Class Notes and Handouts for
Plant Biology 102

Plants, People and the Environment

Links of the Day:

Lecture 19. New and better: Recombinant DNA and genetic engineering.

Barbara McClintock was one of the pioneers in discovering how changes in DNA affect the physical traits of organisms. She was awarded a Nobel Prize in 1983 for her work on "jumping genes" or transposable elements. Here are several links for you to explore to learn more about the life and career of this remarkable scientist: Barbara McClintock, Barbara McClintock (1902-1992) (from Access Excellence Website), Barbara McClintock (from Cold Spring Harbor Laboratory Website), A celebration of the life of Barbara McClintock (a summary of the memorial service held for Dr. McClintock).

The techniques available for manipulating DNA include the use of restriction enzymes to cut double-stranded DNA, cloning of DNA fragments into bacterial plasmids, and amplification of selected regions of DNA through the polymerase chain reaction (PCR). The links included in today's update have good illustrations and/or explanations of the techniques I mentioned in class.

For information about how restriction enzymes work try these sites: Restriction enzymes, and Restriction enzyme activity of EcoRI.

For information about cloning DNA and making a DNA library follow these links: Insertion of a DNA sample into a plasmid, Plasmid insertion, and Transfer and cloning of the insulin gene.

Here are some web pages that explain PCR: What the heck is PCR?, and Polymerase Chain Reaction (PCR) (a diagram).

Applications for PCR include DNA sequencing, diagnosis of disease and identification of organisms by their genetic fingerprints, identification of DNA fingerprints for use in criminal cases, and many other types of studies about populations of plants and animals. I'm including some sites of general interest on ancient DNA and forensic uses of PCR technology.

For ancient DNA: The science of amber, Amber, insects, and fossils, Ancient nucleic acids from insects, "Jurassic Park" bacterium!, and Genetic archaeology (not about ancient DNA per se, but how scientists use DNA sequences to reconstruct the evolutionary histories of organisms such as humans).

For forensic uses, including paternity testing: Helix Biotech, Inc. Homepage (a commercial firm specializing in criminal forensic and paternity testing), DNA evidence in the courtroom (a thorough article written by a law firm, which explains the positive and negative aspects of using forensic DNA evidence in criminal cases -- this is definitely worth reading), Explanation DNA paternity test, DNA paternity test services (a commercial service site with some background information on paternity testing).

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Last updated February 9, 1999.