Biology Major Field Test Practice 2025 – Comprehensive All-in-One Guide to Exam Success!

The Sanger method, also known as chain termination sequencing, is distinguished by its use of chain-terminating nucleotides, which are essential to the process. During sequencing, normal deoxynucleotide triphosphates (dNTPs) are incorporated into a growing DNA strand, but the addition of modified nucleotides called dideoxynucleotides (ddNTPs) halts the elongation of the DNA chain. This results in fragments of varying lengths that can then be separated by size through capillary electrophoresis or gel electrophoresis. The terminators prevent further addition of nucleotides once they are incorporated, allowing specific sequences to be identified based on the length of each fragment produced.

The other options, while related to sequencing techniques in general, do not accurately describe the hallmark feature of the Sanger method. For example, the method does not utilize RNA templates; its focus is on DNA. Fluorescent labeling is a feature of some modern sequencing methods but is not a defining characteristic of Sanger sequencing. Lastly, while the Sanger method is indeed more suited for smaller DNA fragments compared to next-generation sequencing methods (which can handle larger volumes of data), it is capable of sequencing longer fragments than