C
CraftExam
medium difficulty6 min

Tools of Recombinant DNA Technology

The tools of recombinant DNA technology are biological agents and systems used to cut DNA, join DNA, carry foreign DNA and introduce it into a host cell.

In one line: Cut, carry, join, host: enzyme cut, vector carry, ligase join, cell grows.

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Understand it

  • Recombinant DNA technology depends on tools with specific functions.
  • Restriction endonucleases cut DNA at particular recognition sequences, producing fragments that can be joined with vector DNA.
  • DNA ligase seals compatible DNA ends, forming a recombinant molecule.
  • Polymerases help synthesize or amplify DNA, especially during PCR.
  • Cloning vectors such as plasmids carry the desired DNA into host cells, while competent host cells accept the vector and multiply it.
  • EcoRI is a standard example of a restriction enzyme; its name reflects the organism source and strain information.
  • Exam questions often test tool-function matching rather than broad definitions.

Example

EcoRI can cut DNA at a specific palindromic recognition site, and DNA ligase can join a desired DNA fragment into a plasmid vector such as pBR322.

Rule to remember

Tool-function rule: restriction enzymes cut at specific sites, ligase joins DNA ends, polymerase synthesizes DNA, vectors carry DNA, and host cells maintain or express the recombinant DNA.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

If asked to name two enzymes used in rDNA technology, write restriction endonuclease for cutting DNA at specific sequences and DNA ligase for joining the desired fragment to vector DNA.

Method you can reuse

Choose a restriction enzyme that cuts the desired gene and vector at compatible sites; isolate the DNA fragment; use ligase to join fragment and vector; introduce the recombinant vector into a competent host; select transformed cells.

Visual tip

For pBR322 or vector diagrams, label ori, antibiotic resistance genes, restriction sites such as EcoRI or BamHI, and cloning site; notice that each label has a selection or replication function.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

What is the role of DNA ligase in recombinant DNA technology?

Think first, then show answer
DNA ligase joins the desired DNA fragment with vector DNA by sealing the sugar-phosphate backbone. It helps form a stable recombinant DNA molecule that can be introduced into a host cell.

Common wrong answer

EcoRI is a vector used to carry foreign DNA.

Don't mix this up

A common error is saying restriction enzymes join DNA; they cut DNA, while ligase joins DNA fragments.

Exam tip

For tool questions, write the tool name with its exact function: restriction enzyme cuts, ligase joins, vector carries, host cell multiplies.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Asked through tool-function matching, EcoRI naming, pBR322 diagram labels, and short answers on why competent cells are prepared.

Answer plan

Define rDNA tools, list restriction endonuclease, polymerase, ligase, vector and host cell, state one accurate function of each, and add a labelled vector example when the question asks for a diagram.
  1. 1

    Enough for 1 mark

    The tools of recombinant DNA technology are biological agents and systems used to cut DNA, join DNA, carry foreign DNA and introduce it into a host cell.

  2. 2

    Add for 2 marks

    Example: EcoRI can cut DNA at a specific palindromic recognition site, and DNA ligase can join a desired DNA fragment into a plasmid vector such as pBR322.

  3. 3

    Add for 3 marks

    Recombinant DNA technology depends on tools with specific functions.

Practice

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