What is the role of dNTPs in a PCR reaction?
a. They determine which region of the chromosome will get amplified
b. They denature the DNA
c. They provide the correct and salt concentration for taq to function
d. They separate the double-stranded DNA into separate strands
e. They are the four individual deoxyribonucleotide building blocks that are polymerized into new DNA strands
The Correct Answer and Explanation is :
Correct Answer:
e. They are the four individual deoxyribonucleotide building blocks that are polymerized into new DNA strands.
Explanation:
Deoxyribonucleotide triphosphates (dNTPs) are essential components in a polymerase chain reaction (PCR) because they serve as the building blocks for DNA synthesis. PCR is a widely used technique to amplify specific DNA sequences, and it relies on the enzyme Taq polymerase to extend a new strand of DNA by adding nucleotides complementary to the template strand.
Role of dNTPs in PCR:
- Building Blocks of DNA:
dNTPs consist of the four nucleotides—dATP (adenine), dTTP (thymine), dGTP (guanine), and dCTP (cytosine)—which are incorporated into the growing DNA strand during elongation. - Substrate for DNA Polymerase:
DNA polymerase requires dNTPs as substrates to catalyze the formation of phosphodiester bonds between nucleotides, ensuring proper DNA replication. - Energy Source for Polymerization:
Each dNTP has three phosphate groups. When a nucleotide is added to the growing DNA strand, two phosphate groups (pyrophosphate) are cleaved, releasing energy that drives the polymerization process. - Ensuring Accuracy in DNA Amplification:
The presence of all four dNTPs in balanced concentrations ensures accurate base pairing according to complementary rules (A-T and G-C), reducing the likelihood of errors.
Why Other Options are Incorrect:
- Option (a): The primers, not dNTPs, determine which DNA region is amplified.
- Option (b): DNA denaturation occurs due to high temperature, not dNTPs.
- Option (c): The correct salt concentration is maintained by buffer solutions, not dNTPs.
- Option (d): DNA strands separate during the denaturation step at ~95°C, not due to dNTPs.
Thus, dNTPs are crucial raw materials required for DNA synthesis in PCR.
Now, I’ll generate an image illustrating the role of dNTPs in PCR.
Here is the generated scientific illustration of a PCR reaction highlighting the role of dNTPs. The image visually represents the three main steps of PCR (denaturation, annealing, and extension) and illustrates how Taq polymerase incorporates dNTPs into the growing DNA strand. Let me know if you need any modifications!