LEQ: How Does DNA profiling work?

1
LEQ How Does DNA profiling work?

• 12.8 to 12.12

2
Nucleic Acid Probes

• Short single strands of DNA w/ specific
  nucleotide sequences are created using
  radioactive isotope or dye
• These probes are used to find a specific gene or
  nucleotide sequence the probe hydrogen bonds to
  gene of interest

3
DNA Microarray
4
DNA Microarray test for gene activity

• mRNA that produces protein of interest is
  isolated, reverse transcriptase fluorescent
  nucleotides are added
• cDNA is made from RNA
• cDNA is applied to well that contain DNA from a
  cell cDNA will bind to DNA that is complementary
  in the wells
• Rinse unbound cDNA fluorescent spots show DNA
  that is being expressed by the cell no glow
  unexpressed DNA
• Enables a researcher to determine what genes are
  turned on or off in a cell

5
Gel Electrophoresis

• Negatively charged DNA is placed into the wells
  at the negative end of the gel apply current
  negative DNA is pulled to the positive end
  smaller pieces travel farther faster DNA
  fragments are separated based on the size of the
  fragment ( of base pairs).

6
Restriction Fragment Length Polymorphisms (rflps)

• (rif'-lips) The differences in homologous DNA
  sequences that are reflected in different lengths
  of restriction fragments produced when the DNA is
  cut up with restriction enzymes
• Here you are looking at homologous chromosome
  segments one from a crime scene and the other
  from the suspect when you cut both with the same
  restriction enzyme, they produce different
  banding patterns This tells you the crime scene
  DNA did not come from the suspect

7
RFLIPs used to ID Harmful alleles

• Compare individual that has a disease/harmful
  allele to others. Digest DNA from all
  individuals using same restriction enzyme. Run
  gel electrophoresis. Blot DNA (pick up DNA using
  special filter paper). Apply radioactive probe
  designed to detect (bind to) harmful allele /
  gene of interest. Unattached probes are rinsed
  off. Photographic film used to form a image that
  compares individuals. In this picture I had
  the harmful allele. If any individual matches
  the banding pattern of I, then they also have the
  harmful allele. Individual II has the harmful
  allele but III doesnt.

8
DNA Fingerprinting

• A procedure that analyzes an individuals unique
  collection of DNA restriction fragments, detected
  by electrophoresis and nucleic acid probes. DNA
  fingerprinting can be used to determine whether
  two samples of genetic material are from the same
  individual.
• Used to convict criminals, determine paternity,
  exonerate innocent individuals, etc