Question

1.) Describe the four stages of genetic engineering: cleave DNA & insert into cloning vector -producing recombinant DNA, insert recombinant vector into bacterial cells -cloning, amplification of recombinant vector, screening for recombinant DNA.

2.) What and how are antibiotic resistance and the lacZx gene used in screening?

3.) What is Agrobacterium tumefaciens? What normally occurs upon Agrobacterium tumafaciencs infection in plants? How is it used to genetically engineer plants (stably insert foreign genes into plants)?

Answer 1

Genetic Engineering is the transfer of DNA from one organism to another using biotechnology. The organism receiving the DNA is said to be genetically modified (GM).

Organisms are genetically modified in order to give them a combination of genes (genotype) that will result in them having desirable physical characteristics (phenotype). Often the desirable characteristic is simply the ability to produce large quantities of a useful protein.

Bacterial cells can be genetically modified so that they have the gene for producing human insulin. As these modified bacteria grow, they produce human insulin. This protein can be purified and supplied to diabetics.

Main stages of genetic Engineering

• DNA cleavage (stage 1) - restriction endonuclease cleaves DNA into fragments.
• recombinant DNA production (stage 2) - DNA fragments inserted into vectors.
• cloning (stage 3) - more recombinant DNA created.
• screening (stage 4) - most challenging part of any genetics experiment.

  The stages of this method of genetic engineering are:

• The location of the section of DNA containing the gene for making the human protein insulin must be identified (it is on human chromosome number 7).
• A specific enzyme is used to extract the required gene from the human chromosome.
• Plasmids are then removed from bacterial cells.
• The DNA of the plasmids is cut open with a specific enzyme.
• The human insulin gene is inserted into each plasmid.
• The plasmid acts as a vector - it is used to transfer DNA from one organism to another.
• Bacterial cells are made to take up the genetically modified plasmids.
• Bacterial cells that successfully take up plasmids are described as being transformed. They can also be called genetically modified organisms. The bacteria are host cells for the plasmids.
• Each bacterial cell will produce a tiny mass of insulin.
• By culturing the genetically modified bacteria large quantities of insulin protein can be produced and extracted.