University:
Felician University
Course:
BIO-405 | Genetics
Academic year:

2024
Views:

128

Pages:

10
Author:

Clint W.

RFLP / electrophoresis use in forensics • 1st case successfully using DNA evidence – 1987 rape case convicting Tommie Lee Andrews – Showed that DNA is DNA… no matter where it comes from “standard” semen sample from rapist blood sample from suspect “standard” “standard” semen sample from rapist blood sample from suspect “standard” Evidence from murder trial –Do you think suspect is guilty? blood sample 1 from crime scene blood sample 2 from crime scene blood sample 3 from crime scene “standard” blood sample from suspect OJ Simpson blood sample from victim 1 N Brown blood sample from victim 2 R Goldman “standard” 5. MAKING IT PERMANENT A) TRANSFERRING THE FRAGMENTS TO A NYLON MEMBRANE Southern Blot: tech puts a sturdy nylon membrane on top of gel to make it easier to handle. The DNA bands on gel transfer to nylon 5. MAKING IT PERMANENT B) TAGGING THE FRAGMENTS WITH A DNA PROBE The bands of DNA are made visible using probes (aka radioisotopes), radioactive element chemicals that attach to the specific segment w/in each band of DNA on the nylon membrane 5. MAKING IT PERMANENT C) VISUALIZING THE FRAGMENTS THROUGH AUTORADIOGRAPHY ‐ Tech places nylon between 2 sheets of x‐ray film in order to make an autoradiograph (autorad). The radioisotope‐tagged DNA bands on nylon are exposed to the film, making a pattern on the film. C:..ll!r:::iilJ��..iE.�-=--=-=-��-=....:::::;Б.�-=-=--=---=�-=::=:-_..-::-�=--�;::...�::-=:��=-===z=�-==�===:;;___.c;;..;.;;;..___-----""'------------= § TJ1e result s of а DNA fingerprrnt analysrs.