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Frontiers of Biotechnology


Frontiers of Biotechnology Manipulating DNA Biotechnology is used to identify people, produce transgenic organisms and clones, study diseases and evolution, and ... – PowerPoint PPT presentation

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Title: Frontiers of Biotechnology

Frontiers of Biotechnology
Manipulating DNA
  • Biotechnology is used to identify people, produce
    transgenic organisms and clones, study diseases
    and evolution, and create medical treatments for
    people with life threatening diseases.

Techniques to Manipulate DNA
  • Scientists must be able to work with DNA without
    being able to see or handle it directly.
  • Scientists use artificial nucleotides, artificial
    genes, chemical mutagens, computers, enzymes,
    bacteria, and many other techniques to manipulate

Spooled DNA
Restriction Enzymes
  • Restriction enzymes are enzymes that cut DNA
    molecules at specific nucleotide sequences.
  • Any time the restriction enzyme comes across the
    specific nucleotide sequence, it cuts the DNA.
  • This allows scientists to work with small pieces
    of DNA at a time.
  • Restriction enzymes are produced naturally by
    bacteria to cut the DNA of invading viruses.
  • Restriction enzymes can either make clean cuts
    (blunt ends) of the DNA or leave sticky ends
  • The sticky ends are staggered cuts in the DNA,
    that allow the DNA to reform easily.

Restriction Maps
  • Gel Electrophoresis
  • Once DNA has been cut by restriction enzymes, it
    is placed into a gel electrophoresis plate.
  • Gel electrophoresis uses an electrical current to
    separate a mixture of DNA fragments from each
  • A positive electrode is set at one end, and a
    negative electrode is set at the opposite end.
  • Because DNA has a negative charge, the fragments
    move toward the positive end.
  • The larger fragments move slower than the smaller
    fragments, therefore the length of the DNA
    fragment can be estimated by the distance it
    travels through the gel in a certain period of

Restriction Maps
  • Restriction maps use gel electrophoresis to show
    the lengths of DNA fragments between restriction
    sites in a strand of DNA.
  • Restriction maps are used to study mutations.
  • They will show if nucleotides have been added or
    deleted from a particular strand of DNA.
  • Or, a mutation may lead to a restriction site,
    and the DNA would not be cut in the same place.

Copying DNA
  • Forensic scientists use DNA from cells in a
    single hair at a crime scene to identify a
  • Doctors test a patients blood to quickly detect
    the presence of bacteria that causes Lyme
  • Scientists compare DNA from different species to
    determine how closely the species are related.
  • If the original DNA from any of these sources is
    too small to accurately study, the samples of DNA
    must be increased, or amplified, so that they can
    be analyzed.

Polymerase Chain Reaction
  • PCR is a technique that produces millionsor even
    billionsof copies of a specific DNA sequence in
    just a few hours.
  • It is a very simple process.
  • There are four materials involved the DNA to be
    copied, DNA polymerases, large amounts of each of
    the four nucleotides (A, T, C, G), and two
  • A primer is a short segment of DNA that acts as
    the starting point for a new strand.
  • Each PCR cycle doubles the number of DNA copies.
    The original piece of DNA becomes two copies.
    Those two copies become fourect.

PCR Process
  • 1. Separating.
  • The container with all the reactants is heated to
    separate the double-stranded DNA into single
  • 2. Binding.
  • The container is cooled and the primers bind to
    their complimentary DNA sequences. One primer
    binds to each DNA strand. The primers bind on the
    opposite ends of the DNA segment being copied.
  • 3. Copying.
  • The container is heated again and the polymerases
    begin to build new strands of DNA. Added
    nucleotides bind to the original DNA strands by
    complimentary base pairing. The polymerases
    continue attaching nucleotides until the entire
    DNA segment has been copied.

DNA Fingerprinting
  • DNA evidence is used to convict a criminal,
    release an innocent person from prison, or solve
    a mystery.
  • A couple of decades ago, the lines and swirls of
    someones fingertip were a detectives best hope
    for identifying someone. Now, investigators
    gather biological samples and analyze DNA for
    another kind of evidence a DNA fingerprint.

