Biotechnology: Principles and Processes

Biology · Class 12

Simulation · Biology · Class 12

Heat shock: getting DNA into E. coli

"Heat shock: getting DNA into E. coli" is a free, interactive Class 12 Biology simulation for NEET, built on the NCERT section "Plant and animal vectors, and competent hosts" in Biotechnology: Principles and Processes. Making E. coli competent: divalent cations, ice, a brief 42 °C shock, ice again; wrong steps give few or no transformants. NEET has asked about this idea 1 time in 10 years of papers.

From the lesson Plant and animal vectors, and competent hosts in Biotechnology: Principles and Processes. Change the values and watch what happens.

Heat shock: getting DNA into E. coliBiology · Class 12

What it shows

NCERT §9.2.2 (iv), §9.2.3

Making E. coli competent: divalent cations, ice, a brief 42 °C shock, ice again; wrong steps give few or no transformants.

Controls

4 to try

  • ToggleCaCl₂ added or not
  • Sliderheat-shock temperature 30–95 °C
  • Slidershock duration 0–120 s
  • Readouttransformants on ampicillin plate (schematic)

Try this

Get the plate full of transformants by running the correct sequence.

Common mistake

Giving the heat-shock temperature as 72 °C or 94 °C.

In NEET

10 years of papers

Asked 1 time in 10 years of NEET.

See the past questions: Cloning Vectors, Biotechnology: Principles and Processes (chapter)

The idea behind it

NCERT §9.2.2 (iv), §9.2.3

  • Methods of moving genes into plants and animals were learnt from bacteria and viruses. These pathogens deliver genes into eukaryotic cells and make the cells serve them.
  • Agrobacterium tumefaciens, a pathogen of several dicots, delivers a piece of DNA called T-DNA. The T-DNA turns normal plant cells into a tumour that makes chemicals the pathogen needs. Retroviruses turn normal animal cells cancerous.
  • The tumour-inducing (Ti) plasmid of Agrobacterium has been modified into a cloning vector. It no longer causes disease but still delivers chosen genes into many plants. Disarmed retroviruses deliver desirable genes into animal cells.
  • DNA is hydrophilic and cannot pass through cell membranes, so bacteria must first be made competent to take it up.
  • Cells are treated with a set concentration of a divalent cation, calcium for example, which helps DNA get in through pores in the cell wall more efficiently.
  • The cells are incubated with recombinant DNA on ice, placed briefly at 42°C (heat shock), and returned to ice. This lets them take up the DNA.
  • Micro-injection: recombinant DNA is injected directly into the nucleus of an animal cell.
  • Biolistics (the gene gun), used for plants: tiny particles of gold or tungsten, coated with DNA, are fired into the cells at high velocity.
  • Disarmed pathogen vectors transfer recombinant DNA into the cells they are allowed to infect.

Questions

4 answers

What does the "Heat shock: getting DNA into E. coli" simulation show?
Making E. coli competent: divalent cations, ice, a brief 42 °C shock, ice again; wrong steps give few or no transformants.
What mistake does the "Heat shock: getting DNA into E. coli" simulation fix?
A common mistake it clears up: giving the heat-shock temperature as 72 °C or 94 °C.
Has NEET asked about this idea?
Yes. NEET has asked about this idea 1 time 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 "Plant and animal vectors, and competent hosts" in Biotechnology: Principles and Processes (Class 12 Biology).

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