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Discussion Starter · #1 ·
A researcher has designed a study in which she will compare the variability of alleles for two hundred genes on four chromosomes between two populations: two thousand children with low-functioning autism and two thousand children with no developmental or other disorder. Which tool will be the most useful for identifying allele variability?
  • Allele-specific oligonucleotide probes
  • DNA hybridization chips
  • Small interfering RNA
  • Restriction fragment length polymorphisms
  • Variable number tandem repeats
 

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B) DNA hybridization chips

This method used by scientist to compare the variability of alleles for certain genes by using four synthesized DNA target.

This is a tough one, you can answer this type of qn only if you know the gene analyzing Techniques, otherwise you screwed. :rolleyes:
 

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Discussion Starter · #6 ·
Answer

The correct answer is D. Restriction fragment length polymorphisms. I know this was kind of a hard one, since the subject is somewhat obscure. I think it's probably pretty low-yield...

RFLP's are useful when a researcher is looking for genetic variabilty but isn't sure what the variablity will look like. It's rarely used for diagnosis of specific diseases these days, since there are more precise methods now that we have sequenced the genome and located the specific mutation for so many diseases. An example that everyone should be familiar with is a cartoon of a gel run for a paternity that has been on everyone's genetic tests.



Allele-specific oligonucleotide probes (A) might be appropriate to identify a particular mutation (or two hundred, in this case), or to count chromosomes. Everyone should be familiar with this idea from the image of FISH for trisomy that you have likely seen in your textbook:



A DNA hybridization array chip (B) could be used for that too, or to identify a set of single nucleotide polymorphisms, although it's most commonly used to measure gene expression in certain cells or tissues. This would be the next best answer, but the researcher would have to have a good idea about the specific mutations.



siRNAs (C) would be used to modulate gene expression at the transcriptional/post-transcriptional level.



VNTRs (E) are used for DNA fingerprinting. They might be used in a study like they one mentioned, but again, only if the researcher had a pretty good idea where to look, or in an instance where the repeats themselves are the mutation, as in Fragile X; this would not likely be the case in two hundred genes! A more likely use of this tool would be a study tracing the lineage of a particular mutated allele.



I wouldn't get too hung up on these, as I doubt it's a very high-yield subject. A senior of mine told me "whenever you come to a question with some testing technique, choose PCR analysis, that should do you for the boards." :eek:
 
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