Which molecular method uses fluorescent probes to evaluate genes and/or DNA sequences on chromosomes?

Fluorescence in situ hybridization (FISH) is a powerful molecular technique that utilizes fluorescent probes to detect and localize specific DNA sequences on chromosomes. This method enables visualization of the genetic material within the context of the cellular structure, allowing for the assessment of chromosomal abnormalities, gene mapping, and detection of specific genes in their natural chromosomal context.

The use of fluorescent dyes means that when the probes bind to the target DNA sequences, they emit light at particular wavelengths, which can be observed under a fluorescence microscope. This makes it possible to pinpoint the location of specific genes or DNA sequences directly on chromosomes, facilitating detailed genomic analyses.

In contrast, techniques like polymerase chain reaction (PCR) and real-time PCR are primarily used for amplifying and quantifying DNA but do not provide spatial information about where genes are located on chromosomes. Reverse transcription PCR is used specifically to convert RNA into DNA and subsequently amplify it, without providing chromosomal localization.

Therefore, the method that specifically employs fluorescent probes to evaluate genes and DNA sequences on chromosomes is FISH, making it the correct answer.