DNA technology

  • 1882, Walther Flemming

    • Discovered mitosis when he was the first biologist to execute a wholly systematic study of the division of chromosomes



Why DNA technologies

  • Goal was to determine the entire genome sequence and use it to differentiate between individuals as well as to identify the presence of genes involved in causing disease

    • Can we tell people apart

    • Ability to recombine DAN to create new possibilities in genetically modified plants and animals

    • Gene therapies, genetic testing and cloning methods were also developed



  • Human Chromosomes/Genomes

    • Female, XX

    • Male, XY

      • Y is the masculine traits

    • 23 pairs, 46 total



  • First completed in 1990 using DNA from 4 persons

    • Human Genome Project

    • Finding the life's code



  • Purpose of Human Genome Project

    • Identify all the genes

    • Figure out where all the genes

    • Determine the sequences

    • Use this information to help cure diseases and advance medicine

    • Can have ethical and social issues from this project



  • How HGP works

    • Cloned genomes, a bunch of DNA

    • They are sheared into sizes and are unordered, is cut up

    • A computer assembles it

    • Overlapping sequence segments combine to construct the genome

    • Genes have to be identified from the sequence

      • Needs DNA sequences (compute), vitally important to have these



  • Humans have 21,000 genes

    We still don't understand 42% of the genes we have, 58% has been given function



    Genome Comparisons

    • Chimpanzees are 98.8% similar to humans.

    • 99.9% similar to each other



  • DNA Fingerprinting

    • A method to determine differences in specific sequences of genes by using restriction enzymes to produce a pattern unique to an individual

    • Pattern produced is all "Restriction Fragment Length Polymorphism" (Rif-Lip)

    • Most individuals will produce a unique DNA pattern

    • Used in crime cases, paternity cases



  • Restriction Enzyme

    • Recognizes a sequence, and cuts through it

    • Then Run a gel

      • Run an electric current through a gel and let the DNA migrate



  • Why are RFLPS useful in criminal cases

    • Everyone's DNA is different, different fragment lengths will be produced from different people

    • Comparison of the gel electrophoresis rom samples from the crime scene with sampled from suspects can effectively rule people out or provide strong evidence of guilt



  • Polymerase Chain Reaction (artificial DNA replication)

    • Use of a set or primers to amplify a specific sequence in the DNA and make multiple copies of it

    • To allow the reaction to occur in lab, nucleotides and DNA polymerase are added with primers to a DNA sample of interest

    • Once reactions is complete, the sample is subjected to electrophoresis to identify the DNA badn

    • Allows very small samples od DNA (drop of blood) to be increase for further analysis

    • Useful in crime scenes to identify suspected individuals



  • Steps

    • Denaturation

    • Annealing

    • Extension



  • Cycle 1 yields 2 molecules

    Cycle 2 yields 4 molecules

    Cycle 3 yields 8 molecules



    Recombinant DNA technologies

    • DNA from different organisms can be combined to allow expression of genes from one organism to another

    • Possible because genetic code is universal

      • DNA nucleotide are found in all organisms and are universally recognized

    • Allows for bacterial genes to be expressed in plants, fish genes in animals and insect genes in animals

    • Called Genetic engineering



  • Examples

    • First group to recombine DNA were bacteria

    • Creating Insulin from bacteria

      • Genes of interest were cloned and expressed to produce human growth hormone, insulin and other proteins

    • In plants

      • GMO's were produced

    • Creating a plant that’s resistant from cold

      • Took DNA from fish that survives in cold environments

    • In monkeys, a jellyfish gene was introduced



  • How to recombined DNA in a Bacterium

    • Inset gene of interest into plasmid

    • Insert plasmid into bacterial cell

    • Host cell grows and replicates into multiple cells with gene of interest



  • How Genetic Engineering is performed

    • Restrictive enzyme cuts sugar phosphate backbones

    • DNA fragment added, base pairing occurs

    • DNA ligase seals strand



  • Who oversees the safety of GM foods in Canada

    • Canadian food inspection agency

    • Environment Canada

    • Health Canada



  • Example of GM Animals approved for use

    • Expression of growth hormones in salmon to make them grow faster

      • What if the growth hormone gene got into another animal?

      • Salmon has to constantly eat in order to grow



  • Genetic Testing

    • Allows a person's DNA to be tested for the presence of genes that could cause cancer, diabetes, alzheimers and other problems

    • Used in fetuses to test for Down's syndrome and other chromosome abnormalities

    • It is not a predictor of intelligence or other attributes not related to specific traits or diseases

    • Testing must be followed by genetic counseling as well as a consideration of ethical, moral and religious issues before a decision is made to take action using the result



  • Types of genetic Testing

    • Designed to examine single nucleotide mutations or multiple chromosomal errors

    • Determine carrier status

    • Diagnose specific disorder

    • Test prenatally for conditions

    • Determine future risks



  • Prenatal Genetic Testing

     For screening

    • Maternal blood serum

    • Ultrasound

    • Non-invasive prenatal testing

  • For diagnosing

    • Chorionic villus sampling

    • Amniocentesis



  • What is Genetic Testing and What can you with it

    • Diagnose disease

    • Pinpoint genetic factors that caused disease

    • Predict how severe disease might be

    • Choose best medicine and dosage

    • Discover genetic factors that increase your disease risk

    • Find genetic factors that could be passed to children

    • Screen newborns for certain treatable conditions





  • Gene Therapy

    • Replacement of a nonfunctional allele of a gene with a functional allele

      • To cure disease

    • The new version of a gene is introduced into human cells using a virus vector. Must be expressed in the cell and the modified cells replicated

    • Has not proved to be a very successful technique yet



  • Replacing a non-functioning gene suing gene therapy

    • Cystic fibrosis, hemophilia



  • Personalized Medicine

    • Use of medical approaches specifically tailored to individuals base on their genetic profile (DNA sequence)



  • Cloning of Animals

    • Production of an individual entirely from a somatic cell

      • Used to create Dollly the sheep

      • Result is a genetically identical copy of the parent from which the somatic cell was derived

    • Can be used if a superior animal was needed to be clones

      • Superfast horse or fast egg-laying hen

    • But the clone animal also had features of the older parents

      • Developed arthritis and cells had shorter telomere regions

      • Behaved like an older 2 year old

      • An old person in a young body

    • Clone cat CC had a different personality from the mother



  • Implications of DNA technology

    • Muse be considered carefully in a balance with moral, societal, ethical and religious beliefs

    • Ability to alter DNA should be considered cautiously

    • While is it proving to be beneficial for medical applications, it should not be use frivolously

    • There is a risk of genetic discrimination occurring where individuals who are known carriers of disease-causing genes may be denied opportunities



  • Restrictions Placed on Use of DNA technology

    • Humans cannot be cloned

    • Genetic engineering of humans is not allowed

    • Research on human cells, stem cells requires special permits

    • Research on recombinant DNA requires special permits

    • Mamy ethical and scientific regulations on conducting research involving human subjects