Chapter 19 DNA Technology

Genetic Engineering Genetic engineering Genetic engineering the manipulation of genetic material for practical purposes the manipulation of genetic material for practical purposes Biotechnology Biotechnology the manipulation of living organisms or their components to perform practical tasks or provide useful products the manipulation of living organisms or their components to perform practical tasks or provide useful products

Recombinant DNA Recombinant DNA contains DNA from 2 sources Recombinant DNA contains DNA from 2 sources Basic Breakdown Basic Breakdown Plasmids are isolated from bacterial cells Plasmids are isolated from bacterial cells Foreign genes are inserted into the isolated plasmids Foreign genes are inserted into the isolated plasmids Plasmids are then returned to bacterial cells, which reproduce Plasmids are then returned to bacterial cells, which reproduce This clones the recombinant DNA This clones the recombinant DNA

Restriction Enzymes Enzymes that cut up foreign DNA (a process known as restriction) Enzymes that cut up foreign DNA (a process known as restriction) REs are very specific – REs are very specific – they look for a certain nucleotide sequence in DNA and cut it at precise locations they look for a certain nucleotide sequence in DNA and cut it at precise locations The resulting DNA fragments are known as restriction fragments The resulting DNA fragments are known as restriction fragments The single-stranded ends are known as sticky ends The single-stranded ends are known as sticky ends

Restriction Enzymes The sticky ends can be used to join DNA pieces from different sources The sticky ends can be used to join DNA pieces from different sources DNA ligase can be used to make the fusion “permanent” DNA ligase can be used to make the fusion “permanent” The DNA now is known as recombinant DNA – DNA from different sources The DNA now is known as recombinant DNA – DNA from different sources

Vectors Vectors are used as carriers to transport engineered DNA from a test tube into a cell Vectors are used as carriers to transport engineered DNA from a test tube into a cell Most common vectors: Most common vectors: bacterial plasmids and viruses bacterial plasmids and viruses As plasmids or viruses reproduce, they replicate the engineered DNA As plasmids or viruses reproduce, they replicate the engineered DNA

Gel Electrophoresis Electrophoresis separates macromolecules (either proteins or nucleic acids) on the basis of size, electrical charge, and other physical properties Electrophoresis separates macromolecules (either proteins or nucleic acids) on the basis of size, electrical charge, and other physical properties After DNA has been cut into fragments by restriction enzymes, it is loaded into a gel and electricity is applied After DNA has been cut into fragments by restriction enzymes, it is loaded into a gel and electricity is applied Shorter fragments travel farther than longer ones Shorter fragments travel farther than longer ones Used to match up criminals with crime scene evidence… and lots of other things too! Used to match up criminals with crime scene evidence… and lots of other things too!

Gel Electrophoresis

Polymerase Chain Reaction (PCR) A technique by which any piece of DNA can be quickly amplified (copied many times) in vitro A technique by which any piece of DNA can be quickly amplified (copied many times) in vitro DNA is incubated with DNA polymerase and primers, causing DNA replication to occur DNA is incubated with DNA polymerase and primers, causing DNA replication to occur

Commercial Applications of PCR PCR has many commercial applications: PCR has many commercial applications: Amplify DNA from tiny amounts of blood, tissue, or semen found at crime scenes Amplify DNA from tiny amounts of blood, tissue, or semen found at crime scenes Amplify DNA from single embryonic cells for rapid prenatal diagnosis of genetic disorders Amplify DNA from single embryonic cells for rapid prenatal diagnosis of genetic disorders Amplify DNA of viral genes from cells infected with difficult-to-detect viruses as HIV and HPV Amplify DNA of viral genes from cells infected with difficult-to-detect viruses as HIV and HPV And More! And More!

PCR

Gene Therapy Genetic engineering has the potential to actually correct some genetic disorders in individuals Genetic engineering has the potential to actually correct some genetic disorders in individuals For genetic disorders traceable to a single defective allele, it should be possible to replace the defective allele with a functional one using recombinant DNA For genetic disorders traceable to a single defective allele, it should be possible to replace the defective allele with a functional one using recombinant DNA Somatic cells/germ cells/embryonic cells Somatic cells/germ cells/embryonic cells

Gene Therapy Genetic engineering has the potential to actually correct some genetic disorders in individuals Genetic engineering has the potential to actually correct some genetic disorders in individuals For genetic disorders traceable to a single defective allele, it should be possible to replace the defective allele with a functional one using recombinant DNA For genetic disorders traceable to a single defective allele, it should be possible to replace the defective allele with a functional one using recombinant DNA Somatic cells/germ cells/embryonic cells Somatic cells/germ cells/embryonic cells Ethical questions… Ethical questions…

Gene Therapy

A Few Applications of DNA Technology Forensics Forensics DNA testing at crime scenes DNA testing at crime scenes Legal cases: 1/100,000 – 1/1,000,000,000 Legal cases: 1/100,000 – 1/1,000,000,000 “DNA Fingerprinting” “DNA Fingerprinting” Environmental Environmental Engineering microorganisms to transform chemicals/deal with environmental problems Engineering microorganisms to transform chemicals/deal with environmental problems Detoxifying specific toxic wastes in spills, etc. Detoxifying specific toxic wastes in spills, etc.

A Few Applications of DNA Technology Agricultural: Agricultural: Transgenic organisms Transgenic organisms FlavrSavr tomato FlavrSavr tomato Insect-resistant plants, viral-resistant plants… Insect-resistant plants, viral-resistant plants…

Ethical Questions Short-term/long-term side effects Short-term/long-term side effects Vaccines, drugs, etc. Vaccines, drugs, etc. Genetically-engineered agricultural products: Genetically-engineered agricultural products: Introducing new organisms to the environment Introducing new organisms to the environment Ecological effects Ecological effects Genetically engineered “superweeds” Genetically engineered “superweeds” Human Genome Project Human Genome Project Gene therapy implications Gene therapy implications Ownership Ownership