Biotechnology: Principles and Processes

Biology · Class 12

Simulation · Biology · Class 12

One PCR cycle: set the three temperatures

"One PCR cycle: set the three temperatures" is a free, interactive Class 12 Biology simulation for NEET, built on the NCERT section "PCR" in Biotechnology: Principles and Processes. One PCR cycle as a temperature trace: strands separate when hot, primers anneal on cooling, polymerase extends at its working temperature. NEET has asked about this idea 4 times in 10 years of papers.

From the lesson PCR in Biotechnology: Principles and Processes. Change the values and watch what happens.

One PCR cycle: set the three temperaturesBiology · Class 12

What it shows

NCERT §9.3.3

One PCR cycle as a temperature trace: strands separate when hot, primers anneal on cooling, polymerase extends at its working temperature.

Controls

3 to try

  • Dragtemperature setpoints for three steps on a cycle chart (40–100 °C)
  • Togglepolymerase — Taq / heat-sensitive
  • Readoutstrands separated, primers bound, strands extended

Try this

Program a cycle in the right order (denature → anneal → extend) that gives two full copies.

Common mistake

Mixing up the order of PCR steps; assuming any polymerase survives cycling.

In NEET

10 years of papers

Asked 4 times in 10 years of NEET.

See the past questions: Polymerase Chain Reaction, Biotechnology: Principles and Processes (chapter)

The idea behind it

NCERT §9.3.3

  • PCR, the polymerase chain reaction, synthesises many copies of a gene or DNA of interest in vitro.
  • It uses two sets of primers and the enzyme DNA polymerase. Primers are short, chemically synthesised oligonucleotides complementary to regions of the DNA.
  • Each cycle has three steps: denaturation of the double-stranded DNA, annealing of the primers, and extension of the primers.
  • The polymerase extends the primers, using the nucleotides supplied and the genomic DNA as the template.
  • Repeated many times, the process amplifies the DNA segment about a billion times, giving roughly 1 billion copies.
  • Repeated cycles are possible because the DNA polymerase is thermostable. It is isolated from the bacterium Thermus aquaticus and stays active through the high temperature used to denature the DNA.
  • The amplified fragment can then be ligated into a vector for further cloning.

Questions

4 answers

What does the "One PCR cycle: set the three temperatures" simulation show?
One PCR cycle as a temperature trace: strands separate when hot, primers anneal on cooling, polymerase extends at its working temperature.
What mistake does the "One PCR cycle: set the three temperatures" simulation fix?
A common mistake it clears up: mixing up the order of PCR steps; assuming any polymerase survives cycling.
Has NEET asked about this idea?
Yes. NEET has asked about this idea 4 times in 10 years of papers.
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "PCR" in Biotechnology: Principles and Processes (Class 12 Biology).

Embed this simulation

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