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Enzyme required for polymerase chain reaction (PCR) is
Enzyme required for polymerase chain reaction (PCR) is
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Solution
The correct option is C Taq polymerase
Polymerase chain reaction (PCR) is a technique used for the in vitro amplification of the DNA fragments or gene of interest to create multiple copies.
Steps involved in PCR is as follows:
- Denaturation - In this step separation of the two strands of double stranded DNA done by application of heat at 94−95∘C.
- Annealing - This step involves the hybridisation of the primers with specific sequences of each of the strands of the template DNA. Primers are small oligonucleotides up to 18 - 24 nucleotides long synthesised chemically. This process is carried out at 50−56∘C.
- Extension or synthesis - In this step the Taq DNA polymerase synthesises DNA by adding dNTPs (deoxyribonucleotides) to the free ends of the primers. The extension of DNA is carried out at 72∘C. This helps in synthesising complementary strands.
RNA polymerase adds nucleotides to form a long chain of RNA through phosphodiester bonds. Since PCR involves amplification of DNA not RNA this enzyme is not used. RNA can be amplified using reverse - transcriptase PCR (RT - PCR).
Ribonuclease enzyme removes the nucleotides from the RNA chain by breaking the phosphodiester bonds. Since PCR involves amplification of DNA this enzyme is not used.
Taq polymerase is a thermostable enzyme obtained from bacterium Thermus aquaticus. It is used in PCR technique to withstand variable temperature conditions. Taq DNA polymerase synthesises DNA by adding dNTPs to the free ends of the primers in the extension step of PCR. This helps in synthesising complementary strands.
Endonuclease is an enzyme that cleaves DNA at any point within the DNA strand but not at the ends. For example, restriction endonucleases are used in genetic engineering to cleave the vector DNA and DNA of interest. They are not used in PCR.
Hence the correct option is
c. Taq polymerase
Polymerase chain reaction (PCR) is a technique used for the in vitro amplification of the DNA fragments or gene of interest to create multiple copies.
Steps involved in PCR is as follows:
- Denaturation - In this step separation of the two strands of double stranded DNA done by application of heat at 94−95∘C.
- Annealing - This step involves the hybridisation of the primers with specific sequences of each of the strands of the template DNA. Primers are small oligonucleotides up to 18 - 24 nucleotides long synthesised chemically. This process is carried out at 50−56∘C.
- Extension or synthesis - In this step the Taq DNA polymerase synthesises DNA by adding dNTPs (deoxyribonucleotides) to the free ends of the primers. The extension of DNA is carried out at 72∘C. This helps in synthesising complementary strands.
Ribonuclease enzyme removes the nucleotides from the RNA chain by breaking the phosphodiester bonds. Since PCR involves amplification of DNA this enzyme is not used.
Taq polymerase is a thermostable enzyme obtained from bacterium Thermus aquaticus. It is used in PCR technique to withstand variable temperature conditions. Taq DNA polymerase synthesises DNA by adding dNTPs to the free ends of the primers in the extension step of PCR. This helps in synthesising complementary strands.
Endonuclease is an enzyme that cleaves DNA at any point within the DNA strand but not at the ends. For example, restriction endonucleases are used in genetic engineering to cleave the vector DNA and DNA of interest. They are not used in PCR.
Hence the correct option is
c. Taq polymerase
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