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  • Biology Chapter 9 &

    Honors Biology Chapter 13

    Frontiers

    Of

    Biotechnology

  • DNA TECHNOLOGY IS ABOUT:

    Manipulating DNA for mans purposes.

    It includes: cutting DNA, Gel Electrophoresis and

    Polymerase Chain Reactions

    Scientists use several techniques

    to manipulate DNA.

  • How do you cut DNA?

    Restriction enzymes cut DNA at a specific nucleotide

    sequence called a restriction site.

    Restriction enzymes act as molecular scissors.

    come from various types of bacteria

    allow scientists to more easily study and manipulate

    genes

    DNA TECHNIQUE #1: Cutting DNA

  • Different restriction enzymes cut DNA in different

    ways.

    each enzyme has a different restriction site

    DNA chemical bonds are broken in the cutting

  • some cut straight across and leave blunt ends

    some make staggered cuts and leave sticky ends

    = have overhanging nucleotides

  • 9.1 Manipulating DNA

    Restriction Enzyme Activity

    http://www.classzone.com/cz/books/bio_07/get_chapter_gro

    up.htm?cin=3&ci=9&rg=animated_biology&at=animated_bio

    logy&npos=2&spos=9&var=animated_biology

    http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=3&ci=9&rg=animated_biology&at=animated_biology&npos=2&spos=9&var=animated_biology

  • DNA TECHNIQUE #2: Gel Electrophoresis

    Gel electrophoresis is used to separate DNA

    fragments by size.

    A DNA sample is cut with restriction enzymes.

    Uses Electrical current to pull DNA fragments

    through a gel.

  • Smaller fragments travel faster and travel farther

    than longer, larger fragments.

    Fragments of different

    sizes appear as

    bands on the gel.

  • A restriction map shows the lengths of DNA fragments

    between restriction sites.

    only indicate size,

    not DNA sequence

    useful in genetic

    engineering

    used to study

    mutations

  • 9.1 Manipulating DNA

    KEY CONCEPT

    DNA fingerprints identify people at the molecular

    level.

  • 9.1 Manipulating DNA

    A DNA fingerprint is a type of restriction map.

    DNA fingerprints are based on parts of an individuals

    DNA that can by used for identification.

    based on noncoding regions of DNA

    noncoding regions have repeating DNA sequences

    number of repeats differs between people

    banding pattern on a gel (from gel electrophoresis is

    a DNA fingerprint

  • 9.1 Manipulating DNA

  • 9.1 Manipulating DNA

    DNA fingerprinting is used for identification.

    DNA fingerprinting depends on the probability of a

    match.

    Many people have the

    same number of

    repeats in a certain

    region of DNA.

    The probability that two

    people share identical

    numbers of repeats in

    several locations is

    very small.

    (mother) (child 1) (child 2) (father)

  • 9.1 Manipulating DNA

    Individual probabilities are multiplied to find the

    overall probability of two DNA fingerprints randomly

    matching.

    Several regions of DNA are

    used to make DNA fingerprints.

    1 1 1 1

    500 90 120 5,400,0001 chance in 5.4 million peoplex x = =

  • 9.1 Manipulating DNA

    DNA fingerprinting is used in several ways.

    evidence in criminal

    cases

    paternity tests

    immigration requests

    studying biodiversity

    tracking genetically

    modified cropsEx. Tortoise species are

    identified with DNA

    fingerprinting to determine

    which Galapagos Island they

    came from, so raised tortoises

    may be reintroduced to their

    Native islands to increase

    their numbers. (San Diego Zoo)

  • KEY CONCEPT

    The polymerase chain reaction (PCR) rapidly

    copies segments of DNA.

  • PCR uses polymerases to copy DNA segments.

    PCR makes many copies of a specific DNA sequence in a

    few hours.

    target sequence of DNA

    PCR amplifies DNA samples.

    PCR is similar to DNA replication.

  • PCR is a three-step process.

    PCR uses four materials.

    DNA to be copied

    DNA polymerase

    A, T, C, and G nucleotides

    two primers

    = short strands

    of DNA to

    build the new

    strands on,

    act like

    bookends

    DNA strands

    polymerase

    nucleotides

    primer 1

    primer 2

  • 9.1 Manipulating DNA

    PCR animation

    http://www.classzone.com/cz/books/bio_07/get_chapter_

    group.htm?cin=3&ci=9&rg=animated_biology&at=animat

    ed_biology&npos=2&spos=9&var=animated_biology

    http://www.classzone.com/cz/books/bio_07/get_chapter_group.htm?cin=3&ci=9&rg=animated_biology&at=animated_biology&npos=2&spos=9&var=animated_biology

  • DNA strands

    polymerase

    nucleotides

    primer 1

    primer 2

    The three steps of PCR occur in a cycle.

    heat is used to separate double-stranded DNA

    molecules

    primers bind to each DNA strand on opposite ends of

    the segment to be copied

    DNA polymerase binds nucleotides together to form

    new strands of DNA

  • Each PCR cycle doubles the number of DNA molecules.

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