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DNA Technology
Chapter 12
Transgenic Organisms
• Contain recombinant DNA
– Nucleotide sequences from 2+ different sources
• Cells express original AND newly introduced
genes
– Mitosis ensures all daughter cells contain (growth
and plant reproduction)
– Injection into gametes or zygote necessary for most
animals
• Spectrum of views for applicability
Producing Recombinant DNA
• Desired gene is removed from source
(plant, animal, bacteria)
• Plasmids used as vectors
• Restriction enzyme cuts gene and
plasmid
– Plasmid in1 spot only, DNA in many
– ‘Sticky ends’ allow complementary binding
when same enzyme used
• DNA ligase joins
• Recombinant DNA inserted into a cell
– Mitosis produces clones
DNA Fingerprinting
• A way to identify an individual based on their
unique sequences of DNA
• Many sequences are the same in humans
• Look for regions with greatest diversity
(polymorphisms)
– Often are noncoding (intron) regions
– Short tandem repeats (STRs) used now
• 4 nucleotide sequences
• Vary in length between individuals
• Try to look at enough to eliminate everyone else
– More STRs used increase uniqueness
Analyzing DNA Fingerprints
• Polymerase chain reactions (PCR) to
amplify DNA
– Evidence is often scarce or
contaminated/impure
– Allows controlled testing
• Restriction enzymes cut out desired
sequences
• Gel electrophoresis sorts molecules by size
– PO4- attracted to positive charged end
– Smaller fragments move faster and farter
– Compare lanes for similarities/differences
• Used to solve crimes, paternity testing,
inheritance
CODIS
• Combined DNA Index System
• Allows comparison of DNA samples between individuals
– Database managed by the FBI
• Based on 14 predetermined STRs
– 13 on 13 different autosomes
– 1 on X and Y chromosome
Human Genome Project (HGP)
• Sequenced entire genome
– Started in 1990 finished in 2006
– Gov’t agencies started, private company joined
– Separated over data release policy
• Publically available components via internet at Genbank
– 3.2 billion base pairs
• 1.5% coding
• 98.5% noncoding
• 96% similarity with chimpanzees
– Gene expression allows few genes to code for many RNA’s
• Reference genome is diverse mix of anonymous donors