Genetic Engineering II Do Now: What was Griffith’s experiment? What was his conclusion?

Transformation Scientists now know the following about Griffith’s experiment: The heat-killed bacteria must have contained DNA fragments When he mixed those fragments with live bacteria, a few of them actually took up the DNA molecules Conclusion: bacteria can be transformed simply by placing them in a solution containing DNA molecules During transformation, a cell takes in DNA from outside the cell: This external DNA becomes a part of the cell’s DNA

Transforming Bacteria Bacteria can be transformed using recombinant DNA: a form of artificial DNA that is created by combining 2 or more sequences that would not normally occur together Most recombinant DNA involves a small, circular DNA called plasmid Combine the 2 DNA strands with ligase

Plasmid Plasmids are found naturally in some bacteria and have been very useful for DNA transfer: Small extra circles of DNA located in the cytoplasm of the bacterial cell Carry extra genes that bacteria can use Can be swapped between bacteria Can be picked up from the environment

How can plasmids help us? It is a way to get genes into bacteria easily: Insert new gene into plasmid Insert plasmid into bacteria = vector Let the bacteria make proteins for that new gene

Applications of recombinant DNA and transformation Copies of Gene Copies of Protein Genes for pest resistance Produce human growth hormones Basic protein research Basic gene research Gene used to alter bacteria to clean up for oil spill Protein dissolves blood clots in heart attack

Application of Genetic Engineering Transgenic Organisms: Organisms that contain genes from other organism Transgenic microorganisms: Because they reproduce rapidly and are easy to grow, transgenic bacteria now produce a host of important substances useful for health and industry e.g. the human forms of proteins such as insulin, growth hormone and clotting factor

Application of Genetic Engineering Transgenic animals: They have been used to study genes and to improve the food supply e.g. spider goat, glow fish Transgenic plants: They are now an important part of our food supply e.g. Many of these plants contain genes that produce a natural insecticide, others have genes that enable then to resist weed killing chemicals

Application of Genetic Engineering Cloning: A clone is a member of a population of genetically identical cells produced from a single cell Cloned bacteria and other microorganism are easy to grow, but this is not true for animals In 1997, Scottish scientist Ian Wilmut cloned a sheep named Dolly

Dolly News Clip

Clone A donor cell is taken from a sheep’s udder These 2 cells are fused The nucleus of the egg cell is removed An egg cell is taken from an adult female sheep The fused cell begins dividing normally The embryo is placed in the uterus of a foster mother