NOTES - CH 15 (and 14.3): DNA Technology ( Biotech )

NOTES - CH 15 (and 14.3): DNA Technology ( Biotech )

Vocabulary Genetic Engineering Gene Recombinant DNA Transgenic Restriction Enzymes Vectors Plasmids Cloning Key Concepts What is genetic engineering? How do scientists use it?

BIOTECHNOLOGY: the use of living organisms or their components to do practical tasks TRADITIONAL BIOTECH: -microorganisms to make wine / cheese -selective breeding of livestock -production of antibiotics

**Practical goal of biotech = improvement of human health and food production

DNA Technologies: 1) Making a recombinant DNA molecule; 2) Gene therapy; 3) DNA fingerprinting; 4) Cloning.

Recombinant DNA: Combining fragments of DNA from different sources; Result: organisms with their DNA + foreign DNA such organisms are known as: TRANSGENIC ORGANISMS.

Example of transgenic organism: Tobacco plant that contains a gene from a firefly it glows!

BIOLUMINESCENT CAT!

Toolkit for recombinant DNA technology involves: -restriction enzymes -DNA vectors -host organisms

RESTRICTION ENZYMES = enzymes that recognize and cut short, specific DNA sequences

Restriction Enzymes are used to cut out a specific DNA fragment from an organism s genome; recognize sequences that are palindromic (the same letters backward and forward); typically cut sequences in a staggered manner so that the two ends of the fragments are single-stranded;

Restriction Enzymes (cont.) this creates sticky ends so that the DNA fragment from one organism will be complementary to the DNA fragment from another organism. (complementary base pairing)

Gene Splicing: GENE SPLICING = rejoining of DNA fragments after cutting with restriction enzymes foreign DNA is recombined into a bacterial plasmid or viral DNA

VECTORS = carriers for moving DNA from test tubes back into cells -bacterial plasmids (small, circular DNA molecules that replicate within bacterial cells) -viruses

HOST ORGANISMS: bacteria are commonly used as hosts in genetic engineering because: bacterial cells are simple, and grow quickly, replicating and expressing any foreign genes they carry.

Once the foreign DNA has been transferred into the host bacterial cell, it replicates every time the cell divides; CLONES = genetically identical copies of a gene Gene Cloning:

Gene Expression: In addition to copying the introduced foreign gene, bacterial cells will also EXPRESS the genes (make the protein the gene encodes!) EXAMPLE: if the gene for human insulin is EXAMPLE: if the gene for human insulin is inserted into a bacterial plasmid and then into a host bacterial cell, that cell will start to make HUMAN INSULIN!

Steps Involved in Cloning a Human Gene: 1) Isolate human gene to clone; 2) Isolate plasmid from bacterial cell; plasmid Human gene 3) Add a restriction enzyme to cut out human gene & add same R.E. to open up bacterial plasmid (creates complementary sticky ends ); 4) Combine human gene with bacterial plasmid;

Cloning a Human Gene (cont.) 5) Insert recombinant DNA plasmid back into bacterial cell; 6) As bacterial cell reproduces, it makes copies of the desired gene and expresses that gene (makes whatever protein the gene encodes)!

Applications of DNA Technology: Recombinant bacteria in industry; Recombinant bacteria in medicine; Recombinant bacteria in agriculture; Transgenic animals; Transgenic plants.

Recombinant bacteria in Bacteria that can: industry: break down pollutants; degrade oil spills; extract minerals from ores.

Recombinant bacteria in medicine: Bacteria that have received human genes and produce: human growth hormone; insulin to treat diabetes; the amino acid phenylalanine.

Recombinant bacteria in Bacteria that: agriculture: protect crops against frost; produce natural fertilizers; prevent crops from spoiling after harvest.

Transgenic animals: Engineer / produce animals with human diseases so that they can be studied in detail.

Transgenic plants: Plants that are engineered to: resist herbicides; produce internal pesticides; increase protein production.

Other DNA Technologies: Polymerase Chain Reaction (PCR); Human Genome Project; Gel Electrophoresis; Gene Therapy; DNA Fingerprinting

The Polymerase Chain Reaction (PCR) allows any piece of DNA to be quickly copied many times in the lab;

PCR (continued) BILLIONS of copies of DNA are produced in just a few hours (enough to use for testing); In 6 cycles of PCR: cycle 1: 2 copies cycle 2: 4 copies cycle 3: 8 copies cycle 4: 16 copies cycle 5: 32 copies cycle 6: 64 copies cycle 20: 1,048,576!!

Polymerase Chain Reaction (PCR) PCR is highly specific; only a small sequence is amplified only tiny amounts of DNA are needed.

Starting materials for PCR: DNA to be copied Nucleotides (A,G,C,T) Primers DNA polymerase

Applications of PCR: analyze DNA from tiny amounts of tissue or semen found at crime scene; analyze DNA from single embryonic cells for prenatal diagnosis; analyze DNA or viral genes from cells infected with difficult to detect viruses such as HIV; used extensively in Human Genome Project (14.3)

PCR works like a copying machine for DNA!

Analysis of Cloned DNA: Gel electrophoresis separates DNA molecules based on SIZE a mixture of DNA fragments will be sorted into bands, each consisting of DNA molecules of the same length YOUR DNA MY DNA

Steps Involved in DNA Fingerprinting: 1) Collect DNA from a sample; 2) Perform PCR if necessary to make more DNA; 3) Cut DNA apart using RE s **Junk DNA (introns) will be cut at different places for different people, therefore producing different size fragments

DNA Fingerprinting (cont.) 4) Electrophoresis is used to separate DNA pieces on a gel to create a banding pattern; 5) Photo of DNA gel is taken as evidence; 6) Banding patterns can then be compared.

Sample 1 Sample 2 DNA_DetectivePC.exe

Gene Therapy: GENE THERAPY = the insertion of normal genes into human cells to correct genetic disorders Diseases treated include: cystic fibrosis SCID (immune deficiency)

Biotech Today & Tomorrow Experimental Ethical issues Research funding Who can afford treatment?