SC-100: Class 26Science of Life • Genetic Engineering • DNA Fingerprinting • Viruses • Gene Therapy • DNA Repair • HIV
Genetic Engineering • Procedure by which foreign genes are inserted into an organism, or existing genes are altered, to modify the functions of that organism.
Strategy • “Restriction” enzymes cut DNA molecules, exposing certain regions of unattached bases • If the cut regions of two different DNA molecules are “complementary”, they can be put together and the bases will bind. • If the new stretch is a gene, it will be produced in the original cell.
DNA Fingerprinting • Compares “Variable Number Tandem Repeats” (VNTR) (nonsense phrases, mostly STOP codes leading to no protein manufacture) in DNA of two samples • Segments of DNA containing VNTR are spread out by electrophoresis according to size. • The pattern is made visible and recorded. • Each individual’s DNA has a different pattern.
Genome Project • The Genome Project was started in 1990 and completed in 2003. Genome is the name for ALL of the DNA in an organism. The DNA in humans is organized into 24 chromosomes; each chromosome contains many genes; the genes contain many base pairs. The purpose of the Project was to determine the location of the genes in the human chromosomes and the base pair sequence within the genes.
Viruses • A short lengrth of RNA or DNA wrapped in a protein coating that fits cell receptors and replicates itself by using the cell’s machinery. • Viral DNA may produce mRNA or • Viral RNA may serve as mRNA or • Viral RNA is transcribed to DNA and spliced into cell’s DNA
Gene Therapy • Some genetic diseases occur because a specific protein is not being made in an individual’s cells due to a defective gene (each gene makes a specific protein). • “Good” viruses: Modified virus that can insert a desired gene into a cell.
DNA Repair • Whenever DNA replicates, a certain amount of damage, from the environment or metabolic byproducts, occurs. • One base substituted for another.: “point defect” • Mismatch: two bases attached to one on other strand • Enzymes correct mistakes.
Human Immunodeficiency Virus - HIV • Invades white blood cells • HIV genetic material is RNA • HIV Protein coat contains enzymes to cause “reverse transcription” of RNA into DNA. • More enzymes place this into cell’s DNA. • Cell now makes HIV. • Transcription is “noisy” causing mutations that make new strains of the HIV.