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NIS - BIOLOGY

NIS - BIOLOGY. Lecture 57 – Lecture 58 DNA Technology Ozgur Unal. What comes to your mind when you hear the term “Genetic Engineering”?. Genetic Engineering.

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NIS - BIOLOGY

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  1. NIS - BIOLOGY Lecture 57 – Lecture 58 DNA Technology OzgurUnal

  2. What comes to your mind when you hear the term “Genetic Engineering”? Genetic Engineering

  3. Genetic engineering is the technology that involves manipulating the DNA of one organism in order to insert exogenous DNA (DNA of another organism). • Example: Researchers have inserted a gene for a bioluminescent protein called green fluorescent protein (GFP) into various organisms. • GFP is naturally present in jellyfishes in the north Pacific Ocean • Some organisms have been genetically • engineered to synthesize GFP. • Figure 13.3  mosquito larvae Genetic Engineering

  4. Selective breeding is used to produce plants and animals with desired traits. • Similarly, genetic engineering can be used to increase or decrease the expression of specific genes in selected organisms. • Genetic engineering has many applications  human health, agriculture etc. • But how are these • engineering processes • achieved? Genetic Engineering

  5. An organism’s genome is the total DNA present in the nucleus of each cell. • Human genome contains around 25,000 thousand genes. • In order to study a specific gene, DNA tools can be used to manipulate DNA and to isolate genes from the rest of the genome. DNA Tools

  6. Restriction Enzymes: • Some types of bacteria contain powerful defenses against viruses. • These cells contain proteins called restriction enzymes that recognize and bind to specific DNA sequences and cleave the DNA within that sequence. • A restriction enzyme, also called • endonuclease, cuts the viral DNA into • fragments after it enters the bacteria. • There are many different types of • restriction enzymes. DNA Tools

  7. Restriction Enzymes: EcoRI • One restriction enzyme that is widely used by scientists is EcoRI. • EcoRI specifically cuts DNA containing • the sequence GAATTC. • EcoRI cuts this sequence such that it • produces complementary sticky ends. • Not all restriction enzymes create • sticky ends! • http://highered.mcgraw-hill.com/olc/dl/120078/bio37.swf DNA Tools

  8. Gel Electrophoresis: • An electric current is used to separate the DNA fragments according to the size of the fragments in a process called gel electrophoresis. • Check out Figure 13.5!! • When an electric current is applied, the DNA fragments move toward the positive end of the gel. • The smaller fragments move faster • than the larger ones. • Portions of the gel containing each • band can be removed for further • study. DNA Tools

  9. After DNA fragments have been separated by gel electrophoresis, fragments can be removed and combined with DNA fragments from another source  recombinant DNA • Large quantities of recombinant DNA are needed to study them • In order to transfer the recombinant DNA into a bacterial cell, scientists use a carrier (also called vector)  Plasmid or Virus • Plasmids are small, circular and double stranded DNA molecules that occure naturally in bacteria and yeast. Recombinant DNA Technology

  10. If a plasmid and a DNA • fragment obtained from • another genome have been • cleaved by the same • restriction enzyme, the ends • of each DNA fragment will be • complementary and can be • combined. • An enzyme normally used by • cells in DNA repair and • replication, called DNA ligase, • joins the two DNA fragments • chemically. • Check out Figure 13.6!! Recombinant DNA Technology

  11. Gene cloning is used to make large quantities of recombinant plasmid DNA. • Some bacterial cells take up the recombinant plasmid DNA into them through a process called transformation. • Bacteria can be transformed using electric pulsation or heat. • Large quantities of identical bacteria, each containing the inserted DNA molecules, can be produced through a process called cloning. • Check out Figure 13.7!! Gene Cloning

  12. The sequence of the DNA • nucleotides of most • organisms is unknown. • Knowing the sequence is • a valuable is information • to have. • Check out Figure 13.8 for • the steps in DNA • sequencing technique!! DNA Sequencing

  13. Once the sequence of a DNA fragment is known, a technique called the polymerase chain reaction, PCR, can be used to make millions of copies of a specific region of a DNA fragment. • PCR is extremely sensitive and can detect a single DNA molecule in a sample. • Follow the steps of PCR from the book and check out Figure 13.9!! • http://www.dnalc.org/resources/animations/pcr.html • http://www.maxanim.com/genetics/PCR/PCR.htm • Check out Table 13.1 for the differences in the DNA manipulation techniques we learned so far. Polymerase Chain Reaction

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