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Question
Which of the following enzymes are used in PCR?
Which of the following enzymes are used in PCR?
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Solution
The correct option is D Taq polymerase
PCR or polymerase chain reaction is a technique used in molecular biology to create several copies of a certain DNA segment.
The PCR involves three major cyclic reactions:
- Denaturation: The reaction mixture containing DNA is heated to 94-96℃. This breaks the hydrogen bonds between the two strands of DNA and converts it into a single-stranded DNA. The single strands now act as a template for the production of new strands of DNA.
- Annealing: Here, the single-strand sequences of DNA called primers bind to their complementary sequences on the template DNA. They serve as the starting point for the synthesis of DNA. The reaction temperature is lowered to 55-65℃.
- Extension: The bases are added to the 3' end of the primer by the Taq polymerase enzyme. This elongates the DNA in the 5' to 3' direction. The temperature is raised to 72℃ for this step.
Taq polymerase is obtained from Thermus aquaticus which is an archaebacteria that can survive in high temperatures. Due to this, their enzymes are capable of working in unusually high temperatures and perfectly suitable for PCR which involves such high temperatures in its denaturation step.
Ribozymes are RNA enzymes catalysing the bond formation between two adjacent amino acids during protein synthesis (translation). Examples include 28S rRNA.
Helicase enzymes bind to the DNA molecule during replication and separate the double stranded DNA. This allows access to other enzymes which can then help in further processes like replication of DNA.
Primer is a short DNA strand (oligonucleotide) used to initiate the synthesis of DNA. They bind to the complementary sequence on DNA template to provide free 3' OH on which DNA polymerase enzyme can add on nucleotides.
PCR or polymerase chain reaction is a technique used in molecular biology to create several copies of a certain DNA segment.
The PCR involves three major cyclic reactions:
- Denaturation: The reaction mixture containing DNA is heated to 94-96℃. This breaks the hydrogen bonds between the two strands of DNA and converts it into a single-stranded DNA. The single strands now act as a template for the production of new strands of DNA.
- Annealing: Here, the single-strand sequences of DNA called primers bind to their complementary sequences on the template DNA. They serve as the starting point for the synthesis of DNA. The reaction temperature is lowered to 55-65℃.
- Extension: The bases are added to the 3' end of the primer by the Taq polymerase enzyme. This elongates the DNA in the 5' to 3' direction. The temperature is raised to 72℃ for this step.
Taq polymerase is obtained from Thermus aquaticus which is an archaebacteria that can survive in high temperatures. Due to this, their enzymes are capable of working in unusually high temperatures and perfectly suitable for PCR which involves such high temperatures in its denaturation step.
Ribozymes are RNA enzymes catalysing the bond formation between two adjacent amino acids during protein synthesis (translation). Examples include 28S rRNA.
Helicase enzymes bind to the DNA molecule during replication and separate the double stranded DNA. This allows access to other enzymes which can then help in further processes like replication of DNA.
Primer is a short DNA strand (oligonucleotide) used to initiate the synthesis of DNA. They bind to the complementary sequence on DNA template to provide free 3' OH on which DNA polymerase enzyme can add on nucleotides.
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