In the tobacco experiment the inserted DNA was arranged to make both sense and antisense RNA of a…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In the tobacco experiment the inserted DNA was arranged to make both sense and antisense RNA of a nematode gene.
- What forms when the two RNA strands meet in the plant cell?
- Suppose a plant made only the sense strand. Would RNA interference start? Explain.
- Name the vector that was used to put the DNA into the tobacco cells.
- What happens to the nematode, and why?
Need a reminder? The key ideaShow
RNA interference (RNAi) is a defence of eukaryotic cells. A double stranded RNA that is complementary to a messenger RNA silences it, so the mRNA is not translated. In tobacco, a nematode gene was introduced with an Agrobacterium vector so that the plant made both sense and antisense RNA. These formed double stranded RNA, and the nematode could not survive on the plant. In double stranded RNA, A pairs with U by 2 hydrogen bonds and G pairs with C by 3.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. (a) A double stranded RNA, because the two strands are complementary.
Step 2. (b) No. A single strand with the same sequence as the mRNA has nothing complementary to pair with, and there is no double strand to start the silencing.
Step 3. (c) Agrobacterium.
Step 4. (d) The dsRNA silences the specific mRNA of the nematode, so its protein is not made. The parasite cannot survive in the transgenic plant.
Answer: (a) dsRNA; (b) no, there is no double strand; (c) Agrobacterium; (d) the specific mRNA is silenced and the parasite cannot survive.
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