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Slide 6 
GENETIC ENGINEERING WITH BACTERIAL PLASMIDS 
CHROMOSOME REASSEMBLY 
I brought along a little set of beads to try to illustrate to you who 
would prefer to see it in this way. This is a set of beads, and if your 
imagination can be allowed to project it to be a double-stranded DNA mole- 
cule, the segments here are meant to indicate different genes located 
linearly along the DNA molecule. 
What was found was essentially that there is an enzyme available that 
can cut the DNA at specific locations to produce bits. So we can produce a 
large number of different kinds of segments, each of them derived from a 
specific region of the cellular chromosome. 
Now, these bits can be joined together in any random fashion to pro- 
duce new arrangements by just joining the ends. I don't know what the 
order was that I had before, but it is clearly different now from what I 
showed you a moment ago. But that isn't the useful technique. The use- 
ful technique is to be able to obtain these bits in highly purified form, 
and for that there is our friend, the plasmid. 
This circular structure is meant to indicate the nature of a circular 
DNA which can serve as the vector for carrying segments of DNA and for 
amplifying them through bacteria. What I said needs to be done is to break 
the plasmid in such a way as to convert it into a linear structure, and 
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