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  • In a ploymerase chain reaction , temprature required for the steps  1) Denaturation,  2) Annealing and  3) Extension are respectively <div clas

In a ploymerase chain reaction , temprature required for the steps 

1) Denaturation, 

2) Annealing and 

3) Extension are respectively 

Option: 1

1) 94oC    2) 40oC    3) 72oC 


Option: 2

1) 40oC    2) 72oC    3) 94oC 


Option: 3

1) 94oC    2) 72oC    3) 40oC 


Option: 4

1) 72oC    2) 94oC    3) 40oC 


Answers (1)

best_answer

As we have learned

At the start of PCR, the DNA from which a segment is to be amplified, an excess of the two primer molecules, the four deoxynucleoside triphosphates and the DNA polymerase are mixed in the reaction mixture that has appropriate quantities of Mg 
2+
 . 
The reaction mixture is first heated to a temperature between 90−98 degree celcius (commonly 94 degree celcius) that ensures DNA denaturation. Every single strand of the target DNA then acts as a template for DNA synthesis. This is the denaturation step. The duration of this step in the first cycle of PCR is usually 2 min at  94 degree celcius. 
The mixture is now cooled to a temperature (generally 40−60 degree celcius ) that permits annealing of the primer to the complementary sequences in the DNA. This step is called annealing. The duration of the annealing step is usually 1 min.
The primers are extended towards each other so that the DNA segment lying between the two primers is copied, this is ensured by employing primers complementary to the 3': ends of the segment to be amplified. The duration of primer extension is usually 2 min at 72  degree celcius

Hence, the correct option is (a).

 

 

 

Posted by

Sanket Gandhi

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