Chapter 9 Genetic engineering

Deliberate manipulation of genes in an organism. Done in a lab by scientists Therapeutic substances such as human insulin.

Insulin came from pancreas obtained from slaughtered animals Genetically engineered E.coli cells to make human insulin

Tools used in genetic engineering Restriction enzymes Bacteria – restriction enzymes To breakdown phage DNA Extract the restriction enzyme from bacteria and use it genetic engineering EcoRI, BamHI – recognize specific sequence Staggered cuts on DNA Ends of the fragment are single stranded

Sticky ends Cohesive ends ligase

Vectors – carry the gene of interest into a bacterial cell. Plasmids Small enough – they can enter into the cell Selection markers – antibiotic resistance genes. Help in selecting the cells that have the gene of interest.

Gene library Collection of genes from an organism Mouse gene library, yeast gene library Biotechnology company Yeast gene library DNA – fragment – restriction enzyme – fragments are inserted into plasmids – introduced into a bacterial cell Each bacterial cell having the recombinant cell is a clone Large # clones – a clone for each gene that exists in the yeast cell

Hexokinase Malate Dehydrogebase pheromone Helps the cells To come together And mate

cDNA Complementary DNA Eukaryotic genes – introns and exons Introns – noncoding regions Exons - coding regions cDNA – synthetic gene – has only exons c stands for complementary DNA

If we want to introduce eukaryotic gene into a prokaryotic cell, we should use cDNA If we place natural eukaryotic gene into a Bacterial cell, it cannot remove the introns. Functional protein will not be produced by the prokaryotic cell.

Applications of genetic engineering Hormones – insulin Growth hormone – somatotorpin Produced by genetically engineered E.coli cells. Treat stunted growth Pituitary gland removed during autopsy.

vaccine Hepatitis B vaccine Genetically engineered Saccharomyces cells Vaccine has only the protein part of the virus. Does not have the genetic material of the virus No chance of getting the disease due to vaccination

Genetic screening Carrier of genetic disorder Cystic fibrosis genetic disorder Mutation in a gene that codes for a membrane protein. Protein is not functional Produce thick mucus blocks airways and causes various health problems.

Person has the disease – symptoms Some people are carriers One cystic fibrosis gene (father) one normal gene (mother) – heterozygous for cystic fibrosis Two carriers – have a baby – the baby can have the disease Genetic screening is used – procedure known as southern blotting.

Gel electrophoresis hybridize Single stranded DNA complementary

Agriculture

Forensic medicine Each person has a unique set of introns. restriction enzyme fragment pattern of DNA

Polymerase Chain Reaction Amplify DNA Target DNA Nucleotides DNA polymerase