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  • The Chemical Structure of DNA

    The Chemical Structure of DNA

    Animations

    (2 min 44 sec) DNA's chemical properties can be harnessed for a variety of biotechnology applications.

  • Polymerase chain reaction (PCR)

    Polymerase chain reaction (PCR)

    Animations

    (54 sec) PCR is a standard laboratory technique that allows amplification of specific segments of DNA based on complementarity.

  • The LUX operon controls light production

    The LUX operon controls light production

    Animations

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

  • Signal molecules trigger transcription factors

    Signal molecules trigger transcription factors

    Animations

    (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

    Animations

    (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.

  • What Is Fat?

    What Is Fat?

    Posters

    The poster from the 2004 Holiday Lectures on Science, The Science of Fat. See how fat is stored and metabolized. (This poster is designed to printed at a maximum size of 29.5" x 23.5".)

  • How The Body Uses Fat

    How The Body Uses Fat

    Click & Learn

    This slide show explores some of the ways the body processes fat, including digestion, transport, conversion, and energy extraction.

  • Molecular Structure of Fat

    Molecular Structure of Fat

    Click & Learn

    This slide show delves into the various molecular shapes that fat can take.

  • PPAR-gamma Activation in the Fat Cell

    PPAR-gamma Activation in the Fat Cell

    Animations

    (2 min 49 sec) The PPAR-gamma receptor activates certain genes in a fat cell, resulting in the storage of fat and changes in hormone levels.

  • Watson constructing base pair models

    Watson constructing base pair models

    Clips

    (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.

  • Triplet code

    Triplet code

    Animations

    (1 min 8 sec) Once the structure of DNA was discovered, the next challenge was determining how the sequence of letters coded for the 20 amino acids. In theory, one or two letters can only code for 4 or 16 amino acids, respectively. A scheme using three letters, a triplet code, is the minimum necessary to encode for all the amino acids.

  • DNA transcription (advanced detail)

    DNA transcription (advanced detail)

    Animations

    (1 min 55 sec) The process of copying DNA into messenger RNA (mRNA) is called transcription. Transcription factors assemble at the promoter region of a gene, bringing an RNA polymerase enzyme to form the transcription initiation complex. Activator proteins at the enhancer region of DNA then activate the transcription initiation complex. RNA polymerase unzips a small portion of the DNA and copies one strand into an mRNA molecule. Also available in Spanish.

  • DNA transcription (basic detail)

    DNA transcription (basic detail)

    Animations

    (1 min 55 sec) The first phase of the process of reading DNA information to make proteins starts with a molecule unzipping the DNA. The molecule then copies one of the strands of DNA into a strand of RNA, a close cousin of DNA. This process is called transcription. Also available in Spanish.

  • Sanger method of DNA sequencing

    Sanger method of DNA sequencing

    Animations

    (52 sec) Fred Sanger developed the first technique for sequencing DNA. DNA is replicated in the presence of chemically altered versions of the A, C, G, and T bases. These bases stop the replication process when they are incorporated into the growing strand of DNA, resulting in varying lengths of short DNA. These short DNA strands are ordered by size, and by reading the end letters from the shortest to the longest piece, the whole sequence of the original DNA is revealed.

  • DNA replication (advanced detail)

    DNA replication (advanced detail)

    Animations

    (2 min 20 sec) Both strands of the DNA double helix act as templates for the new DNA strands. Incoming DNA is unraveled by the enzyme helicase, resulting in the 3' strand and the 5' strand. The 3' strands and the 5' strands are replicated by a DNA polymerase enzyme but in different ways. Also available in Spanish.

  • DNA replication (basic detail)

    DNA replication (basic detail)

    Animations

    (1 min 7 sec) Using information from molecular research, this 3-D animation shows how DNA is replicated at the molecular level. It involves an enzyme that unwinds the DNA, and other enzymes that copy the two resulting strands. Also available in Spanish.

  • DNA replication (schematic)

    DNA replication (schematic)

    Animations

    (50 sec) The structure of DNA, discovered by James Watson and Francis Crick, suggests a mechanism of replication. The double helix unwinds, and each strand acts as a template for the construction of the new DNA molecule. Also available in Spanish.

  • Polymerase chain reaction

    Polymerase chain reaction

    Animations

    (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.

  • Paired DNA strands

    Paired DNA strands

    Animations

    (1 min 18 sec) DNA has a double helix structure. If untwisted, DNA looks like two parallel strands. Each strand has a linear sequence of A, C, G, and T. The precise order of the letters carries the coded instructions. One strand is a complementary image of the other: A always pairs with T, and C always pairs with G.

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