Frontiers of Biotechnology

1. Frontiers of Biotechnology Chapter 9

2. What is Biotechnology? • A group of technologies that work with living cells and molecules to enhance crops, fuels, and medical treatments to help improve our lives. • Example: genetic engineering

3. Genetic research requires that scientists manipulate DNA • DNA is a small molecule, scientists have developed specific techniques and tools to work with DNA • Biotechnology relies on cutting DNA at specific places

4. Restriction enzymes cut DNA • Different segments of a chromosome are genes. • Chromosomes need to be “cut” into pieces to study individual genes. • It is the job of restriction enzymes to cut up DNA

5. Restriction Enzymes • When viruses attack bacteria the bacteria produce restriction enzymes that cut up the DNA of viruses • These restriction enzymes can be used to cut DNA in other organisms

6. Restriction enzymes cut DNA • Restriction enzymes act as “molecular scissors” to cut DNA and manipulate genes • DNA is cut at a specific nucleotide sequence called a restriction site

7. Restriction enzymes cut DNA • Different restriction enzymes cut DNA in different ways. • Each enzyme has a different restriction site

8. Restriction enzymes cut DNA • Restriction enzymes recognize nucleotide sequences that are 4 – 8 base pairs long then they cut across the strands • some cut straight across and leave “blunt ends” • some make staggered cuts and leave “sticky ends”

9. Restriction Mapping Occurs After Genes Are Cut • Genes must be separated after being cut by restriction enzymes • Gel electrophoresis is used to separate DNA fragments by size. • DNA sample is loaded into a gel, a positive electrode is at one end of the gel a negative electrode is at the other end • Electrical current pulls DNA fragments through a gel

10. Restriction Mapping • Smaller fragments move faster and travel farther than larger fragments. • Fragments of different sizes appear as bands on the gel.

11. Restriction Mapping • The bands on a gel indicate only the length not the DNA sequence. • A restriction map shows the lengths of DNA fragments between restriction sites. • useful in genetic engineering • used to study mutations, how? • A mutation may add or delete bases between restriction sites changing the length of DNA fragment • A mutation may change the restriction site and the DNA would not be cut in the same places

12. target sequence of DNA How do scientists get enough DNA to work on? • Scientists copy the same segment of DNA multiple times using Polymerase chain reaction (PCR) • PCR makes many copies of a specific DNA sequence in a few hours.

13. DNA strands primer1 polymerase primer 2 nucleotides PCR PCR uses four materials. • DNA to be copied • DNA polymerase • A, T, C, and G nucleotides • two primers

14. DNA strands primer1 polymerase primer 2 nucleotides PCR is a three step process • Heat is used to separate double-stranded DNA molecules • Primers bind to each DNA strand on opposite ends of the segment to be copied • DNA polymerase binds nucleotides together to form new strands of DNA

15. PCR • Each PCR cycle doubles the number of DNA molecules.

16. DNA Fingerprinting • A DNA fingerprint is a representation of parts of an individual’s DNA that can by used to identify a person at the molecular level. • A DNA fingerprint is a type of restriction map

17. DNA Fingerprinting • A DNA fingerprint is based on noncoding regions of DNA • noncoding regions have repeating DNA sequences • number of repeats differs between people • banding pattern on a gel is a DNA fingerprint

18. DNA Fingerprinting is used for Identification (mother) (child 1) (child 2) (father) • DNA fingerprinting depends on the probability of a match • Many people have the same number of repeats in a certain region of DNA. • The probability that two people share identicalnumbers of repeats in several locations is very small.

19. DNA Fingerprinting and Probability 1 1 1 1 500 90 120 5,400,000 x x = = 1 chance in 5.4 million people • Individual probabilities are multiplied to find the overall probability of two DNA fingerprints randomly matching. • Suppose there was a 1 in 500 hundred chance of matching a DNA fingerprint at location A on a chromosome, a 1 in 90 for location B and a 1 in 120 for location C then the probability would be: • Several regions of DNA are used to make DNA fingerprints.

