Ap Bio Ch 13 Power Point


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  • Ap Bio Ch 13 Power Point

    1. 1. Biotechnology
    2. 2. Traditional Applications <ul><li>Biotechnology is applied biology </li></ul><ul><ul><li>Modern focus on genetic engineering, recombinant DNA technology, and analysis of biomolecules </li></ul></ul>
    3. 3. Traditional Applications <ul><li>Traditional (historical) applications of biotechnology date back to over 10,000 years ago </li></ul><ul><ul><li>Use of yeast to produce beer and wine in Egypt and Near East </li></ul></ul><ul><ul><li>Selective breeding of plants </li></ul></ul><ul><ul><li>Selective breeding of animals </li></ul></ul>
    4. 4. Genetic Engineering <ul><li>Genetic engineering refers to the modification of genetic material to achieve specific goals </li></ul><ul><ul><li>Learn more about cellular processes, including inheritance and gene expression </li></ul></ul><ul><ul><li>Provide better understanding and treatment of diseases, particularly genetic disorders </li></ul></ul><ul><ul><li>Generate economic and social benefits through production of valuable biomolecules and improved plants and animals for agriculture </li></ul></ul>
    5. 5. Recombinant DNA <ul><li>Genetic engineering utilizes recombinant DNA technology </li></ul><ul><ul><li>Splicing together of genes or portions of genes from different organisms </li></ul></ul><ul><li>Recombinant DNA can be transferred to plants and animals </li></ul><ul><ul><li>Modified animals are called transgenic or genetically modified organisms (GMOs) </li></ul></ul><ul><ul><li>Most modern biotechnology includes manipulation of DNA </li></ul></ul>
    6. 6. Recombination in Nature <ul><li>Many natural processes recombine DNA: </li></ul><ul><li>Due to crossing over during meiosis, each chromosome in a gamete contains a mixture of alleles from the two parental chromosomes </li></ul><ul><ul><li>Thus, eggs and sperm contain recombinant DNA </li></ul></ul>
    7. 7. Transformation <ul><li>Bacteria can naturally take up DNA from the environment ( transformation ) and integrate the new genes into the genome ( recombination ) </li></ul>
    8. 8. Recombination in Bacteria 1 µ m (a) (b) (c) Bacterium Chromosome Plasmid Plasmid replicates in cytoplasm DNA fragment incorporated into chromosome Plasmid transferred to new host DNA fragments transferred to new host
    9. 9. Transformation <ul><li>Small circular DNA molecules ( plasmids ) carry supplementary genes </li></ul><ul><ul><li>Plasmid genes may allow bacteria to grow in novel environments </li></ul></ul><ul><ul><li>Plasmid genes may enhance virulence of bacteria in establishing an infection </li></ul></ul><ul><ul><li>Plasmid genes may confer resistance to antimicrobial drugs </li></ul></ul>
    10. 10. Viral Transfer of DNA <ul><li>Viral life cycle </li></ul><ul><ul><li>Viral particle invades host cell </li></ul></ul><ul><ul><li>Viral DNA is replicated </li></ul></ul><ul><ul><li>Viral protein molecules are synthesized </li></ul></ul><ul><ul><li>Offspring viruses are assembled and break out of the host cell </li></ul></ul>
    11. 11. Viral Transfer of DNA <ul><li>Viral transfer of DNA </li></ul><ul><ul><li>Viruses may package some genes from host cell into viral particles during assembly </li></ul></ul><ul><ul><li>Infection of new host cell injects genes from previous host, allowing for recombination </li></ul></ul>
    12. 12. Viruses May Transfer Genes
    13. 13. Biotechnology and Forensics <ul><li>Forensics is the science of criminal and victim identification </li></ul><ul><li>DNA technology has allowed forensic science to identify victims and criminals from trace biological samples </li></ul><ul><ul><li>Genetic sequences of any human individual are unique </li></ul></ul><ul><ul><li>DNA analysis reveals patterns that identify people with a high degree of accuracy </li></ul></ul>
    14. 14. Polymerase Chain Reaction <ul><li>Forensic technicians typically have very little DNA with which to perform analyses </li></ul><ul><li>Polymerase Chain Reaction (PCR) produces virtually unlimited copies of a very small DNA sample </li></ul>
    15. 15. Polymerase Chain Reaction <ul><li>PCR requires small pieces of DNA (called primers ) that are complementary to the gene sequences targeted for copying </li></ul><ul><li>A PCR “run” is basically DNA replication in a tiny test tube </li></ul><ul><ul><li>Template DNA, primer, nucleotides, and DNA polymerase are all in the reaction mix </li></ul></ul>