DNA Fingerprinting
  • A DNA fingerprint is a kind of restriction map.
  • It is a representation of parts of an
    individuals DNA that can be used to identify a
    person at a molecular level.
  • People differ greatly in the number of repeated
    non-coding sequences of DNA.
  • DNA fingerprints can also be used to show
    relationships between family members.
  • The children have similar DNA fingerprints to
    each other, but they are not identical. Also,
    their DNA fingerprints are combinations of the
    DNA fingerprints of the parents.

DNA Fingerprinting and Identification
  • The reliability of DNA identification relies on
  • Ex. Suppose that 1 in every 500 people has three
    copies of the repeat at location A.
  • That means that any person has a 1 in 500 chance
    of having a matching DNA fingerprint for that
    region of their chromosome.
  • Then, suppose that 1 in 90 people has six copies
    of the repeat sequence at location B, and 1 in
    120 people has ten copies of the repeat sequence
    at location C.
  • Individual probabilities are multiplied by each
    other to find total probability. Therefore, when
    the three separate probabilities are multiplied,
    suddenly the chance that two people have the same
    DNA fingerprint is very small.
  • 1/500 x 1/90 x 1/120 1/5,400,000 1 chance in
    5.4 million people.

Uses of DNA Fingerprinting
  • DNA fingerprinting can be used to convict a
    criminal or set an innocent person free.
  • The Innocence Project has successfully released
    249 wrongly convicted people from jail using DNA
  • DNA fingerprinting can be used to identify
    familial relationships (paternity).
  • DNA fingerprinting is also used to study
    biodiversity in an area, identify genetically
    engineered crops, and to follow migration
    patterns of native species.

Larry Fuller spent 18 years in prison, after
being wrongfully convicted of aggravated rape in
1981. Fuller was excluded as the rapist after
advanced DNA testing. He was released in January
Genetic Engineering
  • Glowing mice are used in cancer research, glowing
    plants are used to track genetically modified
    crops, and in 1999, British researchers
    introduced glowing yeast cells.
  • The glowing yeast cells can detect pollution in
    an environment.
  • Under normal conditions, the cells do not glow,
    but when they come into contact with certain
    chemicals, they glow.
  • This indicated areas that need to be cleaned up.

  • A clone is a genetically identical copy of a gene
    or of an organism.
  • Cloning can be a natural process.
  • Plants can clone themselves, bacteria produce
    genetically identical copies of themselves, and
    identical twins are clones of each other.
  • To clone a mammal, scientists swap DNA between
    cells with a technique called nuclear transfer.
  • 1. An unfertilized egg is taken from an animal,
    and the eggs nucleus is removed.
  • 2. The nucleus of a cell from the animal to be
    cloned is implanted into the egg.
  • 3. The egg is stimulated, and if the transfer is
    successful, the egg will begin dividing.

Dolly The First Clone
  • Born July 5th, 1996 in Endinburgh, Scotlandwas
    the fist cloned mammal (cloned from a mammary
    gland, and named after Dolly Parton)
  • She was the only lamb who survived to adulthood,
    out of 227 attempts.
  • She gave birth to 6 lambs, and died at the age of
    6 due to lung disease.

The Future of Cloning
  • In January 2009, scientists in Spain successfully
    cloned a Pyrenean Ibexa species declared extinct
    in 2000.
  • They used skin cells preserved in liquid
  • The Ibex died shortly after birth due to physical
    defects in its lungs.
  • The possibility of cloning other endangered or
    extinct species (like the wooly mammoth or
    dinosaurs) is closer.
  • This still does not increase genetic diversity in
    breeding pools however, and does not help loss of

Genetic Engineering
  • Genetic research relies on cloning, but not of
    entire organisms.
  • Instead, the cloning of individual genes is used
    to make a copy of one segment of DNA.
  • In some cases, scientists insert cloned genes
    from one organism into an entirely different
  • Genetic engineering is when you change an
    organisms DNA to give an organism new traits.
  • Genetic engineering is only possible because the
    genetic code is shared by all organisms.

Recombinant DNA
  • Recombinant DNA is DNA that contains genes from
    more than one organism.
  • To create recombinant DNA, scientists often used
    plasmids located in bacteria.
  • Plasmids are closed loops of DNA within the
    bacteria that are easily manipulated.
  • Scientists are using recombinant DNA to
  • Try to create crop plants that produce medicines
    and vitamins.
  • Try to create vaccines against HIV.
  • Make hormones like HGH, insulin, and oxytocin.
  • Use in gene therapy.
  • ETC!