20. Uses of DNA Fingerprinting • DNA fingerprinting is used in several ways. • evidence in criminal cases • paternity tests • immigration requests • studying biodiversity • tracking genetically modified crops

21. Genetic Engineering • Entire organisms can be cloned. • A clone is a genetically identical copy of a gene or of an organism • Cloning occurs in nature • bacteria (binary fission) • some plants (from roots) • some simple animals (budding, regeneration) • Identical twins are clones

22. Genetic Engineering • Mammals can be cloned through a process called nuclear transfer. • nucleus is removed from an egg cell • nucleus of a cell from the animal to be cloned is implanted in the egg

23. Genetic Engineering • Cloning has potential benefits. • organs for transplant into humans • save endangered species • Cloning raises concerns. • low success rate • clones “imperfect” and less healthy than original animal • decreased biodiversity

24. Genetic Engineering: New genes can be added to an organism’s DNA. (bacterial DNA) • Genetic engineering involves changing an organism’s DNA to give it new traits. • Genetic engineering is based on the use of recombinant DNA. • Recombinant DNA contains genes from more than one organism.

25. Genetic Engineering: New genes can be added to an organism’s DNA. • Bacterial plasmids are used to make recombinant DNA. • plasmids are loops of DNA in bacteria • restriction enzymes cut plasmid and foreign DNA • foreign gene inserted into plasmid • New plasmid is put into bacteria to make copies of the gene and what it expresses

26. Genetic Engineering: New genes can be added to an organism’s DNA. • A transgenic organism has one or more genes from another organism inserted into its genome. • The gene for human insulin can be put into plasmids • The plasmid is then put in a bacteria which then makes insulin • The insulin is collected and used to treat diabetes

27. Genetic Engineering: New genes can be added to an organism’s DNA. • Transgenic plants are common in agriculture. • transgenic bacteriainfect a plant • plant expressesforeign gene • many crops are nowgenetically modified(GM)

28. Genetic Engineering: Transgenic animals are used to study diseases and gene functions. • Transgenic animals are more difficult to produce than plants • Transgenic mice used as models of human development and disease • The first such animal was the oncomouse because it always develops cancer (the gene to control cell growth was mutated) • Some mice have their genes turned “off”: geneknockout miceand are used to study gene function

29. Genetic Engineering: Genetically modified Food • Scientists have concerns about some uses of genetic engineering. • possible long-term health effects of eating GM foods • possible effects of GM plants on ecosystems and biodiversity

30. Genomics involves the study of genes, gene functions, and entire genomes. • Genomics is the study of genomes. • can include the sequencing of the genome • comparisons of genomes within and across species • helps find the genes that cause disease and how medicines work • examine closely related species

31. Genomics involves the study of genes, gene functions, and entire genomes. • All studies of genomics begin with gene sequencing, determining the order of DNA nucleotides in genes or in genomes. • The genomes of several different organisms have been sequenced.

32. Genomics involves the study of genes, gene functions, and entire genomes. • The Human Genome Project has sequenced all of the DNA base pairs of human chromosomes. • analyzed DNA from a few people • still working to identify and map human genes

33. Genomics and Bioinformatics. • Technology allows the study and comparison of both genes and proteins. • Bioinformatics is the use of computer databases to organize and analyze biological data. • DNA microarrays are used to study the expression of many genes at once. • Proteomics is the study and comparison of proteins.

34. Genetics provides a basis for new medical treatments. DMD N • Genetic screening can detect genetic disorders. • Genetic screening involves the testing of DNA. • determines risk of havingor passing on a geneticdisorder • used to detect specificgenes or proteins • can detect some genesrelated to an increasedrisk of cancer • can detect some genesknown to cause geneticdisorders

35. Genetics provides a basis for new medical treatments. • Gene therapy is the replacement of faulty or missing genes or adds new genes, to treat a disease • Several experimental techniques are used for gene therapy. • genetically engineered viruses used to “infect” a patient’s cells • insert gene to stimulate immune system to attack cancer cells • insert “suicide” genes into cancer cells that activate a drug

36. Genetics provides a basis for new medical treatments. • Gene therapy has many technical challenges • inserting gene into correct cells • controlling gene expression • determining effect on other genes