This set of Immunology Multiple Choice Questions & Answers (MCQs) focuses on “Immunofluorescence and Flow Cytometry”.
1. What is another term for Immunofluorescence?
a) Cell imaging
b) Imaging antibodies
c) Fluorophores
d) Antigen imaging
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Explanation: Another term used for immunofluorescence (also denoted as IF) is Cell Imaging. This is because this technique is used for analysis of various applications like evaluation of cells and their culturing along with the study of tissues. This technique comprises of the use of antibodies which help in labelling a target antigen. This is carried out by a fluorescent dye. This technique results in binding or antibody to antigen in direct or indirect ways.
2. Primary type of IF (immunofluorescence) technique uses two antibodies in association with fluorescent dye.
a) True
b) False
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Explanation: Primary Immunofluorescence uses only one antibody with the help of fluorescent dye. In this technique antibody interacts with the antigen. This interaction is initiated by the help of antibody which has a higher affinity to antigen. It targets the antigen and binds to it. This requires a fluorescent dye throughout so that the interaction between antibody and antigen can be observed under a microscope. Primary immunofluorescence is a faster technique as compared to secondary immunofluorescence.
3. Which of the following dye conjugate is termed to be the high-performance conjugate for the use of flow cytometry?
a) Tide FluorTM
b) Tide QuencherTM
c) DyLightTM
d) KLH
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Explanation: Fluorescent conjugates of antibodies are widely used for various tests to be carried out for testing the efficiency and effects of antibodies. One such dye which is considered and is in greater demand is DyLightTM which is used for assay techniques like flow cytometry, ELISA, western blotting as well as microscopy associated with fluorescence. This dye conjugate shows a greater intensity for fluorescence and it becomes easy for scientists to observe the antibody activities.
4. Changes in cell shape, the loss of its structure and cell detachment occurs due to which of the following reason?
a) Irregularity in cell cycle
b) Apoptosis
c) Error in cell’s viability
d) Drop in the level of biological activity of cell
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Explanation: Apoptosis (also termed as programmed cell death) causes characteristic changes in cell shape, loss of structures, cell detachment along with condensation of the cytoplasm, cell shrinkage, phagocytosis of cellular residues and changes in the nuclear envelope. Apoptosis also causes various biochemical changes like breakage of protein structure (termed as proteolysis), denaturation of DNA and irregular levels of ions.
5. Flow cytometry is used to for which cell population?
a) Homogenous population of cells
b) Heterogeneous population of cells
c) Both homogenous and heterogeneous population of cells
d) Heterotopic population of cells
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Explanation: Flow cytometry is principally used for detecting the physical as well as chemical properties of heterogenous population of cells. Cytometry is a technique used for the basic to complex study of cell and with the help of different cytometric techniques, the activities of cells can be tracked. Flow cytometry has an advantage as it differentiates between different cell types and helps in sorting them according to their properties.
6. What are fluorescent molecules and fluorescent dyes also termed as?
a) Fluorophores
b) Molephores
c) Fluorescent molephores
d) Cytochromes
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Explanation: Fluorescent molecules and dyes are called as fluorophores or fluorochromes. They are even sometimes called as fluors. They actively respond to light as compared to other molecules. They are mainly used in conjugation with antibodies as detection reagents in applications such as flow cytometry. They readily absorb and emit light within a particular range of wavelengths which is normally referred to as absorbance range and emission spectra.
7. Which of the following is NOT considered as a parameter for their analysis by Flow Cytometry?
a) Functional analysis
b) Cell viability
c) Clonality
d) Cell cycle analysis
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Explanation: Flow cytometry is a process which is specifically used for the analysis and detection of physicality as well as functionality of cells. This method helps to analyse several parameters of a cell simultaneously some of them being cell function, their viability, apoptosis/necrosis as well as the cell cycle.
8. Which of the following is NOT a component of flow cytometer?
a) Fluidics system
b) Optical system
c) Electronic system
d) Chemical system
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Explanation: Flow cytometer is an instrument used to carry out flow cytometry. This device is designed in a way so that it includes fluidics, optics as well as electronic components. There is no such system or component that supports chemical analysis. Out of the three main components, fluidics component helps in analysis of rate of flow of the cell (in order to check viability). The optical component includes all lenses and light sources necessary for observation of cell and its physical properties. Lastly, the electronic component manages the entire working of cytometer.
9. What is physiological buffer used in flow cytometer called as?
a) Sheath fluid
b) Fluorescent fluid
c) Chemical fluid
d) Stream fluid
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Explanation: The most important part of using a flow cytometer lies in the fluid that is involved which acts as a physiological buffer. One such buffer used is the sheath fluid. This fluid is at its perfect viscosity in order to direct the cells and maintain their movement in the cytometer. The cell that has to be studied is surrounded completely by this sheath fluid.
10. Which of the following is the most important Fluorescent Protein used in Flow Cytometry?
a) FITC
b) PE
c) GFP
d) APC
View Answer
Explanation: There are a number of fluorescent molecules that play a very important role in Flow cytometry. These molecules absorb as well as emit the light in optimal levels. The fluorescent dyes are categorised in three major types namely Single Dyes, Tandem Dyes and Fluorescent Proteins. GFP (green fluorescent protein) is the most important fluorescent protein for understanding the protein expression of the cells. It is also considered to be the principal tool as it is used in various cases. Other fluorescent proteins include McCherry and YFP (yellow fluorescent protein). On the other hand, FITC, PE, APC are all the types of Single Dyes. These dyes use great photostability and emit bright fluorescence.
Sanfoundry Global Education & Learning Series – Immunology.
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