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

Cutting DNA with a restriction enzyme

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

Plasmids

Genomic library Chromosome library cDNA 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

Producing a genomic or chromosome library

Genetic probes Segments of single-stranded DNA that can hybridize to complementary base sequences in target gene Southern blot technique

Using a genetic probe to find bacterial cells with a specific recombinant 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

Amplification of DNA by PCR

DNA sequencing Based on chain termination method Yields information about Structure of gene Probable amino acid sequences of its encoded proteins

Chain termination method of DNA sequencing

Applications of DNA technology Gene therapy Tissue engineering DNA typing

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 transgenic mouse Mouse on right is normal; mouse on left is transgenic animal expressing rat growth hormone

Transgenic rice “Golden rice” shown intermixed with white rice contain high concentrations of beta-carotene

Safety guidelines Safety concerns Safety measures 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