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

Base Pairing: • AT/GC rule

– A with T

– G with C

• 2 DNA strands are complementary

fig 11.11

•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:

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

(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

Reading the gels:Reading the gels:

fig 11.5

(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