SCYM Sample Preparation & Staining Techniques

Question 1

Why is sample preparation crucial in flow cytometry?

Accepted Answer

To ensure reliable measurements

Answer

Sample preparation is critical in flow cytometry to ensure reliable and accurate measurements. Proper preparation, including steps like cell isolation, washing, and filtration, removes debris and cell clumps that can clog the instrument or interfere with data. This meticulous process ensures that individual cells are presented optimally for analysis, minimizing background noise and leading to high-quality, reproducible results.

Question 2

Which reagent is used to fix cells for flow cytometry?

Accepted Answer

Formaldehyde

Answer

Formaldehyde (or paraformaldehyde) is a commonly used reagent to fix cells for flow cytometry. Fixation works by cross-linking proteins, which preserves the cellular structure and antigenicity, making cells more stable for subsequent staining and analysis. This step is particularly important for intracellular staining or when samples need to be stored before analysis, maintaining cell integrity and marker expression.

Question 3

What is the function of staining buffers?

Accepted Answer

Prevent non-specific binding

Answer

Staining buffers are used in flow cytometry to prevent non-specific binding of antibodies or fluorochromes to cellular components. These buffers often contain proteins like BSA or FBS, which block reactive sites on the cells. By minimizing non-specific interactions, staining buffers reduce background noise and enhance the specificity of the fluorescent signal, leading to clearer and more accurate detection of target antigens.

Question 4

What is a fluorochrome?

Accepted Answer

Fluorescent dye

Answer

A fluorochrome is a fluorescent dye, a chemical compound that absorbs light at a specific wavelength (excitation) and then re-emits light at a longer, different wavelength (emission). In flow cytometry, fluorochromes are conjugated to antibodies or other probes to specifically label cellular components. Their ability to emit detectable light upon laser excitation allows for the identification, quantification, and differentiation of various cell populations.

Question 5

Why must cells be filtered before analysis?

Accepted Answer

Remove clumps and debris

Answer

Cells must be filtered before flow cytometry analysis to remove clumps and debris from the sample. Cell clumps can be misinterpreted as single, larger cells, leading to erroneous data, while debris can interfere with light scatter and fluorescence measurements. Filtration ensures a clean, single-cell suspension, which is essential for preventing instrument clogging and obtaining accurate, reliable single-cell data.

(SCYM) Specialist in Cytometry Practice Test

(SCYM) Specialist in Cytometry Practice Test

SCYM Sample Preparation & Staining Techniques