6. How do you know if the halibut you purchased at the supermarket is really halibut? To identify the source of a biological sample, scientists PCR amplify and then sequence a region of DNA known to...

6. How do you know if the halibut you purchased at the
supermarket is really halibut? To identify the source
of a biological sample, scientists PCR amplify and
then sequence a region of DNA known to vary between species. For animals, this DNA region is a
648–base pair portion of the mitochondrial cytochrome oxidase I gene. The sequence of this mtDNA
region acts as a so-called DNA barcode because a
database exists that contains the sequences of this
mtDNA region that are unique for hundreds of
thousands of animal species.
a. Why do you think that a region of mitochondrial
DNA is used for barcoding animals, as opposed to
a region of nuclear genomic DNA?
b. A single pair of PCR primers can be used to
barcode any species of fish. Explain how this is
possible.
c. List criteria that scientists would have considered
when determining which mitochondrial DNA
sequence to use for barcoding animals.