Transgenic Organisms
  • A transgenic organism has one or more genes from
    another organism inserted into the genome.
  • Ex. The gene for human insulin can be put into
    plasmids. The plasmids are inserted into
    bacteria. The transgenic bacteria make human
    insulin which can be collected and used to treat
    people with diabetes.

Transgenic Plants
  • Scientists create transgenic plants by inserting
    a gene into a bacterias plasmid and having the
    bacteria infect a plant. The infected plant will
    then incorporate the new gene into its DNA.
  • This technique has allowed scientists to give
    plants new traits, such as resistance to frost,
    diseases, and insects.
  • This increases crop yields, more food is produced
    more quickly and cheaply.
  • Genetically modified (GM) foods, are now common
    in the United States.

Transgenic Animals
  • Transgenic animals are difficult to make. It take
    many trials (hundreds) before a transgenic animal
    will form correctly to adulthood.
  • The advantage with transgenic animals is that the
    transgenic gene will be present in ALL of their
    DNA, including in their reproductive cell. So,
    transgenic traits will be passed on to the next
  • Transgenic mice are often used as models to study
    human development and disease.
  • They are used to study cancer (oncomice),
    diabetes, brain function and development, sex
    determination, etc.
  • Other mice are called gene knockout mice.
  • These mice are used to student gene functions and
    point mutations.

Concerns About Genetic Engineering
  • There are concerns regarding human health and the
  • People routinely eat GM foods without knowing it.
    Scientists have not been able to discover any
    adverse health effects so far.
  • Critics claim that not enough research has been
    done on possible allergic reactions or other
    unknown side effects.
  • Another concern is that GM plants may cause bees
    and butterflies to go extinct (by transgenically
    producing pesticides).
  • Transgenic plants may also cross-pollinate with
    wild natural plants.
  • Finally, transgenic plants may decrease genetic
    diversity in crops and leave them more vulnerable
    to new diseases or pests.
  • Another concern is about the ethics of genetic
    engineering in the first place.

  • Genomics is the study of genomes, which can
    include the sequencing of all of an organisms
  • This is how we know that humans and chimpanzees
    share 99-98 of their DNA.
  • Comparing DNA from many people at one time helps
    researchers find genes that cause disease, and it
    helps them understand how medication works.
  • Biologists study DNA of different species to
    learn how closely related they are to each other
    and to extrapolate how far back in the
    evolutionary time line they diverged.

DNA Sequencing
  • All genomic studies begin with DNA sequencing.
  • This is determining the order of DNA nucleotides
    in genes or in genomes.
  • PCR is one method.
  • Humans do not have the largest genome. Vanilla
    plants, crested newts, and lungfish are among the
    many organisms who have a larger genome than us!

The Human Genome Project
  • There are 30,000-40,000 genes in the human
  • Each gene represents about 100,000 DNA bases.
  • The Human Genome Project has two goals
  • 1. To map and sequence all of the DNA base pairs
    of the human chromsomes.
  • 2. To identify all of the genes within the
  • Right now, the Human Genome Project is working on
    the HapMapthe study of how DNA sequences vary
    among people.
  • This will hopefully identify genetic differences
    that play a part in human diseases.

  • Bioinformatics is the use of computer databases
    to organize and analyze biological data.
  • Bioinformatics give scientists a way to store,
    share, and find data.

Genetic Screening
  • Genetic screening is the process of testing DNA
    to determine a persons risk of having or passing
    on a genetic disorder.
  • It often involved both pedigree analysis and DNA
  • There are tests for about 900 genetic disorders,
    including cystic fibrosis, Duchennes muscular
    dystrophy, and breast cancer.

Gene Therapy
  • Gene therapy is the replacement of a defective or
    missing gene, or addition of a new gene, into a
    persons genome to treat a disease.
  • Scientists will often use de-natured viruses to
    introduce the new gene to the body.
  • There have been a few successful cases of gene
    therapy wiping out diseases.
  • There are many experiments going on with gene
  • Scientists are trying to insert genes into the
    immune system that stimulated the immune system
    to attack cancer cells.
  • Another method is to insert suicide genes into
    cancer cells.