DNA Technology Biology 6(H)

Learning Objectives Describe common DNA technology techniques Identify how each technique is used to study or manipulate the genomes of organisms DNA Technology

Development has launched a revolution in biotechnology Examples of DNA technology techniques: – Chromosomal analysis – DNA fingerprinting – Genetic modifications DNA Technology

Chromosomal analysis – procedure used to determine chromosomal abnormalities Karyotype – photograph of arranged chromosomes from cell – Amniocentesis – procedure to obtain a sample of amniotic fluid containing fetal cells Comparison of patient karyotype to normal human karyotype Chromosomal Analysis

What can be determined by chromosomal analysis? Sex of fetus – XX – female – XY – male Chromosomal Analysis

What can be determined by chromosomal analysis? Missing or extra chromosomes – Down syndrome – extra chromosome 21 – Klinefelter’s syndrome – extra X chromosome (XXY) – Turner syndrome – missing X chromosome (X--) Chromosomal Analysis

DNA fingerprinting – technique that uses the pattern of DNA fragments caused by specific enzymes to identify individual organisms Procedure: 1.DNA samples taken from individuals 2.DNA separated from cells and cut into segments by restriction enzymes 3.Cut DNA run through gel electrophoresis and samples compared DNA Fingerprinting Image by Rkalendar (Own work) [CC-BY-SA-3.0]

Gel electrophoresis – apparatus used to separate DNA segments based on their size Procedure: – DNA samples are loaded at top of a gel – Electric current ran through gel – DNA segments travel from negative to positive end of gel – DNA segments separate into bands according to their size Gel Electrophoresis

What is DNA fingerprinting used for? Criminal investigations – Compare crime scene DNA to suspect DNA Paternity testing – Compare child’s DNA to possible father’s DNA Identifying dead person’s remains – Compare relatives’ DNA to remains’ DNA Studying ecology and evolution – Similarities in DNA of species show common descent DNA Fingerprinting Image by Magnus Manske (Own work) [CC-BY-SA-3.0]

Genetic engineering – direct manipulation of genes for practical scientific or medical purposes Examples: – Cloning – Gene mapping Genetic Modifications

Cloning – process used to make multiple copies of a desired gene Performed using: – Plasmids – circular segments of DNA normally found in bacteria – Recombinant DNA – altered DNA using genetic material from different species Cloning

1.DNA containing desired gene is isolated from organism a.Restriction enzymes cut DNA around desired gene b.Multiple copies of desired gene made using polymerase chain reaction (PCR) 2.Gene copies are inserted into plasmids a.DNA ligase enzyme binds two types of DNA 3.Recombinant DNA is inserted into bacteria cells 4.Bacteria cells reproduce, each containing the desired gene Cloning Procedure

What is cloning used for? Gene therapy Pharmaceutical drug production Increasing agricultural productivity Cloning

Patient lacking enzyme for normal white blood cell function Copy of normal enzyme gene inserted into a sample of patient’s white blood cells White blood cells containing normal gene returned to patient’s body Functioning white blood cells reproduce inside patient’s body Gene therapy is still under extensive research Gene Therapy

Human insulin produced by bacterial “factories” Human insulin-producing gene inserted into plasmids Plasmids inserted into bacteria cells Bacteria cells begin producing human insulin Pharmaceutical Drug Production

Bacteria used to produce growth hormone of cows – Increases milk production Increase plant resistance to disease Increasing Agricultural Productivity

Gene mapping – technique used to determine the specific location of a gene on a chromosome DNA probe – segment of DNA with a specific sequence Labeled with a radioactive or fluorescent tag Gene Mapping

Gene Mapping Procedure: 1.DNA probe created to match sequence of desired gene 2.Organism’s DNA is unwound 3.DNA probe base-pairs with complementary sequence in organism’s DNA 4.Radioactive or fluorescent tag identifies where probe is attached to chromosome Gene Mapping

What is gene mapping used for? Identifying the location of a gene allows scientists to manipulate it Genetic screening – Prenatal diagnosis of genetic diseases Examples: cystic fibrosis and Huntington’s disease – Presence of disease genes in adults Example: breast cancer gene Gene Mapping

Human genome project – effort to map the entire human genome Project Goals: – Identify all of the 20, ,000 genes in human DNA – Determine the sequences of the 3 million base pairs that make up human DNA Project Results: – Completed in 2003 – Human genetic information stored in databases – Improvements in tools for human genetic analysis Human Genome Project

Learning Objectives Describe common DNA technology techniques Identify how each technique is used to study or manipulate the genomes of organisms DNA Technology