Applications of genetics

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  • CLONING
    • APPLICATIONS OF GENETICS
      • GENE THERAPY
        • The Human Genome Project
          • determined the order of bases in the human genome.
          • identified some genes
          • addressed ethical and legal problems.
          • improved analytical tools.
          • applications of THGP
            • comparing patents and identifying mutated genes to healthy genes using gene probes.
            • carrier screening
            • pre-implanation screening
            • forensic testing
          • evaluation of the THGP
            • Practical uses
            • reduce illness and suffereing
            • pre-symptomatic testing can lead to discrimination and stigma.
              • symptoms can sometimes appear earlier.
              • risk of false positive- so people will be anxious without need.
            • family testing- your own test may have implications for your family.
        • WHAT IS GENE THERAPY?
          • treats a genetic disease by replacing copies of a fault gene with copies of a new healthy sequence.
          • somatic cell therapy
            • replaces genes in affected tissues
              • therapeutic not inherited
            • both use a vector such as plasmid dna, or virus.
              • germ line therapy
                • change of gene is inserted into germ-line cells.
                  • inherited change.
          • germ line therapy
            • change of gene is inserted into germ-line cells.
              • inherited change.
        • CYSTIC FIBROSIS
          • CAUSE
            • Recessive allele of the CFTR gene
              • CFTR gene makes protein which transports chloride ions out the cell. This function is stopped in cystic fibrosis.
                • causing salts and water to remain in cell.
                  • so mucus is thick, sticky and viscous.
              • changing one amino acid.
          • symptoms
            • food digestion as mucus blocks the pancreatic duct so enzymes cannot reach the duodenum.
            • clogged airways resulting in infections and breathing problems.
          • daily treatment
            • physio therapeutic chest massage
            • large food intake and appetite!
          • gene therapy for cystic fibrosis
            • LIPOSOMES
              • Healthy gene is inserted into a liposome
                • which are inhaled via a aerosol
                  • liposomes are absorbed into epithelial cells of lungs
                    • healthy gene is expressed via protein synthesus
            • VIRUS
              • virus is rendered harmless by removing harmful genes.
                • cultured in epithelial cells with palsmids holding the healthy CFTR gene.
                  • virus takes up normal gene.
                    • vrius is isolated and introduced to pateint via inhaler
                      • virus injects CFTR gene into epithelial cells of the lungs.
            • limited success as the effect is shortlived, and there could be an immune response.
              • however, does improve quality of life, so useful.
        • Genetic screening
          • tests a child for a faulty gene
          • blood test
          • amniocentesis
          • chlorionic villus sampling
        • Genetic counselling
          • family members seeking advice concerning the chances of having an effected child.
          • helps people make informed decisions about life and offsping.
        • Advantages of gene therapy
          • improves quality fo life
          • informed decision about pregnancy
          • reduces harmful alleles in population
          • less cost for NHS
        • Disadvanatges of gene therapy
          • Privacy invasion
          • increase number of aborions
          • insurance companies may increase rates for those with genetic differences.
          • fears of eugenics
            • germline- unforeseen consequences for future generations.
      • GENETIC ENGINEERING
        • identifying gene
          • uses probes:
            • containing complementary sequence for the beginning of the gene,
        • isolating gene
          • resitrcition endonuclease
            • vector is plasmid.
              • it carries recombinant DNA.
              • restriction enzymes cut the foreign DNA at particular sites .
                • forming sticky ends
                • complentary sticky ends are produced in the plasmid DNA
                  • DNA ligae anneals the two ends tOgether.
                    • forming sticky ends
                    • Plasmids are taken up by bacteria, and then the gene is expressed via protein synthesis.
                      • uptake of plamsids by bacteria is very small.
                        • DNA polymerase converts it to a double strand, to incorporate into a plasmid.
                        • antibiotic resistant sequences are used to identify bacteria which have recombinant DNA/
          • reverse transcripatse
            • an enzyme that makes DNA from mRNA.
            • mRNA is extracted from suitable cells.
              • reverse transcirptase makes a single DNA strand of the desired gene
                • DNA polymerase converts it to a double strand, to incorporate into a plasmid.
              • this is good as it misses out introns.
        • advantages of engineering
          • a complex protein can be made quickly
          • dangerous practice of protein removal from corpses or animals can be eliminated.
          • health benefits for those with diseases.
