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  • Visualizing Gene-Expression Patterns

    Visualizing Gene-Expression Patterns

    Click & Learn

    Learn about the different ways scientists are able to detect when genes are being expressed in various tissues.

  • Watson constructing base pair models

    Watson constructing base pair models

    Clip

    (1 min 42 sec) During the process of trying to elucidate the structure of DNA, Jim Watson made some cardboard models to try to understand how DNA nucleotides are paired. It helped him visualize how hydrogen atoms of paired nucleotides interact with each other to form a symmetrical structure that fits the double helix model.

  • Polymerase chain reaction

    Polymerase chain reaction

    Animation

    (1 min 28 sec) Polymerase chain reaction, or PCR, is a technique for making many copies of a specific DNA sequence. DNA is repeatedly heated and cooled in the presence of primers that bracket the desired sequence and of the enzyme Tac polymerase. In as few as 30 cycles, a billion copies of the target sequence can be made.

  • Damage to DNA leads to mutation

    Damage to DNA leads to mutation

    Animation

    (1 min 7 sec) Reactive molecules, such as free radicals, and solar ultraviolet radiation can lead to mutations in DNA. Most mutations are corrected, but in rare cases mutations can accumulate and cause diseases such as cancer.

  • Chargaff's Ratio

    Chargaff's Ratio

    Animation

    (49 sec) In 1950, Erwin Chargaff published a paper stating that in the DNA of any given species, the ratio of adenine to thymine is equal, as is the ratio of cytosine to guanine. This became known as Chargaff's ratio, and it was an important clue for solving the structure of DNA.

  • Building blocks of DNA

    Building blocks of DNA

    Animation

    (27 sec) Adenine (A), cytosine (C), guanine (G), and thymine (T) are the components of nucleic acid that make up DNA.

  • The Double Life of RNA

    The Double Life of RNA

    Lecture

    In four lectures, Nobel laureate Thomas R. Cech, PhD, discusses the ability of RNA to act as more than just an intermediary between DNA and proteins.

  • Enzymes That Are Not Proteins: The Discovery of Ribozymes

    Enzymes That Are Not Proteins: The Discovery of Ribozymes

    Clip

    (19 min 4 sec) Listen to past HHMI President Dr. Thomas Cech discussing his Nobel Prize-winning discovery of RNA's catalytic properties.

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