    16. 16. Polymerase Chain Reaction <ul><li>Four steps of a PCR cycle </li></ul><ul><ul><li>Template strand separation </li></ul></ul><ul><ul><ul><li>The test tube is heated to 90-95 o C to cause the double stranded template DNA to separate into single strands… </li></ul></ul></ul><ul><ul><li>Binding of the primers </li></ul></ul><ul><ul><ul><li>The temperature is lowered to 50 o C to allow the primer DNA segments to bind to the targeted gene sequences through hydrogen bonding… </li></ul></ul></ul>
    17. 17. Polymerase Chain Reaction <ul><ul><li>New DNA synthesis at targeted sequences </li></ul></ul><ul><ul><ul><li>The temperature is raised to 70-72 o C where the heat-stable DNA polymerase synthesizes new DNA of the sequences targeted by the primers… </li></ul></ul></ul><ul><ul><li>Repetition of the cycle </li></ul></ul><ul><ul><ul><li>The cycle is repeated automatically (by a thermocycler machine) for 20-30 cycles, producing up to 1 billion copies of the original targeted DNA sequence </li></ul></ul></ul>
    18. 18. Polymerase Chain Reaction: (a) One PCR Cycle Original Double- helix DNA Separate DNA Strands 90 °C Primers & DNA polymerase bind 50 °C DNA Polymerase Primer DNA 72 °C DNA synthesized
    19. 19. Polymerase Chain Reaction: (b) Multiple PCR Cycles DNA fragment to be amplified 2 copies 4 copies 8 copies
    20. 20. Polymerase Chain Reaction <ul><li>Choice of primers determines which sequences are amplified (copied) </li></ul><ul><li>Forensic scientists focus on short tandem repeats (STRs) found within the human genome </li></ul>
    21. 21. Polymerase Chain Reaction <ul><li>STRs are repeated sequences of DNA within the chromosomes that do not code for proteins </li></ul><ul><li>STRs vary greatly between different human individuals </li></ul><ul><li>A match of 10 different STRs between suspect and crime scene DNA virtually proves the suspect was at the crime scene </li></ul>
    22. 23. Gel Electrophoresis <ul><li>Mixtures of DNA fragments can be separated on the basis of size </li></ul><ul><li>Gel electrophoresis is a technique used to spread out different-length DNA fragments in a mixture </li></ul>
    23. 24. Gel Electrophoresis <ul><li>Four steps of gel electrophoresis </li></ul><ul><ul><li>DNA mixtures are placed into wells at one end of a slab of agarose gel </li></ul></ul><ul><ul><li>An electric current introduced through the gel causes the negatively-charged DNA fragments to migrate towards the positive electrode </li></ul></ul>
    24. 25. Gel Electrophoresis <ul><li>Four steps of gel electrophoresis </li></ul><ul><ul><li>Short DNA fragments move more easily through the three-dimensional meshwork of fibers between the gel </li></ul></ul><ul><ul><ul><ul><li>Short DNA fragments migrate farther than long DNA fragments so the mixture is separated into bands of DNA of specific lengths </li></ul></ul></ul></ul><ul><ul><li>The invisible bands of DNA are made visible using stains or DNA probes </li></ul></ul>
    25. 28. RFLP: Gel Electrophoresis Direction of Migration Larger fragments move more slowly; smaller fragments move more rapidly
    26. 29. DNA Fingerprinting <ul><li>DNA from a crime scene sample can be amplified by PCR and run on a gel with suspect DNAs </li></ul><ul><li>Short tandem repeats (STRs) in the gel DNA can be identified by DNA probes </li></ul><ul><li>Distinctive pattern of STR numbers and lengths are fairly unique to a specific individual (forming a DNA fingerprint ) </li></ul><ul><li>DNA fingerprint from crime scene can be matched with DNA fingerprint of suspect </li></ul>
    27. 30. DNA Fingerprint in Forensics C   S R   C I   E M   N E   E 1 2 3 4 5 6 7 Suspects Suspects Q: Which suspect should be indicted? A: #3 is prime suspect
    28. 31. <ul><li>You can read the stuff on DNA probes and Biotech in Agriculture on your own… </li></ul>
    29. 32. Restriction Enzymes Cut DNA <ul><li>A DNA sequence (e.g. a gene) can be removed from a chromosome using special enzymes </li></ul><ul><li>Restriction enzymes are nucleases that cut DNA at specific nucleotide sequences </li></ul>
    30. 34. Restriction Enzymes Cut DNA <ul><li>Enzymes that create staggered cuts with “ sticky ends ” are the most useful in gene cloning </li></ul>
    31. 35. Splicing of DNA Fragments <ul><li>Sticky ends allow for splicing of a DNA fragment with another complementary fragment </li></ul><ul><ul><li>Bt gene can be cut out of the Bacillus chromosome with the same enzyme used to cut open the plasmid </li></ul></ul><ul><ul><li>Bt gene fragment ends can base-pair with sticky ends of the opened plasmid, adding gene to the plasmid circle </li></ul></ul>
    32. 36. Splicing of DNA Fragments <ul><li>DNA ligase enzyme used next to permanently bond gene into plasmid </li></ul>
