ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Biology => Topic started by: morrjs on August 13, 2008, 08:58:23 pm
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I have a set of questions from AOS 1 which are revision. I am having trouble with one. I don’t know what to write.
1) Discuss the importance of restriction enzymes in DNA manipulation experiments.
* They are the first step….without them DNA manipulation could not occur????
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they allow you to isolate genes and splice them onto other DNA molecules.
electrophoresis would not work without them...
basically what you said...you cant manipulate DNA without restriction enzymes.
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Ahhh good...there was no hidden meaning...thanks heaps mate :)
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Restriction enzymes are used to cut DNA into fragments that may yield "sticky" or "blunt" ends. They are important in that they cleave DNA at a specific sequence of bases (known as the recognition sequence/site) ; and as the same restriction enzyme always splices at the same sequence of bases - two pieces which have been cut by the same restriction enzyme will be complementary to each other and will therefore join (forming H bonds with one another). (DNA ligase is used to join the back-bone together - which requires covalent bonding).
This means that fragments from one source (for example... humans) can be made to join to fragments from another (eg; ..bacteria).
In short ... restriction enzymes permit the splicing of different DNA molecules from a range of sources to form recombinant DNA.
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In my text book it defines gene probes like this:
A purified fragment of single stranded DNA labelled with a radioactive isotope or fluorescent dye that will hybridise to a complementary region among fragments of DNA in a sample.
I don't understand what it means by 'hybridise', I always assumed that it simply bound to the complementary sequence of DNA to mark it.
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I think thats just a fancy word for 'join on to'...the most common word they used if I remember correctly was 'anneal'?
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Mmm I hope so, they use the word 'anneal' when they talk about primers (which I thought bound to the DNA strands in the same way but only for a different purpose) and this is why I started to think that 'hybridised' meant something different happened.
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Hybridise pretty much = anneal
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Lol mk, thanks man...stupid hienemann textbook making it so confusing =_=