Golden Rice or Frankenfood Scientists transferred daffodil genes

Golden Rice or Frankenfood? • Scientists transferred daffodil genes into rice • Rice with beta-carotene may help prevent vitamin A deficiencies • Opponents fear unforeseen consequences of creating genetically modified organisms

Genetic Changes • Humans have changed the genetics of other species for thousands of years – Artificial selection of plants and animals • Natural processes also at work – Mutation, crossing over

Genetic Engineering • Genes are isolated, modified, and inserted into an organism • Made possible by recombinant DNA technology – Cut up DNA and recombine pieces – Amplify modified pieces

Discovery of Restriction Enzymes • Hamilton Smith studied how bacterium Haemophilus influenzae cut invading viral DNA • Discovered that bacteria have an enzyme that chops up viral DNA

Specific Cuts • Restriction enzymes cut DNA at a specific nucleotide sequence • Cuts leave “sticky ends” on DNA fragments that pair with matching cuts

Making Recombinant DNA 5’ G A A T T C 3’ C T T A A G one DNA fragment another DNA fragment 5’ G A A T T C 3’ 3’ C T T A A 5’ G

Making Recombinant DNA nick 5’ G A A T T C 3’ 3’ C 5’ T T A A G nick DNA ligase action G A A T T C C T T A AG

Using Plasmids • Plasmid: a small circle of bacterial DNA • Foreign DNA inserted into plasmid – is replicated and distributed along with plasmid • Plasmid becomes a cloning vector – delivers DNA into another cell

Cloning Vectors

Using Plasmids a A restriction enzyme cuts a specific base sequence everywhere it occurs in DNA. c The same enzyme cuts the same sequence in plasmid DNA. b The DNA fragments have sticky ends. e The DNA fragments and plasmid DNA are mixed with DNA ligase. f The result? A collection of recombinant plasmids that incorporate foreign DNA fragments. d The plasmid DNA also has sticky ends g Host cells that can divide rapidly take up the recombinant plasmids. Fig. 11 -3, p. 164

Gene Libraries • Cells that host fragments of cloned DNA – Genomic library

Where am I? 1. 2. 3. 4. 5. 123 Devilbiss Biology 101 SU US Earth

DNA Sequencing • Order of fluorescent bands indicates DNA sequence

Polymerase Chain Reaction • Sequence to be copied is heated • Primers are added and bind to ends of single strands • DNA polymerase uses free nucleotides to create complementary strands • Doubles number of copies of DNA

Polymerase Chain Reaction double-stranded DNA to copy DNA heated to 90°– 94°C primers added to base-pair with ends mixture cooled; base-pairing of primers and ends of DNA strands DNA polymerases assemble new DNA strands

Polymerase Chain Reaction mixture heated again; makes all DNA fragments unwind mixture cooled; basepairing between primers and ends of single DNA strands DNA polymerase action again doubles number of identical DNA fragments

DNA Fingerprints • Unique array of DNA fragments • Inherited from parents in Mendelian fashion • Even full siblings can be distinguished from one another by this technique

Analyzing DNA Fingerprints • DNA is separated by gel electrophoresis • Pattern of bands is used to – Identify or rule out criminal suspects – Identify bodies – Determine paternity

A DNA Fingerprint

DNA Sequence Data • Evolutionary trends • Potential therapies for genetic diseases • Data bases using computer technology

Genetics in Practice • Genetic engineering is used to change genetic makeup of organisms – Genes transferred between species (Transgenic organisms) – Genes modified and reinserted into same species

Transgenic Plants • Contain DNA from another species • New genes make crop plants less vulnerable to disease and pests • Use bacterial cloning vectors to insert foreign gene (Ti plasmid)

Transgenic Cotton • Resistant to herbicides • Insecticide gene

Genetically Engineered Bacteria • Produce medically valuable proteins • Breakdown environmental contaminants • Designed to survive only under narrow conditions

Transgenic Animals • Early experiments in mice – Injection of rat gene corrected a growthhormone deficiency – Injection of human growth-hormone gene produced giant mice • Human genes are now routinely transferred into animals to produce human proteins for use as drugs

Genetically Modified Animals

Gene Therapy For SCID-X 1 • Designed to cure “bubble babies” – Immune system can’t fight infection

Gene Therapy For SCID-X 1 • Retrovirus inserts normal allele into cultured stem cells • Modified stem cells returned to child’s bone marrow • Successfully created immune function • Also caused leukemia in some children

Who Gets Enhanced? • Eugenic engineering – Selecting for “desirable” human traits • How should we use gene therapy? • Who should decide what genetic traits can or should be altered?

Xenotransplantation • Human organs are in short supply • Pig organs are similar, but human body rejects them as foreign • Scientists work to knockout pig genes that trigger rejection • Can interspecies transplants introduce new diseases to humans?

“Frankenfood” • Genetically engineered foods are widespread in the US • Cut costs, reduce herbicide use, enhance yields • What effect will they have on humans and ecosystems?

Transgenic Mouse • With genes for fluorescent protein