Amplify DNA with Polymerase Chain Reaction (PCR): A Technique for Generating Millions of Identical DNA Copies

You have three copies of a particular DNA molecule. What technique would you use to make more copies of the molecule?

To make more copies of a DNA molecule, you can use a technique called Polymerase Chain Reaction (PCR)

To make more copies of a DNA molecule, you can use a technique called Polymerase Chain Reaction (PCR). PCR allows for the amplification of specific DNA sequences, generating millions to billions of identical copies of the target DNA.

The steps involved in PCR are as follows:

1. Denaturation: The DNA sample is heated to a high temperature (typically around 94 to 98 degrees Celsius) to separate the double-stranded DNA molecule into two single strands. This step breaks the hydrogen bonds between the complementary bases, resulting in the complete denaturation of the DNA.

2. Annealing: The temperature is then lowered to around 50 to 65 degrees Celsius, allowing short DNA primers to bind specifically to the complementary sequences on each single-stranded DNA template. These primers are typically 15-25 nucleotides long and flank the target DNA sequence of interest.

3. Extension: The temperature is raised to about 72 degrees Celsius, and a heat-stable DNA polymerase enzyme, such as Taq polymerase, synthesizes new DNA strands starting from the primers. The polymerase incorporates free nucleotides into the growing DNA chain, adding complementary bases to each single-stranded template.

These three steps (denaturation, annealing, and extension) constitute one cycle of PCR. Multiple cycles of heating and cooling are then repeated (typically 20-35 cycles), leading to an exponential increase in the number of DNA molecules. Each cycle effectively doubles the number of copies of the target DNA sequence.

In your specific scenario, where you have three copies of a DNA molecule, PCR could be used to amplify these molecules and produce millions of identical copies.

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