        • disadvantages of engineering
          • complicated and expensive
          • huge genome= difficulty in finding gene
          • one protein may require many genes.
            • or even genes to synthesis enzymes to make the proetin!
          • not all genes can be expressed by bacteria.
          • HAZRADS
            • Bacteria exchange material readily, so a harmful gene could be produced on a huge scale and affect thousands receiving treatment.
            • deliberate use of antibiotic restant genes could result in resistant bacteria on a large scale.
      • GENETIC FINGERPRINTING
        • an individuals genetic fingerprint or DNA profile is completely unique.
          • introns don't code for polypeptides, but vary between individuals as they are repeated.
        • DNA is extracted and cut into fragments by restriction enzymes.
          • fragments are separated by electrophoresis.
            • DNA is negatively charged.
            • small fragments move furthest to the positive terminal.
            • fragments are transferred to a nylon membrane and exposed to probes.
              • dna fragments not attached to a probe are washed off.
                • bands left are original for individual.
                • nylon membrabe is exposed to xray film, which is exposed by radioactive probes.
                  • giving a autoradiograph.
          • PCR and gene amplification
            • needs DNA polymerase, nucleotides and primers
            • 95°C-
              • 55°C
                • 70°C
                  • dna polymerase works fast to make double helix.
                • allows primers to join to complementary sequences.
              • separates DNA strands
        • USES
          • Paternity testing
          • foensics
        • issues with privacy
          • mass amount of information needs to be stored appropriately
          • however- many genomes are being stored and recorded, so ensure unbiased record of human genome..
      • GENETIC MODIFICATION
        • GM: HOW
          • uses a species of bacetria which attacks plants to cause tumours. bad gene is removed and replaced with useful ones.
        • GM: Examples
          • herbicide resistant soya beans
            • lead to socio-economic and environmental problems.
          • FlavrSavr tomatoes. Has complementary gene to the enzyme that breaks down pectin. mRNA strands join, so enzyme isnt made.
        • benefits of GM
          • superiro keeping qualities
          • increased yield
            • plants that grow better when less water/nitrates
          • resistant plants results in les use of pesticides.
        • problems with gm
          • genetyiclly engineered pollen could reach wild plants.
            • reducing variation between species.
              • reduction in biodiversity.
          • new protein may be harmful to eat.
            • antibiotic resistant genes transferred to bacteria in gut.
          • farmer shave less choice of crops, so their crops are high susceptible to disease.
          • lead to socio-economic and environmental problems.
    • PLANTS
      • micropropagation
        • remove meristem part of plant with sterile equipment.
          • explants alllowed to grow in sterile medium into callus
            • callus is cut up and allowed to specialise into plantlets
              • plantlets are planted into sterile soil
            • via mitosis
      • ADVANTAGES for plants
        • speed of production as avoid pollination and fertilization process
        • large quantities
          • of uniform crop
        • identical, germ line with a advantageous genes- insect resistanc
      • DISADVANTAGES
        • easily infected crops if the conditions are not sterile.
        • uniformity makes crop very vulnerable to widespread disease
        • high mutation rates due to genetic unstability.
    • ANIMALS
      • embryonic
        • nucleus removed from a donor egg cell (enucleation)
        • nucelus taken from a donor somatic cell
          • somatic nucleus put into empty egg cell.
            • nucleus removed from a donor egg cell (enucleation)
            • egg cell treated will chemicals or electric shock to start mitosos
              • cell dveelops into embryo and is implanted into surrogate mother.
      • advantages for animal cloning
        • large quantities
        • indentical geneticall advanatgeous organisms.
      • disadvantages for animal cloning
        • expensive and unrelaible
        • inadvertent selection of disadvantageous genes e.g. ageing.
    • TISSUE CULTURE
      • used to:
        • create clones a single identical genetic line
          • with desirable characteristics
        • e.g. cancer cells for medical research
      • applications
        • STEM  CELLS
          • undiffrentiate cells which can specialised into any type of cell.
          • used to make blood vessels, cartilage skin grafts
            • patients do not rject the implants as they their own DNA.
          • ethics for stem cells
            • surplus embryos from IVF are destroyed after stem cells are removed- some people consider this murder?
            • benefits may outweigh concerns- could be used to treat alzheimers, parkinsons, and heart disease.
            • stem cells can be obtained from bone marrow but less diverse applications and more invasive.

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