Question: How do you manage to clone DNA?

David Walker-Sünderhauf answered on 9 Mar 2019: last edited 9 Mar 2019 8:41 am

The most basic molceular cloning has 3 steps:
“Restriction” — this step involves cutting DNA. One part of DNA I’m cutting will usually be a ‘plasmid’. This is an extra bit of circular DNA bacteria can take up. The other bit will be a gene of interest, for example as in the picture an insulin gene.
For this, I can use “restriction enzymes”. These are enzymes originally involved in bacteria for defense, which always cut DNA at the same sequence, this makes it easy to decide which restriction enzymes I need to use to cut out a certain gene.
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“Ligation” — this is basically “gluing” the two bits of DNA together. Using the same restriction enzymes for both bits of DNA in the first step creates the same ‘sticky ends’ on the DNA (the short overhangs in the picture), this makes it easier for the ligase enzyme to align the DNA properly and then glue it together.
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“Transformation” — this one isn’t on the picture, but once you have the finished product, it’s still useless like that – you need loads of copies of it to work with it! To do that, I induce bacteria to take up the plasmid by ‘transforming’ them. If you heat-shock or electro-shock certain strains of bacteria, they will take up plasmids like this. Then, when the bacterium amplifies, so does the plasmid! I can extract it afterwards and have plenty of cloned DNA to work with.

Let me know if you want to know more about any of the steps or other cloning techniques 🙂

(Picture credit: Khan Academy)