quick and reliable
Contrast is very low,
Not used for transparent samples
Bacteriophase inside the host cell
SEM (scanning electron microscope)
When an electron beam is focus on the surface, the electron are interact with sample which produces signal and this signals are analyzed.
Best used to study life cycle of viruses, very high resolution
High cost,
Complex set up
TEM(transmission electron microscope)
In this microscopy electron beam is not scanning but transmitted through the specimen.
Very high resolution, can study smaller molecules like protein and viruses
Expensive, required high expertise
Bacterial slime layer
Atomic force microscopy
It is a type of very high resolution microscopy to study atoms or minor surface molecular study of biological specimens
It provides three dimensional surface profile, do not required special sample preparation
Scanning speed is limited, expensive
Electron microscopy
Electron beam is passes through sample which create overall image with the help of electron beam.
High resolution, better result
Expensive, complex set up
Bacterial thin film on plant leaf
Compound microscope
When light passes through stained specimen it is observed under microscope with the help of systemic arrangement of lenses.
Cheap, easy to use, most effective
Required staining steps, resolution is limited
Simple microscope
Very simple set up, only a single lens is used
Can observe cells, no staining required
Very low resolution, not used for smaller molecules.
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