Which type of probe in FISH is used to identify specific regions of chromosomes?

In fluorescence in situ hybridization (FISH), the use of single-copy or gene-specific probes is particularly effective for identifying specific regions of chromosomes. These probes are designed to hybridize to unique sequences of DNA that correspond to particular genes or regions of interest, allowing for precise localization and visualization within a chromosome under a fluorescence microscope.

Single-copy or gene-specific probes bind strongly to their target sequences, enabling researchers to determine the presence, absence, or alterations of specific genes associated with various conditions or diseases. This specificity is crucial when studying genetic anomalies, such as deletions or duplications, which can have significant implications for diagnosis and treatment in molecular diagnostics.

The other types of probes serve different purposes. Alpha satellite probes are primarily used to identify centromeric regions, while dual-color probes allow for the concurrent visualization of two different targets but do not specifically focus on individual gene regions. Painting probes cover large segments of chromosomes and provide a broad overview of chromosomal structure but do not pinpoint specific genes. Thus, the selected answer accurately reflects the function and application of single-copy or gene-specific probes in the context of FISH.