Cells and microorganisms are already so small, that I find it hard to imagine how someone can be looking through a microscope with tiny scissors or something cutting DNA or RNA from the nucleus of a cell. Also they are able to cut specific genes from those strands of DNA/RNA. How do they even read the genes. Also then how do they extract it out the cell and then insert it in another, or set it aside etc.
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How we do it has changed a lot over the past 40 years. Exactly what we do depends on what we’re trying to accomplish.
Most of the time, we just want a bunch of copies of a chunk of DNA. In that case, we use something called PCR. If you imagine DNA as a long ribbon, we can copy any part by knowing a tiny bit of sequence at either end of the chunk we want to copy. In PCR, you mix the fragments at the ends with the DNA, and the enzyme from a cell that duplicates DNA and they you just warm and cool it and the enzyme pumps out copies of the DNA segment you wanted.
We can also use enzymes that will cut DNA at specific patterns (restriction enzymes), and even “program” enzymes to cut at very specific places (CRISPR+Cas9) using short DNA pieces to tell it where to cut.
Much of this relies on our ability to make short DNA sequences to order. You can get a shoebox-sized thing that plugs into a computer that can “print” short custom DNA sequences.
It also relies on DNA sequencing (now very cheap, and there’s lots of databases of DNA sequence).
For RNA, we use an enzyme to make DNA copies of it (reverse transcriptase) and just do the DNA stuff.
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