Biotechnology
Genetic Engineering
Bacterial Genome
Bacteria are special for many reasons, one of which being that they can have DNA
outside of their normal genome. This DNA is called a plasmid. Plasmids are circular,
and much smaller than the bacterium’s standard chromosome. They can
incorporate themselves into the standard chromosome, or exist separately.
Whether thay are separate or not, they always work.
Below is a man-made plasmid that can be inserted into bacteria. Natural bacterial
plasmids are very similar (being circular, and having only 2 or 3 genes), but they
don’t have the special “polylinker” site. This polylinker allows scientists to insert
whatever gene they like, such as the gene that makes human insulin.
Genetic engineering is the process by which an organism’s genetic code is manually
changed in some way. The diagram below shows one of the simplest versions of
genetic engineering. This is the process by which a human insulin gene is inserted
into a bacterial clone. Plasmids will replicate with the bacterial cell.
One last thing: not all the bacteria are able to pick up the DNA. So, this means we
have to test to see which ones picked it up using a marker, or probe. These probes
can be anything easily seen, such as radioactivity, or green fluorescence.
Key Terms:
Vector
Plasmid
Restriction endonuclease
Ligase
Recombinant DNA
Clone
Probe
Questions
1. What is a probe used for?
2. What’s the function of a polylinker?
3. If I wanted to insert 3 genes into a polylinker, how many restriction enzymes
should I use?
4. What’s the function of the ampicillin gene?
5. When would I be able to see a probe work?
6. What is the latest kind of probe used? (hint: The developer won a Nobel Prize)
7. What enzyme must accompany the gene you try to insert into an organism?
8. I stated above that a plasmid is always working. What do I mean by “working?”
(Hint: what is the function of DNA, and what does it code for?)
* News update: The glow-in-the-dark pigs had babies! Two of the five in the litter
glow-in-the-dark. This means that scientists were able to insert a gene into a onecell embryo (the smallest baby you can have), the pig grew and had babies, and the
gene was successfully passed on to the offspring. The research company stated the
next step was to attempt to grow organs that can be transplanted from a pig into a
human.
This research is being done in China, where all ethical ideas are dictated by the
communist ruler. Would you invest in a U.S. company to do this?