Two complaints about some transgenic plants presently in commercial use are that (1) the Bt toxin gene is constitutively expressed in them, leading to fears that selection pressures will cause insects to evolve resistance to the toxin, and (2) a selectable marker gene—for example, conferring kanamycin resistance—remains in the plant, leading to concerns about increased antibiotic resistance in organisms in the wild. How would you generate transgenic plants that produce Bt only in response to being fed upon by insects and without the selectable marker?

Question

Accepted Answer

Welcome back, everybody. Let's look at our next question. It says the cell is exposed to an electric field which creates temporary pores in the cell membrane allowing the DNA to enter. This method of gene transfer is referred to as a microinjection B electroporation, C gel electrophoresis or D vortex mixing. Well, we luckily here have a clue in the very name itself. This method of gene transfer is choice B electroporation and that has both the prefix electrode. There's going to be an electrical pulse and po it will create pores in the cell and it consists of a brief high voltage applied two cells. And as our problem says, that creates temporary pores in the cell membranes, it allows DNA R N A or other macro molecules to enter the cell while those temporary pores are are open. So let's just look at our other answer choices to understand why they're not correct and they're not too confusing here. Um to gel electrophoresis, we have that electricity element. But hopefully we recall that's a pretty common laboratory technique involving separating molecules on a gel. They run across the gel after it has an electric current applied across it, but it doesn't involve creating pores in a cell to transfer materials. So that's not our answer choice. Um Choice. A microinjection. Again, the name kind of tells us would be actually physically injecting material into the cell, which is obviously not what we're talking about here. And choice D vortex mixing, this is literally just using an electric motorized mixer commonly found in laboratories. You can hold little test tubes up to it and it gives brief um rapid mixing to a sample but not electroporation. So not our answer choice. So again, when you have a cell exposed to an electric field that creates temporary pores where DNA can enter. That's choice B electroporation. See you in the next video.

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Key Concepts

Inducible Gene Expression

Selectable Marker Genes

Gene Editing Techniques