PCR technique question

[SaintJude]

When April test takers said that they saw lots of molecular bio, I assume that PCR introduced in a passage is fair game. The following is an excerpt of a procedure introduced in a Kaplan BS Section Test

SGLT1 (a protein) RNA was isolated from two patients and transcribed into cDNA by reverse transcriptase. An allotment of the segments of cDNA coding for the gene was then amplified using PCR and sequenced while the remaining portion was cut with the restriction enzyme and analyzed using a southern blot.

Why would the scientist sequence the code? What does sequencing actually do ?

And why would the scientist sequence DNA and cut with a restriction enzyme?

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[bajoneswadup]

molecular markers bro, super importanto. see wat genes up in dat molecule

 

[SaintJude]

When people answer the way you do, I wonder are you interested in offering an explanation..or just racking up posts? In short, what are you saying?

 

[bajoneswadup]

When people answer the way you do, I wonder are you interested in offering an explanation..or just racking up posts? In short, what are you saying?

PCR is used for identifying genes. You can look up the process, it's only about 5 steps then it repeats, but basically you can take a small amount of DNA and make millions of copies of it. Smart ppl use PCR for tons of things now days, including things like finding genes and creating cladograms. Here's the steps I looked up my old biochem test. First you put the DNA in a test tube and stick it
in the PCR. It will heat the sample up till it denatures the DNA. Then you add the nucleotides they will hybridize to the DNA. Then you add heat sensitive DNa polymerase which will bind them together, and then you cool& repeat. It's really simple way to go from 1 dna molecule to millions in a few hours.

 

[lesset01]

The reason why someone would sequence DNA and cut with an RE is because in addition to knowing the nucleotide sequence of DNA, you also want to know where the sequences are different between people. Since comparing sequences 1 nucleotide at a time is tedious (not so much now with computer programs but still takes a while), cutting with an RE tells you right away where the sequences are different because they will have different size bands. This can help determine the presence or absence of something like a gene or DNA insertion/deletion.

Molecular markers are like little "flags" in the DNA that you can always find easily and use to locate things like the locus of a gene of interest. Think of them like "mile markers" on one long stretch of highway that looks pretty much the same down its length, how would you locate a car that was broken down? The RE sites help you locate these markers.