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Genetic Technology: Question 6

Syllabus 19.1

Multiple choice A2 1 mark

Which statement correctly distinguishes gene editing from the gene transfer techniques of genetic engineering, such as inserting a gene into a bacterial plasmid?

Choose an answer to check it, then compare with the worked solution below.
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Worked solution

Working through the options

Genetic technology includes two related but distinct approaches to changing an organism’s genetic material, and it is easy to blur the line between them.

Gene transfer (the classic genetic engineering approach seen in producing recombinant proteins) inserts a gene, often taken from a different organism, into a vector such as a plasmid, which then carries the gene into a host cell so it can be expressed as a completely new addition to that cell’s genome.

Gene editing works differently: a short guide RNA, whose base sequence is complementary to a specific target sequence in the organism’s own genome, binds to that target sequence and directs an enzyme (commonly Cas9) to cut the DNA at precisely that point. Because the guide RNA can be designed to match almost any sequence, the cut can be made at a chosen location within a gene the organism already possesses. The cell’s own repair processes then mend the cut, which can disable the gene, or, if a template is supplied, correct or alter its sequence. No gene from another species has to be added for this to work.

Checking each option:

  • A, reverses the two definitions; incorrect.
  • B, correctly describes gene editing as a targeted cut, directed by a guide RNA, within the organism’s own genome, and gene transfer as insertion of an entirely new gene via a vector. Correct.
  • C. Gene editing does not require inserting a gene from another species at all; incorrect.
  • D, both techniques ultimately act on DNA within the genome, not on isolated RNA; incorrect.

Final answers

  • B, gene editing uses a guide RNA to direct an enzyme such as Cas9 to cut and alter a specific sequence within an organism’s own genome; gene transfer techniques insert an entirely new gene using a vector such as a plasmid.