What is the Difference Between PCR and DNA Sequencing?

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PCR (Polymerase Chain Reaction) and DNA sequencing are two distinct laboratory techniques that use the same starting materials, but they serve different purposes and cannot replace each other.

PCR:

  • Amplifies specific DNA sequences, creating millions of copies of a DNA sample.
  • Requires two primers facing each other to start their function.
  • Primers are short DNA samples, and DNA polymerase is another reagent required for the process.
  • Used in the early stages of processing DNA for sequencing and for detecting the presence of specific DNA sequences in tiny samples.

DNA Sequencing (e.g., Sanger Sequencing):

  • Determines the precise nucleotide sequence in a given DNA fragment.
  • Requires only one primer reading the sequence in one direction.
  • Used to determine the correct sequences of the bases in DNA for medical, research, or criminal applications.

In summary, PCR is used to amplify specific DNA sequences, while DNA sequencing is used to determine the order of nucleotides in a DNA molecule. PCR can be followed by DNA sequencing to create enough copies of the DNA to be sequenced.

Comparative Table: PCR vs DNA Sequencing

Here is a table comparing the differences between PCR and DNA sequencing:

Feature PCR (Polymerase Chain Reaction) DNA Sequencing
Purpose Amplifies specific DNA sequences, creating thousands to millions of copies of a particular DNA fragment. Determines the precise order of nucleotides in a given DNA fragment.
Technique DNA amplification. Determining the sequence of bases in DNA.
Outcome Thousands to millions of copies of the target DNA region are produced. The correct order of the bases in a particular DNA fragment is determined.
Involvement of ddNTPs PCR does not require ddNTPs, it uses dNTPs. DNA sequencing requires ddNTPs (Dideoxynucleotide triphosphates) to terminate strand formation.
Involvement in DNA Sequencing PCR is often used in the process of DNA sequencing to create sufficient quantity of DNA for sequencing. DNA sequencing is the final step in determining the precise order of nucleotides in a given DNA fragment.

In summary, PCR is used to amplify specific DNA sequences, creating a large number of copies of a particular DNA fragment. On the other hand, DNA sequencing is a technique used to determine the order of nucleotides in a DNA molecule. PCR is often used in the process of DNA sequencing, but they serve different purposes and use different methods to achieve their respective goals.