Gene Technolgy My Science Corner基因技术我的科学角.ppt

Gene Technology I. DNA Identification Humans are not genetically alike, except for twins 0.10 % of human genome is different from person to person DNA ID compares samples in regions of a chromosome that differ Paternity, ID human remains, tracing human origins, forensic Non-coding DNA Do not code for proteins Length polymorphisms Variations in the length of the DNA molecule between known genes Variable number tandem repeats (VNTR) Repeating sequences on “behind” the other CACACA Number of VNTR at specific loci (places) varies among individuals Each VNTR has specific number of repeats Steps in DNA ID Copying DNA : Polymerase Chain Reaction (PCR) Cutting DNA: Restriction enzymes Sorting DNA by Size: Gel Electrophoresis Copying DNA : PCR Template DNA Add DNA polymerase (Taq polymerase) Free nucleotides Primers Heat DNA strands separate Cool – allows primers bind to original DNA DNA polymerase adds free nucleotides Heat again to repeat the process Cutting DNA: Restriction Enzymes Made from bacterial proteins Named after the bacteria they were are from Cuts specific DNA sequences Sorting DNA: Gel Electrophoresis Cut DNA with restriction enzymes Run restriction fragments Shorter fragments run faster Transfer DNA to nylon membrane Add radioactive probes that bind to complementary DNA Expose X-ray film to radio-labeled membrane Pattern of bands the DNA fingerprint Accuracy of DNA Fingerprints DNA fingerprinting compares five to thirteen VNTR loci Thirteen loci produce odds that two people will share a DNA profile at about one in 100 billion Remember: 6.5 billion people on earth II. Recombinant DNA Combining DNA from two individuals Genetic engineering Process of altering the genetic material of cells or organisms to allow them to make new subtances Clones Exact copy of DNA segment, a whole cell, or a complete organisms Vectors Usually bacterium or yeast; carries foreign DNA Steps in making recombinant DNA Isolate DNA plasmid and gene of interest Plasmid Smal