Genetics

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bigballer27

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it seems like genetics is tested enough for me to pay a little more attention to it lol.

but my book (TPR) doesnt give any info on RFLPs, and minimal info on linkage, so can anyone give concise relevant info, or should i maybe go to borders and check out an EK book there or something? not sure what to do, or is what TPR gives all the info we should know...cuz it seems minimal and nothinig complicated

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just realized i didnt really ask a specific question lol

what are RFLPs? do we even need to know them for the genetics section?
 
RFLPs are restriction fragment length polymorphisms... so its the difference in place where restriction sequences occur allowing for restriction enzymes to cut them in homologous DNA sequences from different sources. This allows for things like DNA identification matching.

Its kinda like when you would see the gel plates of an unknown criminals blood run next to the defendants blood in a court room. If they match up its due to RFLPs because they have restriction sites in the same places and thus probably came from the same source. The resulting pattern on the gel results from the size of the DNA pieces after they have been cut with restriction enzymes and everyone pretty much has a unique set of RFLPs.

hope that kinda answered your question

-Alex
 
RFLPs are restriction fragment length polymorphisms... so its the difference in place where restriction sequences occur allowing for restriction enzymes to cut them in homologous DNA sequences from different sources. This allows for things like DNA identification matching.

Its kinda like when you would see the gel plates of an unknown criminals blood run next to the defendants blood in a court room. If they match up its due to RFLPs because they have restriction sites in the same places and thus probably came from the same source. The resulting pattern on the gel results from the size of the DNA pieces after they have been cut with restriction enzymes and everyone pretty much has a unique set of RFLPs.

hope that kinda answered your question

-Alex

yeah it did simplify it a bit, thanks
 
just realized i didnt really ask a specific question lol

what are RFLPs? do we even need to know them for the genetics section?


Restriction Fragment Length Polymorphism (RFLP)

Introduction

Restriction Fragment Length Polymorphism (RFLP) is a difference in homologous DNA sequences that can be detected by the presence of fragments of different lengths after digestion of the DNA samples in question with specific restriction endonucleases. RFLP, as a molecular marker, is specific to a single clone/restriction enzyme combination.
Most RFLP markers are co-dominant (both alleles in heterozygous sample will be detected) and highly locus-specific.
An RFLP probe is a labeled DNA sequence that hybridizes with one or more fragments of the digested DNA sample after they were separated by gel electrophoresis, thus revealing a unique blotting pattern characteristic to a specific genotype at a specific locus. Short, single- or low-copy genomic DNA or cDNA clones are typically used as RFLP probes.
The RFLP probes are frequently used in genome mapping and in variation analysis (genotyping, forensics, paternity tests, hereditary disease diagnostics, etc.).
How It Works
RFLP.gif


SNPs or INDELs can create or abolish restriction endonuclease (RE) recognition sites, thus affecting quantities and length of DNA fragments resulting from RE digestion.
Genotyping
RFLP_genotyping.gif


Developing RFLP probes


  • Total DNA is digested with a methylation-sensitive enzyme (for example, PstI), thereby enriching the library for single- or low-copy expressed sequences (PstI clones are based on the suggestion that expressed genes are not methylated).
  • The digested DNA is size-fractionated on a preparative agarose gel, and fragments ranging from 500 to 2000 bp are excised, eluted and cloned into a plasmid vector (for example, pUC18).
  • Digests of the plasmids are screened to check for inserts.
  • Southern blots of the inserts can be probed with total sheared DNA to select clones that hybridize to single- and low-copy sequences.
  • The probes are screened for RFLPs using genomic DNA of different genotypes digested with restriction endonucleases. Typically, in species with moderate to high polymorphism rates, two to four restriction endonucleases are used such as EcoRI, EcoRV, and HindIII. In species with low polymorphism rates, additional restriction endonucleases can be tested to increase the chance of finding polymorphism.
PCR-RFLP
Isolation of sufficient DNA for RFLP analysis is time consuming and labor intensive. However, PCR can be used to amplify very small amounts of DNA, usually in 2-3 hours, to the levels required for RFLP analysis. Therefore, more samples can be analyzed in a shorter time. An alternative name for the technique is Cleaved Amplified Polymorphic Sequence (CAPS) assay.



Source: http://www.ncbi.nlm.nih.gov/projects/genome/probe/doc/TechRFLP.shtml


I hope this helps clarify some of the points that Alex made.
 

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