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DNA Technologies. Recombinant DNA methods Restriction enzymes Enzymes from bacteria Used to cut DNA molecules in specific places Enable researchers to cut DNA into manageable segments Vector molecule carrier of DNA fragment into cell Transformation: uptake of foreign DNA into cells.
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Recombinant DNA methods • Restriction enzymes • Enzymes from bacteria • Used to cut DNA molecules in specific places • Enable researchers to cut DNA into manageable segments • Vector molecule carrier of DNA fragment into cell • Transformation: uptake of foreign DNA into cells
Splicing foreign DNA into a vector • Foreign DNA and plasmid DNA cut with same restriction enzyme • Produces linear molecules with complementary single-stranded ends • Recombinant DNA created by mixing so sticky ends pair • DNA ligase forms covalent bonds, linking the two fragments
Genomic library • Collection of DNA fragments that represent all the DNA in the genome • Chromosome library • All the DNA fragments in that specific chromosome • cDNA library • Produced using reverse transcriptase • Makes DNA copies of mature mRNA
Genetic probes • Segments of single-stranded DNA that can hybridize to complementary base sequences in target gene • Southern blot technique
Using a geneticprobe to find bacterial cellswith a specificrecombinant DNA molecule
Amplifying DNA in vitro by PCR • Small amount of double-stranded DNA • DNA precursors • Specific nucleic acid primers • Taq DNA polymerase • DNA is denatured • Primers attach to primer-binding site on each DNA strand • Each strand acts as template for DNA synthesis
DNA sequencing • Based on chain termination method • Yields information about • Structure of gene • Probable amino acid sequences of its encoded proteins
Applications of DNA technology • Gene therapy • Tissue engineering • DNA typing
Transgenic organisms • Foreign DNA incorporated into their genetic material • Gene target • Single gene inactivated or “knocked out” • “Knockout mice” used in studying genes • Mutagenesis screening • Male mice treated with mutagens and studied
A transgenicmouse Mouse on rightis normal; mouseon left is transgenic animal expressing rat growth hormone
Transgenicrice “Golden rice”shown intermixedwith white ricecontain highconcentrationsof beta-carotene
Safety guidelines • Safety concerns • Introduction of transgenic organisms into the environment • Health effects on humans from consuming GM crops • Safety measures • Special facilities designed to hold pathogenic organisms • Science of risk assessment