    33. 43. Plasmids Are Used to Insert Genes <ul><li>The Ti plasmid from Agrobacterium tumefaciens is ideal for transferring genes into plant chromosomes </li></ul>
    34. 44. Plasmids Are Used to Insert Genes <ul><li>Agrobacterium infects plant cells and inserts its small Ti plasmid into a plant chromosome in the nucleus </li></ul><ul><ul><li>Pathogenic effects of certain tumor-causing Ti plasmid genes can be disabled </li></ul></ul><ul><ul><li>A gene inserted into a Ti plasmid is therefore carried into the plant cell chromosomes by a natural process </li></ul></ul>
    35. 46. The Human Genome Project <ul><li>Findings </li></ul><ul><ul><li>Human genome contains ~25,000 genes </li></ul></ul><ul><ul><li>New genes, including many disease-associated genes have been discovered </li></ul></ul><ul><ul><li>Has determined the nucleotide sequence of all the DNA in our entire set of genes, called the human genome </li></ul></ul><ul><ul><li>The genes comprise 2% of all the DNA </li></ul></ul>
    36. 47. The Human Genome Project <ul><li>Applications </li></ul><ul><ul><li>Improved diagnosis, treatment and cures of genetic disorders or predispositions </li></ul></ul><ul><ul><li>Comparison of our genome to those of other species will clarify the genetic differences that help to make us human </li></ul></ul>
    37. 48. DNA Probes <ul><li>Defective alleles can also be identified using DNA probes </li></ul><ul><li>DNA probing is especially useful where there are many different alleles at a single gene locus </li></ul><ul><ul><li>Cystic fibrosis is a disease caused by any of 32 alleles out of 1000 total possible alleles </li></ul></ul>
    38. 49. DNA Probes <ul><li>Arrays of single-stranded DNA complementary to each of the defective alleles can be bound to filter paper </li></ul><ul><li>A person’s DNA sample is cut up and separated into single-strands </li></ul><ul><li>The array is bathed in the DNA sample </li></ul><ul><li>Strands of DNA binding to complementary sequence on the paper indicate presence of a defective allele in person’s genome </li></ul>
    39. 51. DNA Probes <ul><li>An expanded version of this type of DNA analysis is known as a microarray </li></ul><ul><li>A microarray contains up to thousands of probes for a variety of disease-related alleles </li></ul><ul><li>Microarray analysis has the potential to comprehensively identify disease susceptibility </li></ul>
    40. 53. Scientific Objections to GMOs <ul><li>Safety issues from eating GMOs </li></ul><ul><ul><li>Could ingestion of Bt protein in insect-resistant plants be dangerous to humans? </li></ul></ul><ul><ul><li>Are transgenic fish producing extra growth hormone dangerous to eat? </li></ul></ul><ul><ul><li>Could GM crops cause allergic reactions? </li></ul></ul><ul><ul><ul><li>USDA now monitors GM foods for allergic potential </li></ul></ul></ul><ul><ul><li>Toxicology study of GM plants (2003) concluded that ingestion of current transgenic crops pose no significant health dangers </li></ul></ul>
    41. 54. Scientific Objections to GMOs <ul><li>Environmental hazards posed by GMOs </li></ul><ul><ul><li>Pollen from modified plants can carry GM genes to the wild plant population </li></ul></ul><ul><ul><ul><li>Could herbicide resistance genes be transferred to weed species, creating superweeds? </li></ul></ul></ul><ul><ul><li>Could GM fish reduce biodiversity in the wild population if they escape? </li></ul></ul><ul><ul><ul><li>Reduced diversity in wild fish makes them more susceptible to catastrophic disease outbreaks </li></ul></ul></ul>
    42. 55. Scientific Objections to GMOs <ul><li>Environmental hazards posed by GMOs </li></ul><ul><ul><li>US found to lack adequate system to monitor changes in ecosystem wrought by GMOs (National Academy of Science Study 2003) </li></ul></ul>
    43. 56. The Human Genome <ul><li>Should parents be given information about the genetic health of an unborn fetus? </li></ul><ul><li>Should parents be allowed to select the genomes of their offspring? </li></ul><ul><ul><li>Embryos from in vitro fertilization are currently tested before implantation </li></ul></ul><ul><ul><li>Many unused embryos are discarded </li></ul></ul><ul><li>Should parents be allowed to design or correct the genomes of their offspring? </li></ul>
    44. 57. Hope through Gene Therapy
    45. 58. Human Cloning: Permanent Genetic Correction? Parents with genetic disease Zygote with defective gene Embryo with defective gene Baby with genetic disorder Cell Culture Viral vector with therapeutic gene Treated Culture Genetically corrected cell from culture Enucleated egg cell Genetically corrected egg cell Genetically corrected embryo clone Healthy baby
    46. 59. The end