Chat with AIExam 4: Culturing and Visualizing Cells
Describe how a Förster resonance energy-transfer (FRET)biosensor like cameleon,which consists of CFP linked to YFP by the protein calmodulin,can detect local changes in calcium ion concentration.For your information,CFP excites at 440 nm and emits at 480 nm,whereas YFP emits at 535 nm.
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VerifiedBasically,if calcium is absent and the cameleon construct is excited by UV light at 440 nm,there is emission of energy at 480 nm,but because the distance between CFP and YFP is greater than 10 nm,the energy cannot be transferred to YFP and hence there is no detection of light at 535 nm.In the presence of calcium ions,however,calmodulin undergoes a conformational change,which brings CFP in close proximity to YFP.When CFP is excited with UV light at 440 nm,the energy is transferred to YFP,allowing it to fluoresce and be detected at 535 nm.
You are studying lamins and use an antibody method to follow their expression and subcellular localization at the electron microscope level.What process would you use to find these proteins in the bacteria E.coli?
(38) VerifiedNormally,antibody labeling can be used in tandem with electron microscopy to visualize proteins in thin sections.Cells are lightly fixed to avoid denaturing the epitopes on the desired protein and,after freezing,the tissue is sectioned at very low temperature.The tissue is thawed and a specific antibody to the desired protein is applied as in immunofluorescence microscopy.To detect the antibody,however,the tissue is incubated with electron-dense gold particles attached to protein A,a bacterial protein that binds the Fc segment of all antibodies.These gold particles are seen at the level of the electron microscope;however,you would not be able to see lamins in E.coli because bacteria do not contain membrane-bounded organelles and lamins are a component of the nuclear envelope.
Fluorescence microscopy of cells that are labeled with a green fluorescent antibody against microtubules (a cytoskeletal component)differs from cells expressing green fluorescent protein (GFP)tagged to beta tubulin (a component of microtubules)in all the following ways EXCEPT:
(36) VerifiedD
Although many types of vesicles are similar in size and density,it is possible to isolate specific types of vesicles through the use of:
(30) Which one of the following is the best technique/approach to allow you to localize catalase in peroxisomes?
(45) Proteomic studies allow for the identification of all proteins within an organelle,assuming the organelle can be purified sufficiently well.Proteomic analyses of mitochondria from different cell types revealed what interesting finding?
(35) Centrifugation of homogenized tissue from a mouse liver at 15,000 × g for 5 minutes will pellet:
(33) The purpose of treating tissue from an embryonic chick with trypsin and EDTA when generating a primary cell culture is to:
(39) How does the wavelength of the light used to illuminate a specimen affect the ability to resolve objects within the specimen?
(35) A small tumor is excised from a patient's body.The pathologist wants to examine the number,size,and arrangement of cells within the tumor.The best technique to use would be:
(38) When studying a new protein,it is useful to generate an antibody against it to tag it in experiments designed to study its function and localization.Which of the following is NOT a step needed to generate this new antibody?
(36) Rank the following organelles in terms of most dense to least dense:
i.mitochondria II.peroxisomes III.lysosomes
(30) Which of the following could be used to visualize subcellular structure in living cells?
(32) Separation of most blood cells is difficult,if not impossible,to achieve because they have similar properties and/or densities.What procedure is 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?
(36) Epithelial cells have distinct surfaces.Which of these surfaces tends to be involved in secreting proteins out of the cell and into the bloodstream?
(39) The phenomenon in which a chemical absorbs light at one wavelength and emits it at a specific and longer wavelength is called:
(37) If a cellular homogenate were subjected to differential centrifugation,which of the following would be expected to pellet first?
(30) The disruption of a cell is necessary to release its organelles and contents for subsequent isolation.One method,called _____,uses ultrahigh-frequency sound to disrupt the cell plasma membrane.
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