Question

Suppose a single, linear molecule of double stranded DNA (dsDNA) is amplified by PCR. What is the purpose of PCR amplification?

1) To create multiple copies of the DNA molecule
2) To separate the two strands of DNA
3) To introduce mutations into the DNA sequence
4) To determine the length of the DNA molecule

Answer 1

The purpose of PCR amplification is to create multiple copies of a DNA molecule. It involves cycles of denaturing, annealing, and extension, using Taq polymerase to exponentially amplify the target sequence.

Step-by-step explanation:

The purpose of PCR (Polymerase Chain Reaction) amplification is to create multiple copies of a DNA molecule. Through a series of temperature-controlled cycles—denaturing, annealing, and extension—PCR exponentially amplifies the target DNA sequence. Initially, heat is applied to separate the double-stranded DNA into single strands (denaturing), then the temperature is lowered to allow primers to bind to these strands (annealing). Finally, DNA polymerase synthesizes new strands by adding nucleotides complementary to the original DNA (extension). Taq polymerase is a heat-tolerant enzyme often used in PCR, enabling the cycle to be repeated numerous times without the enzyme denaturing. Each cycle effectively doubles the amount of DNA, and after 30 or so cycles, millions of copies of a specific DNA segment can be produced.