d. deconvolution microscopy 14. How does the wavelength of the light used to ill
ID: 190127 • Letter: D
Question
d. deconvolution microscopy 14. How does the wavelength of the light used to illuminate a specimen affect the ability to resolve objects within the specimen? 15. Separation of most blood cells is difficult, if not impossible, to achieve because they have similar properties and/or densities. What are the two procedures that can be used to separate T-cells of the immune system from the many other different types of white blood cells or spleen cells? What feature of the T-cell facilitates the isolation protocol? 16. Rough endoplasmic reticulum can be separated from smooth endoplasmic reticulum by differential centrifugation. What is the basis for this fractionation? Page 3 of 3Explanation / Answer
14. The resolving power of a microscope depends on numerous factors, wavelength is one of them. Following formula explains the relation between resolving power and the wavelength.
Resolving power d = 0.61/NA
Where, NA is the numerical aperture. Numerical aperture is n sin , where is the angle formed between the eye piece and the objective.
Thus, wavelength is directly proportional to the resolving power.
Staining improves the overall contrast of the specimen by allowing some wavelengths of light to pass through it and retaining others, thus enhancing the overall contrast which eases the study of distinguishing features in the specimen.
15. Ficoll-paque density gradient separation is used for the separation of T cells from rest of the cells.
Procedure – it is performed by adding diluted whole blood in buffer like HBSS or PBS. Then spinned over a Ficoll gradient, majority of granulocytes separate at the bottom of the tube along with red blood cells. The wbcs remain in middle of the tube appearing as white ring which is also known as buffy coat. Plasma form the top layer. The buffy coat can be collected to obtain lymphocytes and monocytes. Lastly a magnetic bead separation can also be done followed by positive selections to carry out additional isolation.
16. During centrifugation, the microsomes (small vesicles) formed from the Rough ER contains ribosomes and the microsomes formed from the Smooth ER does not contain the ribosomes. The presence of ribosomes in the microsomes add some mass, which separates the RER and SER.
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