The Core Process of DNA Sequencing
DNA sequencing is a laboratory technique used to determine the precise order of nucleotides (adenine, guanine, cytosine, and thymine) within a DNA molecule. This ordered sequence, often referred to as a DNA "read," carries the genetic instructions for building and operating an organism, much like letters form words in a book of life.
Key Principles and Methods
The earliest widely adopted method, Sanger sequencing, relies on synthesizing new DNA strands in a controlled reaction, terminating them at specific nucleotides to reveal the sequence. More advanced Next-Generation Sequencing (NGS) technologies, such as Illumina sequencing, can perform millions of sequencing reactions simultaneously, enabling rapid and high-throughput analysis of entire genomes.
A Practical Example
For instance, if scientists suspect a patient has a genetic disorder, they might extract DNA from a blood sample. After amplifying specific target genes using techniques like PCR, these genes are then sequenced. Comparing the patient's gene sequence to a healthy reference sequence can pinpoint mutations responsible for the disease, guiding diagnosis and treatment.
Importance and Applications
DNA sequencing is indispensable in diverse fields, from clinical medicine to evolutionary biology and agriculture. In healthcare, it aids in diagnosing genetic diseases, identifying infectious pathogens, and developing personalized treatments. It also drives genomic research, forensic science, and the engineering of new biological products like improved crops or pharmaceuticals.