Question

1. Microscope Question: What type of microscopy would you use for each situation situation and why and how does it work

1. Routine examination of cheek cells in a classroom setting
2. Tracking the localization of a transgenic protein from DNA transformed into the cell.
3. Examining and generating 3D images of very small ultrastructures of cells
4. Examining a specimen that is visible to an ordinary light microscope but in a specimen that is transparent without staining
5. You wish to internally observe a complex living mass of cells without any physical dissection.
6. For confocal microscopy describe the different components light interacts with from laser to detector.

Answer 1

1. For the routine examination of the cheek cells, the microscopic technique that can be used is- LIGHT MICROSPCOPY, which uses light(from natural or artificial source) to light up the components of the cells that are stained with appropriate stains. The stains create a contrast between the various organelles inside the cell, so they are easily visible. The cells can be easily viewed by Bright field Microscope, which uses the principle of Light microscopy.

2. For gtracking the localization of a transgenic protein , the microscopy technique that can be used is Fluorescence microscopy. The gene of the protein can be tagged with the gene of a fluorescent protein(eg- GFP) to produce a fusion protein. In this way, when the protein will be synthesized, the protein will have the intrinsic fluorescence capacity. This protein can be tracked by using Fluorescence microscopy, where we have to use a specific filter for the colour of the light that the protein will emit.

3. Scanning electron microspcopy can be used to construct a 3d image of the ultrastructure of the cells. The SEM uses Electrons to get hit onto the sample, and based on the scattering of the electrons after the bombardment with the sample, the image is processed and created into a 3D model.

4. In the case of transparent specimens, the PHASE CONTRAST MICROSCOPY can be used, which is actually based on changing the phase of the light passing through a transparent specimen and then according to the changes in the phases of the light(while passing through the specimen structures), the image is formed.

5. Observation, without physical dissection of the specimen can be done bu using Confocal microscopy.

6. In the confocal microscopy, the light is emitted by the laser.

a. After emission, the light interacts with the dichoric mirror—which are the mirrors that can have different reflection properties at different wavelengths.

b. After being reflected by the mirror, the light passes through the objective lens—which is the lens that is placed close to the specimen and that is used to converge the light to the specimen.

c. The light after being reflected from the specimen, again passes back through the objective lens and dichoric lens(this time the light passes through without getting reflected).

d. The light passing through the dichoric lens are of two types- out of focus and in focus light.

e. The in focus light passes through the Emission pinhole, whichi is the last passage before reaching the detector.

f. Then ultimately the light recheas the detector, which actually converts the light energy to the electrical energy and the image is formed.