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Showing 21-40 of 43 Resources
  • Eavesdropping on Tiny Conspiracies

    Eavesdropping on Tiny Conspiracies

    Lecture

    (58 min 29 sec) The quorum sensing system is a target for a new class of drugs that interfere with virulence without killing bacteria.

  • Demonstration: Quorum sensing molecules

    Demonstration: Quorum sensing molecules

    Clip

    (50 sec) Quorum sensing signal molecules have parts that are common between species as well as species-specific parts.

  • The LUX operon controls light production

    The LUX operon controls light production

    Animation

    (2 min 25 sec) A single transcription factor controls this operon, which contains five genes necessary to produce bioluminescence.

  • Lightning-strike cabal acts like a Taser

    Lightning-strike cabal acts like a Taser

    Animation

    (2 min 9 sec) Some cone snail toxins chemically hyperactivate neurons and immobilize prey, much like a Taser.

  • Signal molecules trigger transcription factors

    Signal molecules trigger transcription factors

    Animation

    (2 min 4 sec) Varying concentrations of a signaling molecule activate different transcription factors and determine cell fate.

  • AZT blocks reverse transcriptase

    AZT blocks reverse transcriptase

    Animation

    (1 min 46 sec) HIV's reverse transcriptase mistakes AZT for thymidine. Once incorporated, AZT stops reverse transcription.

  • 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.

  • Gleevec

    Gleevec

    Animation

    (1 min 4 sec) Gleevec is a drug designed to interfere with the stimulation of growth in leukemia cells. This 3D animation shows how this is achieved.

  • 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.

  • Pauling triple helix model

    Pauling triple helix model

    Animation

    (29 sec) One of the failed hypothetical models of DNA is Linus Pauling's triple helix model. This structure would be unstable under normal cellular conditions.

  • 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.

  • CML and Gleevec

    CML and Gleevec

    Animation

    (41 sec) Chronic myeloid leukemia (CML) is caused by a mutation that leads to an abnormal protein that is always active. The drug Gleevec has a shape that fits into the active site of the abnormal protein and stops its harmful effects.

  • 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.

  • Myosin II Mechanism

    Myosin II Mechanism

    Animation

    (57 sec) Myosin II is one of the molecules involved in furrow formation in dividing cells. This animation shows how the molecule operates, and how furrowstatin blocks the mechanism and halts division of a cell.

  • Diffusion Across Membranes

    Diffusion Across Membranes

    Animation

    (4 sec) This animation describes two different ways by which chemicals migrate through membranes: passive diffusion and active transport.

  • Life at the End of the Chromosome: Another RNA Machine

    Life at the End of the Chromosome: Another RNA Machine

    Lecture

    (58 min 20 sec) The chromosome ends, or telomeres, are necessary for DNA stability and replication.

  • How to Accelerate a Reaction 100,000,000,000 Times Using Only RNA

    How to Accelerate a Reaction 100,000,000,000 Times Using Only RNA

    Lecture

    (58 min 29 sec) Studies of RNA catalytic centers have revealed much about their structure and mode of action.

  • RNA as an Enzyme: Discovery, Origins of Life, and Medical Possibilities

    RNA as an Enzyme: Discovery, Origins of Life, and Medical Possibilities

    Lecture

    (58 min 22 sec) Discovery of RNA's catalytic activity led to unexpected spin-offs, including a new scenario for the origin of life.

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