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DNA Technology
• Terminology
• USES of DNA technology
• DNA fingerprinting
• protein production
• gene therapy
• GMO - Genetically Modified Organisms
• cloning
• Stem Cells
• Genetic Counseling
Nucleic Acids: DNA & RNA - review• DNA
• deoxyribonucleic acid
• w/in DNA
• genes: specific locations in DNA that codes for proteins or traits
• program the production of proteins
• determines traits for organisms
• RNA
• helps in translating code
DNA & RNA - monomers:
nucleotides
• sugar
• DNA - deoxyribose
• RNA - ribose
• phosphate group
• nitrogenous bases
• DNA --
• adenine (A); thymine (T); cytosine (C); and guanine (G)
• RNA --
• same, except uracil (U) instead of thymine
fig 3.6b
Closer Look at DNA molecule - string of nucleotides:
• backbone of sugar & phosphate
• deoxyribose
• four bases
• A, T, G, C
• double helix
• twisted double stranded molecule
•DNA gene sequence •mRNA & tRNA work together to determine • 3-base codons code for specific amino acids
• sequence of amino acids determine specific proteins
How does proteins affect observable traits of organisms?
Example: eye color in fruit flies
• normal gene codes for red eyes
• Mutations code for brown or white
Restriction Enzyme
• cut DNA in specific spots depending on the code in the enzyme
Bacterial Vectors
• Bacteria used to carry pieces of genetic information from other organisms
• plasmids – ring shaped DNA
• Recombinant DNA
• Bacterial plasmid and inserted gene
DNA Technology - Terminology:DNA Technology - Terminology:
Forming Recombinant DNA using Restriction Enzymes:
• cut DNA at specific sequences creating fragments
• addition of DNA from other source
• new DNA fragment created
• joined by ligase
(1) DNA fingerprinting(1) DNA fingerprinting
• Extract a sample of DNA
• break cell & nuclear membranes
• cut DNA with restriction enzymes
• separate DNA fragments using electrophoresis
•Make DNA visible by staining and attaching to radioactive markers
Uses of DNA technology:Uses of DNA technology:
fig 11.2
• DNA is a negatively charged molecule
• placing it on a special liquid gel and running current through the gel will cause DNA to move from negative pole to positive pole
• the large fragments move the least
•Smaller fragments move the farthest
Gel Electrophoresis:Gel Electrophoresis:
fig 11.2
(2) Protein production(2) Protein productionUses of DNA technology:Uses of DNA technology:
• use of microbes & cultured cells
• open plasmid and insert human gene (use restriction enzymes)
•transfer back into bacteria
• bacterial clones grown
• protein can then be harvested
fig 11.12
(3) Gene Therapy(3) Gene TherapyUses of DNA technology:Uses of DNA technology:
•infant has defective gene which causes cells to not function normally
• insert normal gene for the child’s defective gene into a virus
• use the virus to insert the normal gene into defective stem cell
• grow the genetically altered stem cells and then insert them back into the infant
fig 11.19
• bone marrow stem cells have potential to develop into different blood / immune cells
(4) Genetically (4) Genetically Modified OrganismsModified Organisms
Uses of DNA technology:Uses of DNA technology:
• use recombinant DNA to produce organisms with new traits
• examples
• btCorn (resistant to corn borer)
• golden rice (increase of Vitamin A production)
(4) Cloning(4) CloningUses of DNA technology:Uses of DNA technology:
• clone: genetic replica
• reproductive cloning
• transfer of a nucleus from a donor adult cell (somatic cell) to an egg which has no nucleus
• therapeutic cloning
• cells that are created through cloning are permitted to divide repeatedly to form a blastocyst.
•extract stem cells from the blastocyst
• use those cells to grow tissue that are a perfect genetic match for the patient. fig 11.17
Stem Cell categories
•Totipotent– ability of a single cell to divide and produce all the differentiated cells in an organism – including extraembryonic tissues (placenta)
•Pluripotent•potential to differentiate into any of the three germ layers: endoderm, mesoderm, or ectoderm •Embryonic Stem cells (ES cells)
–derived from embryos that develop from eggs that have been fertilized in vitro
–Embryonic Germ cells (EG cells)–precursors of the gametes.
• Multipotent–can give rise to several other cell types, but those types are limited in number.
• Unipotent– capacity to develop/differentiate into only one type of tissue/cell type
Stem Cell categories
Genetic Counseling:
• Genes for particular disorders are known
• may be markers that can be tested for
• determine probability of offspring contracting the disease
Huntington’s Disease
•4 million bases on the fourth chromosome
• Breast Cancer
• located on the long arm of chromosome 6. Women with this marker are 1.4 times as likely to get breast cancer.
Genetic Testing // IVF Genetic Screening
• pedigree analysis or direct genetic testing available for Cystic Fibrosis
• parents with a family history of Cystic Fibrosis can screen embryos for the disorder PRIOR to in vitro fertilization
• • fertilization occurs
• single cell removed
• embryos
• first child as the result of this screening born in 1990