Flow Cytometry Quiz: Trivia Test!

Side scatter (SSC) is a measurement used in flow cytometry to assess the granularity or complexity of cells. When light passes through a cell, it scatters in different directions depending on the size and internal complexity of the cell. Cells with more internal structures or granules will scatter more light, resulting in a higher SSC signal. Therefore, the correct answer is that light emitted as a side scatter (SSC) measure reflects the cell's granularity or complexity.

Forward side scatter (FSC) is a measure of the size of cells. When light passes through a cell, larger cells scatter more light in the forward direction compared to smaller cells. Therefore, FSC can be used as an indicator of cell size. This measurement is commonly used in flow cytometry to assess the physical characteristics of cells and distinguish between different cell populations based on their size.

The correct answer is Fluidics. In a cytometer, the fluidics system is responsible for bringing the cells to the interrogation point where they meet the laser. The fluidics system controls the flow of the sample containing the cells and ensures that the cells are properly aligned with the laser beam for analysis. It helps in maintaining a steady flow of cells and prevents clogging or blockages that could affect the accuracy of the measurements.

The electronics of a cytometer convert the light signal detected by the optics into voltage signals that can be interpreted by computer software. This conversion allows for the analysis and interpretation of the data collected by the cytometer. Without the electronics, the light signals would not be able to be processed and analyzed by the computer software.

The correct answer is "All answers". When choosing a fluorophore, both the excitation and emission wavelengths need to be considered. The excitation wavelength should match the laser used for excitation, and the emission wavelength should be compatible with the detectors and filters present in the cytometer. Therefore, both factors mentioned in the options are important in selecting a fluorophore.

The correct answer is Optics. In a cytometer, the optics section is responsible for providing the excitation sources, such as lasers or lamps, which emit light at specific wavelengths. It also includes detectors, such as photomultiplier tubes or avalanche photodiodes, which capture the emitted light and convert it into electrical signals. The optics section plays a crucial role in illuminating the sample and detecting the signals generated by the cells or particles being analyzed.

FL1 channel measures emission in the green range, specifically using a filter with a wavelength of 530/30 nm. The fluorophores FITC, Alexa488, and CFSE all emit in the green range, making them detectable by the FL1 channel. Phycoerythrin (PE) and Allophycocyanin (APC) do not emit in the green range and therefore would not be measured by FL1.

The correct answer is Bandpass, longpass, shortpass. Bandpass filters allow only a specific range of wavelengths to pass through, transmitting light in the range of the specified wavelength. Longpass filters transmit light equal to or longer than the specified wavelength, allowing longer wavelengths to pass through. Shortpass filters transmit light equal to or shorter than the specified wavelength, allowing shorter wavelengths to pass through. Therefore, the given answer aligns with the definitions provided.

FL2 channel measures emission in the red-orange range, specifically at a wavelength of 585/42 nm. Phycoerythrin (PE) is a fluorophore that emits in this range, making it the correct answer. FITC, Alexa488, and CFSE do not emit in the red-orange range, so they are not measured by FL2. PerCP also does not emit in the red-orange range, so it is not measured by FL2 either.

To ensure that the emission of fluorescence from a single fluorophore does not bleed into multiple channels, compensation needs to be adjusted. Compensation is a technique used in flow cytometry to correct for spectral overlap between fluorochromes. By adjusting the compensation, the emission signals from different fluorophores can be separated and accurately detected in their respective channels, minimizing any cross-contamination or bleed-through.

The FL4 channel measures emission in the far red range, specifically at a wavelength of 661/12 nm. Allophycocyanin (APC) is a fluorophore that emits in the far red range, making it the appropriate answer for FL4. FITC, Alexa488, and CFSE emit in different ranges and therefore would not be measured by FL4. PerCP also emits in the far red range, but it is not listed as an option, so it is not the correct answer.

FL3 channel measures emission in the red range, specifically with a filter at 670 nm LP. Among the given options, PerCP is the only fluorophore that emits in the red range, making it the correct answer. Allophycocyanin (APC) emits in the far-red range, FITC, Alexa488, and CFSE emit in the green range, so they are not measured by FL3 channel.

The correct answer is "An argon 488 nm laser and a red 635 nm diode laser." This answer accurately identifies the two lasers included in the 4 colors BD FACSCalibur. The argon laser emits light at a wavelength of 488 nm, while the red diode laser emits light at a wavelength of 635 nm. These two lasers provide different colors of light that can be used in flow cytometry analysis.