1 / 16

GENETIC ENGINEERING 2

GENETIC ENGINEERING 2. Gel Electrophoresis, PCR and DNA FINGERPRINTING. Polymerase Chain Reaction. Section 13.2 Summary – pages 341 - 348. This is a method used to replicate DNA outside a living organism . Steps in PCR. 1. H eat is used to separate DNA strands from each other.

aram
Download Presentation

GENETIC ENGINEERING 2

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. GENETIC ENGINEERING 2 Gel Electrophoresis, PCR and DNA FINGERPRINTING

  2. Polymerase Chain Reaction Section 13.2 Summary – pages 341 - 348 This is a method used to replicate DNA outside a living organism. Steps in PCR 1. Heat is used to separate DNA strands from each other. 2. An enzyme (taq polymerase) isolated from a heat-loving bacterium is used to replicate the DNA when the appropriate nucleotides are added in a PCR machine( called a thermocycler.) 3. The machine repeatedly replicates the DNA, making millions of copies in less than a day.

  3. DNA Sequencing Section 13.2 Summary – pages 341 - 348 • Millions of copies of a double-stranded DNA fragment are cloned using PCR. Then, the strands are separated from each other. • The single-stranded fragments are placed in four different test tubes, one for each DNA base (A,C, G,T). • One nucleotide in each tube is tagged with a different fluorescent color. • The reactions produce complementary strands of varying lengths.

  4. Sequencing DNA contd. Section 13.2 Summary – pages 341 - 348 • These strands are separated according to size by gel, producing a pattern of fluorescent bands in the gel. • The bands are visualized using a laser scanner or UV light. • One method used for sequencing DNA is Gel Electrophoresis

  5. Gel Electrophoresis Section 13.2 Summary – pages 341 - 348 • One or several restriction enzymes are added to a sample of DNA. The enzymes cut the DNA into fragments. • Gel is molded so that small wells form at one end. Small amounts of the fragmented DNA are placed into these wells. DNA fragments

  6. Section 13.2 Summary – pages 341 - 348 An electric field Power source • The gel is placed in a solution and an electric field is applied making one end of the gel positive and the other end negative. Negative end Positive end

  7. The negatively charged DNA fragments travel toward the positive end. • The smaller the fragment, the faster it moves through the gel. • The smallest fragments move the farthest from the well. Section 13.2 Summary – pages 341 - 348 The fragments move Shorter fragments Longer fragments

  8. Mapping and Sequencing the Human Genome In 1990, scientists in the United States organized the Human Genome Project (HGP). Its purpose was to completely map and sequence the human genome.(approximately 35 000-40 000 genes on the 46 human chromosomes). Section 13.3 Summary – pages 349 - 353

  9. Linkage maps Section 13.3 Summary – pages 349 - 353 • The genetic map that shows the relative locations of genes on a chromosome is called a linkage map. Studying linkage data from human pedigrees was initially used to assign genes to a particular human chromosome. Problems with it included; a few offspring; human generation time is so long, mapping by linkage data is extremely inefficient

  10. New methods of mapping genes Section 13.3 Summary – pages 349 - 353 • Genetic marker: A segment of DNA with an identifiable physical location on a chromosome and whose inheritance can be followed. • A marker can be a gene, or it can be some section of DNA with no known function.

  11. Section 13.3 Summary – pages 349 - 353 Genetic Markers contd. • Because DNA segments that are near each other on a chromosome tend to be inherited together, markers are often used as indirect ways of tracking the inheritance pattern of a gene that has not yet been identified, but whose approximate location is known.

  12. Applications of the Human Genome Project Section 13.3 Summary – pages 349 - 353 • Diagnosis of genetic disorders (Prenatal or After birth) • How? By comparing the DNA of people with or without the disorder. • Gene therapy: The insertion of normal genes into human cells to correct genetic disorders. • Trials that treat SCID (severe combined immunodeficiency syndrome) have been the most successful • Testing on cystic fibrosis, sickle-cell anemia, hemophilia in progress.

  13. Section 13.3 Summary – pages 349 - 353 Steps involved in Gene therapy Cell culture flask Add virus with functioning SCID gene Bone marrow cells Gene Bone marrow cell with integrated gene Hip Bone

  14. DNA fingerprinting Section 13.3 Summary – pages 349 - 353 • DNA fingerprinting can be used to convict or acquit individuals of criminal offenses because every person is genetically unique. • (genetic fingerprints not fingers!!!) • DNA fingerprinting works because no two individuals (except identical twins) have the same DNA sequences, and because all cells (except gametes) of an individual have the same DNA.

  15. Section 13.3 Summary – pages 349 - 353 DNA fingerprinting • In a forensic application of DNA fingerprinting, a small DNA sample is obtained from a suspect and from blood, hair, skin, or semen found at the crime scene. • The DNA, which includes the unique non-coding segments, is cut into fragments with restriction enzymes.

  16. DNA fingerprinting Section 13.3 Summary – pages 349 - 353 • The fragments are separated by gel electrophoresis, then further analyzed. If the samples match, the suspect most likely is guilty.

More Related