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Over the past decades, a variety of scientific techniques have been developed that have vastly changed the ability of scientists to analyze, manipulate, and understand DNA. The techniques have been critical in many realms of research and form the foundation on how humans have begun to interpret our genetics.
Electrophoresis
Electrophoresis is a technique that uses an electrical field to separate DNA (or other molecules) in a sample by their charge and their size. The sample is placed in a gel matrix within a solution that an electrical current is run through. This forces the molecules in the sample to move through the gel, with negatively charged molecules, like DNA, moving towards the positive electrode. Smaller molecules or segments of DNA are able to move further through the gel in a given amount of time than larger ones. The separation of the molecules can be visualized using stains and dyes. This allows scientists to inspect the size, purity, and/or composition of molecules in a sample. With DNA, it allows scientists to separate segments of different base pair lengths. This technique is very commonly used in genetic research and diagnostics.
Polymerase Chain Reaction (PCR)
Polymerase Chain Reaction (PCR) is used to copy and replicate (or amplify) a specific segment of DNA. In this technique, scientists change the environmental conditions around the DNA to force this to happen. There are three main steps that are repeated in cycles. The first is denaturation, where the strands are separated by increasing the environmental temperature. The second is annealing, where primers specific to the target sequence are added so that they can bind to the unwound DNA. The third is extension, where the DNA polymerase synthesizes a new copy of the DNA. PCR is widely used in molecular biology for cloning, gene analysis, and forensic science. By increasing the amount of DNA that is present, scientists are able to do additional analysis, identification, and experiments. This is often a precursor to other biotechnology techniques.
Bacterial Transformation
Bacterial transformation is a naturally occurring process in which bacteria take up DNA from their environment and incorporate it into their own genome. This process can be manipulated and encouraged in the laboratory as a way of getting desired DNA into bacteria. This desired DNA may cause the bacteria to produce specific proteins, provide antibiotic resistance, or produce other traits that are useful for research.
DNA Sequencing
DNA sequencing is a technique that determines the exact sequence of nucleotides (adenine, thymine, cytosine, and guanine) in a DNA molecule. There are several different methods with varying accuracy and speed. The ability to sequence large lengths of DNA has increased dramatically in recent history. This has allowed scientists to do whole-genome sequencing of many complex organisms. DNA sequencing is a powerful tool used in a variety of applications including genomics, medicine, and biotechnology as a way of understanding genetic information and variations. One of the earlier projects related to DNA sequencing was the Human Genome Project. This project, started in 1990, had the goal of identifying and sequencing the over 20,000 genes in the human genome. The information gained through this project has be revolutionary in understanding diseases, advancing medicine, and understanding human biology.
