IMAT 2016 Q28 [Production of Transgenic Plants]

Below are some steps involved in the production of transgenic plants.

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Which one of the following options gives a correct order for these steps?

A. W → Z → X → V → Y
B. W → Z → X → Y → V
C. Z → W → V → Y → X
D. W → V → Z → X → Y
E. Z → W → V → X → Y

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The correct answer is E.

What is a transgenic organism ?

A transgenic organism is a genetically modified organism (GMO). Such a thing can be accomplished by transgenesis, which is the insertion of one or several new genes inside the genome.

How does transgenesis work?

There are multiple steps to transgenesis. The first one is to identify the gene of interest : it is either a gene that will give a new advantageous caracter to the organism or a gene that we want to study in particular.

Then, we have to incorporate the gene of interest inside a genetic construction. Those will then be multiplied and then transferred. That is possible thanks to genetic transformation. It is a type of horizontal transfer : from one organism to another that ISN’T its offspring. .

Then what is the right order ?

1) Use of restriction enzymes to produce sticky ends in the plasmid

To be able to link the DNA backbone to the DNA insert, there needs to be “sticky ends” (picture 2 blocks of LEGOs you want to put together).

They are obtained by using restriction enzymes that will cut the ends unevenly.

Compatible sticky ends stick together and result in the formation of a recombinant DNA.

2) Isolation of the required gene using restriction enzymes

To separate the gene of interest, restriction enzymes are used (like we said, they cut the DNA strands).

3) Mixing the required gene and the plasmid with ligases

Ligases are enzymes that can stick together 2 bits of DNA strands. Therefore, they are used to stick the gene of interest to the plasmid, which will be inserted into the plant cell.

4) Identification of the recombinant plasmid

The recombinant plasmid is the one that has successfully integrated the gene of interest into its sequence. It can be identified through the usage of DNA probes.

DNA probes are sequences of nucleotides that can help identify complementary sequences because they have a fluorescent dye.

5) Injection of plasmid into host plant cell

Once the recombinant plasmid has been successfully identified, it has to be injected into the host plant cell. That is where the biological transformation happens.

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