How do we use Polymerase Chain Reaction in determining its particular DNA code?

Answer 1

Your question is rather general.

You should go to textbooks like "Molecular Biology of the Cell" by Alberts et al, to read the about the principle of the technique.

One way to do it, is to use the unknown sequence as a template, a primer that will anneal at the beginning of the sequence, a mixture of dTTP,dCTP,dGTP, dATP and an analogue of dATP that stops the reaction.
This way you will create a lot of molecules of different length, always stopping at an A (you use the mixture of dATP and its analague because if you used only the analogue the reaction would stop at the very first A the polymerase adds. Using the mix gives a certain probability that the analague is incorporated and thus you can get molecules that will have inside them normal A but always stop at A).

You repeat this experiment using analogues for the other dNTPs.
You analyze the samples by gel electrophoresis and you can find the sequence of the DNA by reading the bands from bottom to top. E.g let's assume you have the unknown sequence

TTACGATCA... (your template being the reverse complement)
Then if you used only the dATP analogue the reaction would give only one fragment (TTA). Using the mixture of all dNTPs+the dATP analogue you will get
Lots of TTA (3 bases size)
fewer TTACGA (6 bases size)
fewer TTACGATCA (9) and so on
Then you repeat the experiment with all dNTPs + a dTTP analogue.

You get T (1)
TT (2)
TTACGAT (7)

Then you repeat with all dNTPs+ a dCTP analogue and get
TTAC (4)
TTACGATC (8)
and finally with a dNTPs+ a dGTP analogue and get
TTACG (5)

Then you run them on the gel and the bigger fragments run slower so they are going to be at the top of the gel. You use radioactive dNTPs so that you can visualize the bands. The first lane has the reaction mixture with the dATP analogue (A), the second of the T, 3rd C, 4th G. The asterisk shows where you would see a band

Size.. .. .. A .. .. T .. .. C .. .. G
9.. .. .. .. ..*
8.. .. .. .. .. .. .. .. .. .. .. *
7.. .. .. .. .. .. .. .. *
6.. .. .. .. ..*
5.. .. .. .. .. .. .. .. .. .. .. .. .. .. ..*
4.. .. .. .. .. .. .. .. .. .. .. *
3.. .. .. .. .. *
2.. .. .. .. .. .. .. .. *
1.. .. .. .. .. .. .. .. *

So we start reading from bottom to top.
First band we see is in the lane of T, thus our first base is T, second again is T and so on till we get the full sequence.

Answer 2

The polymerase reaction breaks the DNA chain down into amino acids

Which can then be identified using mass spectral analysis

Answer 3

The technique is so fundamentaly simple. Starting with a long double-stranded DNA molecule containing a short sequence he wished to study and copy, he heated the long molecule to separate the strands. next he added short pieces of DNA that can be designed to "bracket" the desired DNA sequence, attaching to either end of the other separated strand. then we add the DNA polymerase, the enzyme needed to synthesize new chains of DNA bases,a nd waited for it to generate a copy of each bracketed DNA segment......may this help you a bit...need to go...