DNA Technology Terminology USES of DNA technology DNA

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

fig 3. 6 b 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

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

Base Pairing: • AT/GC rule – A with T – G with C • 2 DNA strands are complementary fig 11. 11

• DNA gene sequence • m. RNA & t. RNA 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

DNA Technology - Terminology: 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

Restriction Enzymes: • cut DNA • enzymes • cut at specific base sequence

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

Making “customized” bacteria

Uses of DNA technology: (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 fig 11. 2

Gel Electrophoresis: • 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 fig 11. 2

Reading the gels: fig 11. 5

Uses of DNA technology: (2) Protein production • 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

Uses of DNA technology: (3) Gene Therapy • 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 • bone marrow stem cells have potential to develop into different blood / immune cells fig 11. 19

Uses of DNA technology: (4) Genetically Modified Organisms • use recombinant DNA to produce organisms with new traits • examples • bt. Corn (resistant to corn borer) • golden rice (increase of Vitamin A production)

Uses of DNA technology: • clone: genetic replica (4) Cloning • 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.

Stem Cell categories • 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

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