Biotechnology Mader 19.4

Restriction Enzymes- Cut and paste DNA

Cloning a gene

Making Transgenic Animals

Transgenic corn makes bacterial toxin that kills corn borers

PCR Can Amplify Minute Amounts of specific DNA segmemts.

DNA Profiling Some of the non coding DNA in genomes is found as short tandem repeated sequences called microsatilites. A given tandem repeat will be flanked on either end by a “target” sequence In different individuals the number of repeats between targets varies (alleles)

PCR Products are analyzed by gel electrophoresis Using the same primer we can detect several repeat number alleles. L S

DNA profiling using microsatellite markers DNA fingerprinting/profiling is a powerful method of determining the genetic identity of a single person. Since every individual's DNA is unique, with the exception of identical twins, DNA testing can be the key in solving criminal cases by conclusively identifying an individual through biological evidence found at the scene. Using 13 markers, the average probability that two individuals selected at random have an identical DNA profile is approximately 1800 trillion to 1 for African-Americans and approximately 380 trillion to 1 for U.S. Caucasians. Theoretically, this means that, with the exception of identical twins, no two individuals in the world should have identical DNA profiles.

How Does The DNA Test Work in Forensic/Non-Forensic Cases? Specimens collected from the crime scene(s) and suspect(s) are analyzed using 13 DNA microsatellite markers. The DNA profile obtained from the crime scene is compared with the DNA profile from the suspect. If both DNA profiles are identical, then it is determined to be a match and a random match probability is calculated. The random match probability is the chance that another, unrelated, individual would also match the obtained DNA profile. If there are any differences between the DNA profile obtained from the crime scene and the suspected individual then it is concluded that the crime scene sample did not come from the suspect.

Testing paternity with microsatelite markers The mother's (M) microsatellite markers are shown in blue. Both children have one copy of the microsatellite marker (blue) that is the same size as one of the mother's. This copy of the marker was passed on from mother to child. The children's other copy, shown in red, was inherited from alleged father 1 (F1). Both copies of the second alleged father's marker (F2), shown in green, are completely different in size from the children's blue and red copies. This means that alleged father 2 (F2) is not the biological father of either child. Therefore, alleged father 1 (F1) is the biological father of both children and alleged father 2 (F2) is not the biological father of either child. M = Mother, C1-2 = Two Children, F1-2 = Two Alleged Fathers