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DNA Identification

Ch 9-1 & 9-2. DNA Identification. The repeating sequences in noncoding DNA vary between individuals and thus can be used to identify an individual. Steps in DNA Identification. Copying DNA

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DNA Identification

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  1. Ch 9-1 & 9-2 DNA Identification • The repeating sequences in noncoding DNA vary between individuals and thus can be used to identify an individual.

  2. Steps in DNA Identification • Copying DNA • To identify a DNA sample, scientists isolate the DNA and copy it using thePolymerase Chain Reaction (PCR) • Millions of copies are made in just a few hours

  3. Polymerase Chain Reaction

  4. Steps in DNA Identification • Cutting DNA • The DNA is then cut into fragments using restriction enzymes • Restriction enzymes recognize and cut specific nucleotide sequences called a restriction site.

  5. Restriction Enzymes Cut DNA

  6. Steps in DNA Identification • Sorting DNA by Size • The fragments are separated by size using gel electrophoresis • A positive electrode is attached to one side of the gel (a thin slab of hard gelatin) • A negative electrode is attached to the other side • An electric current is sent through the gel and the DNA (which is slightly negative) moves towards the positive side

  7. Steps in DNA Identification • Sorting DNA by Size • There are pores in the gel for the DNA to move through • Large pieces of DNA stop sooner (closer to the negative end) • Small pieces of DNA move farther (closer to the positive end) • The resulting pattern of bands is called a DNA fingerprint • a Restriction map shows the lengths of the bands produced in the gel

  8. Gel Electrophoresis

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