Question

What molecules are used as the building blocks of the new DNA strand in DNA replication (human body) versus PCR?

Answer 1

The molecules that are used in DNA replication are as follows:

• The new DNA strand will be formed as the complementary of the previous DNA strand acting as the template since DNA replication is semi-conservative.
• Enzymes like DNA polymerase DNA primase, DNA helicase, DNA ligase, and topoisomerase is needed for the new DNA.
• The buliding blocks of the new DNA strand are the nucleotides made of three parts: a phosphate group, a sugar group and one of four types of nitrogen bases (thymine, cytosine, adenine and guanine).

The molecules that are used by a PCR includes the following:

• The DNA sample acting as the template for the new DNA.
• 4 deoxyribonucleoside triphosphates which are adenosine triphosphate, guanosine triphosphate, thymidine triphosphate and cytidine triphosphate (these are often referred to as the building blocks of the new DNA strand).
• Taq Polymerase, or similar polymerase enzyme, that can operate at high temperatures.
• 2 Primers (forward and reverse) for starting the process of replication.
• Buffers and salts for creating the correct conditions for the enzyme to function.

Thus in DNA replication in human body and PCR both make use of the 4 nucleotides or 4 deoxyribonucleoside triphosphates for the new DNA strand. DNA replication in body uses DNA polymerase as a major enzyme while PCR often uses Taq Polymerase or any other similar enzymes (these will mostly have a much shorter half-life than the natural DNA polymerase). DNA replication in body occurs at body temperature (37C in humans) while PCR reaction utilizes temperature cycles (with extremes of 70-90C) to cause denaturation and annealing of DNA strands.