Why do we use the flourscent dye in DNA sequencing, what does it show?
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Fluorescent dyes are used in DNA sequencing to label the DNA fragments. These dyes emit fluorescence when excited by a specific wavelength of light. The use of fluorescent dyes allows scientists to visualize and track the DNA fragments during the sequencing process by detecting their emitted fluorescence.
In DNA sequencing, the DNA molecule is fragmented into smaller pieces, and each fragment is labeled with a unique fluorescent dye. These dyes are typically attached to the DNA fragments during the DNA amplification step using a technique called PCR (polymerase chain reaction). Different dyes are used to label the DNA fragments at specific positions, known as terminators.
During the sequencing process, the DNA fragments are run through a capillary electrophoresis instrument. This instrument separates the DNA fragments based on their size and detects the emitted fluorescence from the labeled dye as the fragments pass through the capillary. The instrument measures the color and intensity of the fluorescent signal, which represents the sequence information of the DNA.
By using different fluorescent dyes at specific positions, the DNA sequencing instrument can identify the order in which the nucleotides (A, C, G, T) occur in the DNA fragment. Each dye corresponds to one of the nucleotides, and the instrument reads the fluorescent signal to determine the DNA sequence.
In summary, the fluorescent dye used in DNA sequencing allows scientists to visualize and track the DNA fragments during the sequencing process, enabling the identification of the DNA sequence based on the emitted fluorescence from each labeled fragment.