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
Produce human growth hormones
Genes for pest resistance
Basic gene research Gene used to alter
bacteria to clean up for oil spill
Protein dissolves blood clots in heart attack
Basic protein research
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
- 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 supplye.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
Application of Genetic Engineering
Dolly News Clip
CloneA 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