chapter 13 recombinant dna and genetic engineering n.
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Chapter 13 – Recombinant DNA and Genetic Engineering. College Prep Biology Mr. Martino. Introduction. Gene Therapy: transfer of one or more modified genes into an individual’s cells Correct genetic defect Boost immune system

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Chapter 13 – Recombinant DNA and Genetic Engineering

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  • Gene Therapy: transfer of one or more modified genes into an individual’s cells
    • Correct genetic defect
    • Boost immune system
  • Recombinant DNA Technology: science of cutting and recombining DNA from different species
    • Genes are then placed into bacterial, yeast or mammalian cells and replicated
  • Genetic Engineering: genes are isolated, modified, and inserted back into a cell
    • also called biotechnology
15 1 making recombinant dna
15.1 Making Recombinant DNA
  • Restriction enzyme: enzyme that chops up DNA at a specific sequence
    • Bacterial
    • Viral defense mechanism
    • May cut a DNA strand a few times
    • Helpful in studying DNA
    • Produces “sticky ends” which may pair with other DNA
  • Genome: all the DNA in a haploid number of chromosomes for each species
Plasmids: small circle of DNA
    • In bacterial cells
    • Insert foreign DNA (gene) into and put back in bacteria – reproduces naturally making a DNA clone
    • Cloning vector: plasmid used to accept foreign DNA and replicate it
  • Reverse transcriptase: enzyme from RNA viruses that perform transcription in reverse (RNA to DNA)
    • cDNA: (copied DNA) mature mRNA transcript that has already been spliced
      • Bacteria cannot remove introns and splice exons
      • Reverse transcriptase makes DNA from mRNA to insert into plasmid
15 2 pcr polymerase chain reaction
15.2 PCR – Polymerase Chain Reaction
  • PCR: a fast method of amplifying (making lots of copies) DNA
    • DNA isolated, mixed with DNA polymerase, nucleotides, and some other good stuff
      • Produces 2 daughters
      • Daughters replicate, etc.
      • 1 DNA molecule generates 100 billion in a few hours
    • Used in evolution research, analyze DNA from fossils, analyze embryos, court cases
15 3 dna fingerprints
15.3 DNA Fingerprints
  • No two people have exactly identical DNA
    • Except identical twins
  • DNA Fingerprint: unique set of DNA fragments
    • Used to determine paternity, solve crimes, etc.
    • 99.9% all human DNA is identical
    • Focus on highly variable areas of tandem repeats
      • Mutations occur within families and are more common in these areas
Gel electrophoresis: uses an electric current to force DNA fragments through a gel
    • DNA is negative
    • Size of fragment determines how far it migrates
      • The fewer tandem repeats the farther it travels
      • Differences in homologous DNA sequences resulting in fragments of different lengths are restriction fragment length polymorphisms (RFLP’s)
15 4 dna sequencing
15.4 DNA Sequencing
  • 1995 – entire DNA sequence for a bacterium was determined
  • 4/25/03 – Human genome completed
  • Several bacteria, yeast, Drosophila,C. elegans - worm, Arabidopsis - weed, Mickey…a mouse, just completed 3/31/04 – a rat)
  • Used a sequencing machine
15 5 isolating genes
15.5 Isolating Genes
  • Genomic Library: set of DNA fragments from an organism’s genome
  • Complementary RNA sequence can be synthesized with a radioactive isotope tag called a probe
    • Used to find a specific gene
    • Tags the gene whenever encountered
    • Gene may then be isolated
15 6 using the technology
15.6 Using the Technology
  • True human insulin is now manufactured
  • Also somatotropin (growth hormone), blood-clotting factors, hemoglobin, interferons (cancer research), and various other drugs and vaccines
  • Bacteria for oil spill clean up and other environmental pollution
15 7 designer plants
15.7 Designer Plants
  • Genetically engineered plants have been developed for pharmaceuticals, herbicide, pest, and disease resistance, larger and tastier plants, fruits, and vegetables with greater yields
    • Corn, cotton, potato, soy bean, etc
15 8 gene transfers in animals
15.8 Gene Transfers in Animals
  • Cloning holds promises for future
    • Clone organs and tissues
    • Possibly modify animals to be more disease resistant and produce greater quantities of products
    • Not currently occurring in farm animals
1997 – the first animal was cloned – Dolly a lamb
    • 1. Remove nucleus from cell
    • 2. Transfer nuclei from desired cells into unfertilized eggs
    • 3. Implant the “zygote” into surrogate mother
    • Since Dolly – we have cloned mice, rats, cows, cats, mules, horses, and Rhesus monkeys along with a couple of endangered animals
human genome
Human Genome
  • HGP – an int’l effort to map and sequence all human genes
    • 15 countries started 11/1/90 and finished 4/25/03 (50 years after Watson & Crick paper published)
    • 1. Genome – only 30,000 genes so it took less time
      • Includes mapping & sequencing of other species for comparison
    • 2. RNA transcription – more difficult since 30,000 genes code for 80,000 proteins due to alternative splicing
    • 3. Proteome – quest for every human protein
15 9 who gets enhanced
15.9 Who Gets Enhanced?
  • HGP already has an ethics committee due to insistence of James Watson
    • HGP needs to be used to help people and must be regulated by laws
    • Must prevent invasion of privacy and discrimination by insurance companies, employers,etc.
    • Must prevent Eugenics: purging of “undesirable” traits from human population (Hitler)
    • Science provides society with knowledge and opportunities – society requires rules and constraints to prevent abuse