K325 / 2027

Lesson 4 of 6 / Molecular genetics

Transferring a gene between organisms

What changes when a cell receives new genetic information?

I can explain gene transfer and the formation of a transgenic organism.

  • I can explain gene transfer between organisms to form transgenic organisms.Syllabus

    Syllabus K325, Topic 12(f). Explain gene transfer between organisms to form transgenic organisms.

About 4 min

Make a guess. You are not marked.

A human gene for a protein is put into a bacterium. What does the bacterium gain?

  1. The ability to make that one protein.
  2. Human features, because it has human DNA.
  3. Nothing, because human genes cannot work in bacteria.
Show the answer

The ability to make that one protein.

The bacterium stays a bacterium. If the gene works, its cells can now make the protein the gene codes for.

The key idea

A gene can be transferred into cells of another organism. If the introduced gene is maintained and used, it can give the recipient a new ability to make a particular product.

A transgenic organism contains introduced genetic material originating from another organism. A vector is a carrier used to transfer DNA into a recipient cell.

Explore the idea

New information, same recipient organism

Recipient before transferThe bacterial chromosome remains present. The selected introduced gene is not yet in this recipient.Bacterial chromosomePlasmid

The recipient already has its own chromosome and cell structures. Gene transfer adds selected information; it does not replace the whole cell with the donor.

Original schematic. Purple is existing DNA, orange is introduced information or its product. A gene entering a cell does not by itself guarantee stable maintenance or successful expression.

Explanation

Genetic engineering can transfer a selected gene from cells of one organism into cells of another. The introduced DNA provides information for a particular product. An organism carrying such introduced material is described as transgenic in this context.

The transferred gene must enter the recipient cells and be maintained in a suitable form. For the intended trait to appear, the cells must also be able to use the gene's information and make a functional product. Merely placing a piece of DNA beside a cell is not enough.

A carrier, or vector, can help deliver the DNA. Plasmids are small circular DNA molecules that can be used as vectors in bacteria. The recipient bacterium retains its existing cell structures and most of its genetic information while gaining the introduced sequence.

Gene transfer differs from feeding an organism a protein. A protein supplies the finished molecule temporarily; a working introduced gene can enable recipient cells to make the product themselves. The next lesson applies this distinction to human insulin production.

Step by step
  1. 1

    Choose the desired information

    Identify the gene associated with the product or feature sought.

  2. 2

    Transfer it in a usable form

    A suitable carrier and recipient system are required for the introduced DNA to be maintained and used.

  3. 3

    Check the intended result

    The recipient should make the expected product; gene entry alone does not prove correct expression or function.

Worked example

A bacterium receives an insulin-coding sequence

Explain why the bacterium can potentially produce human insulin without becoming a human cell.

One way to explain it

The introduced sequence carries information for the insulin product. If the bacterial production system can use it appropriately, it gains that protein-producing ability. It still retains bacterial structures and its wider bacterial genetic information, so it remains a bacterium.

Why this answer works
  • Identify what the transferred sequence specifies.
  • Qualify the need for a working production system.
  • Distinguish one new product from whole-organism identity.

Watch out for this

A student says: "Transferring one gene transfers every characteristic of the donor." What is wrong with this?

Show the answer

A selected sequence provides particular information. The recipient retains its other genes and structures; it does not become the donor organism.

Check your understanding

What is transferred to create the intended new protein-producing ability in a transgenic recipient?

  1. A suitable DNA sequence containing the gene information.
  2. The donor's entire body and every cell structure.
  3. A dose of the finished protein, which the recipient's cells then keep making.
Show the answer

A suitable DNA sequence containing the gene information.

The recipient must also maintain and use that information appropriately to make the intended product.

Quick recall

Card 1 of 3. Answer in your head, then check.

What changes when a cell receives new genetic information?

You can return to this lesson any time.