PCR Cycle

Q. Which of the following shows the correct sequence of steps in polymerase chain reaction (PCR)?

1. Denaturation, extension and annealing
2. Annealing, extension and denaturation
3. Extension, denaturation and annealing
4. Denaturation, annealing and extension

Q. The correct order of steps in Polymerase Chain Reaction (PCR) is

1. Denaturation, Extension, Annealing
2. Anealing, Extension, Denaturation
3. Extension, Denaturation, Annealing
4. Denaturation, Annealing, Extension

Q. Analyse the events during every stage of the cell cycle and notice how the following two parameters change:

Q. Palaeontologists unearthed a human skull during excavation. A small fragment of scalp tissue was still attached to it. Only little DNA could be extracted from it. If the genes of the ancient man need to be analysed, the best way of getting sufficient amount of DNA from this extract is:

1. By hybridizing the DNA with the DNA probe
2. By subjecting the DNA into polymerase chain reaction
3. By subjecting the DNA into gel electrophoresis
4. By treating the DNA with restriction endonucleases

Q. A biology student is performing PCR for the first time. She adds the right DNA fragments and its corresponding primers. She also adds DNA polymerase and free nucleotides. The reaction mixture is kept in a water bath that measures ${37}^{\circ }C$. But DNA amplification does not occur. Why?

1. Thermocycler was not used to maintain temperatures required for PCR
2. DNA primers got denatured at ${37}^{\circ }C$
3. She added DNA polymerase instead of RNA polymerase
4. Not enough DNA Fragments were available for the DNA polymerase to act on.

Q. The instrument used for PCR is called __.

Q. The thermostable enzymes, ‘Taq’ and ‘Pfu’, isolated from thermophilic bacteria are

1. RNA polymerases
2. DNA polymerases
3. restriction endonucleases
4. DNA ligases

Q. Which one is a true statement regarding DNA polymerase

1. It is used to ligate introduced DNA in recipient cells
2. It serves as a selectable marker
3. It is isolated from a virus
4. It remains active at high temperature

Q. Which of the following enzymes are used in PCR?

1. Taq polymerase
2. Ribozyme
3. Primer
4. Helicase