DNA manipulation questions...

[morrjs]

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?

[bucket]

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.

[morrjs]

Ahhh good...there was no hidden meaning...thanks heaps mate

[Toothpaste]

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.

[bucket]

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.

[shinny]

I think thats just a fancy word for 'join on to'...the most common word they used if I remember correctly was 'anneal'?

[bucket]

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.

[NE2000]

Hybridise pretty much = anneal

[bucket]

Lol mk, thanks man...stupid hienemann textbook making it so confusing =_=