Unit 2-5 Notes

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Genetic Testing

• Unit 2-5 Notes
• Mr. Hefti Pulaski Biology

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1. Summary of Steps

• Gene testing
• Collect cells (blood sample)
• Make copies of the DNA (PCR)
• Separate the DNA (gel electrophoresis)

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2. Gel Electrophoresis

• DNA moves through gel based on size
• Smaller fragments
• travel faster than
• larger fragments!!!

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3. Huntington Disease Gene

• HD gene contains extra CAG nucleotide repeats,
  therefore are larger in size than normal gene

CAGCAGCAGCAGCAG
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4. Results

• Compare patients DNA test results to control
  samples

Lane 1 no sample Lane 2 Positive
control Lane 3 Negative control Lane 4
Patient A Lane 5 Patient B Lane 6 Patient C
Larger DNA fragments end up here
Smaller DNA fragments end up here
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5. Example HD Pedigree
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