The Taq polymerase enzyme is obtained from

1. Thiobacillus ferroxidans

2. Bacillus subtilis

3. Pseudomonas subtilis

4. Thermus aquaticus

Which of the following statements is incorrect with respect to polymerase chain reaction?

(1) Repeated amplification is achieved by the use of thermostable DNA polymerase

(2) Thermostable DNA polymerase is isolated from a bacterium, Thermus aquaticus

(3) Each cycle in PCR has three steps, first is primer annealing, second is denaturation and third is extension of primers

(4) In polymerase chain reaction, multiple copies of gene of interest are synthesized in vitro using two sets of primers and enzyme DNA polymerase

The figure below shows three steps (A, B, C) of polymersase chain reaction (PCR). Select the correct identification together with what it represents

1. B - Denaturation at a temperature of about 98°C separating the two DNA strands

2. A - Denaturation at a temperature of about 60°C

3. C - Extension in the presence of heat stable DNA polymerase

4. A - Annealing with two sets of primer

Select the incorrect statement.

1. Separation of DNA fragments occurs based on their size in agarose gel.

2. Blue-white selection involves insertional inactivation of β-galactosidase.

3. Treatment with ice-cold calcium can enhance efficiency of transformation in host cells.

4. Extension step during PCR is based on thermolabile nature of Taq polymerase.