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  • Genetic Switches

    Genetic Switches

    Click & Learn

    Learn about how gene switches can control expression of genes in different tissues.

  • 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.

  • Paintbrush Gene

    Paintbrush Gene

    Animations

    (49 sec) In two related Drosophila species, a so-called paintbrush gene is activated to "paint" the pigment on the body. In one species, an extra switch activates the gene, resulting in spotted wings.

  • Pitx1 Expression

    Pitx1 Expression

    Animations

    (55 sec) In the stickleback fish, pelvic-fin reduction resulted from changes in the regulatory switch elements of the Pitx1 gene. In the marine ancestor, the Pitx1 gene is activated in the pelvic-fin region during development to generate the fin. In the pelvic-reduced stickleback, the regulatory switch that normally turns on the Pitx1 gene is either missing or non-functional.

  • 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.

  • Classroom Activities: Pedigree Analysis Activity

    Classroom Activities: Pedigree Analysis Activity

    Activities

    To accompany the lecture series Learning from Patients: The Science of Medicine.

  • The p53 Gene and Cancer

    The p53 Gene and Cancer

    Click & Learn

    This Click and Learn explains the structure and function of the p53 protein as well as how the protein’s activity is regulated.

  • Learning from Mice: The Science of Transgenic Technology

    Learning from Mice: The Science of Transgenic Technology

    Clips

    (11 min 8 sec) What do humans, flies, and worms have in common? More than you might think. See how transgenic organisms are engineered, and how they enable researchers to study genetic diseases.

  • 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.

  • Translation (advanced detail)

    Translation (advanced detail)

    Animations

    (3 min 4 sec) Messenger RNA (mRNA) carries DNA's genetic information to the ribosome, where it is translated into a sequence of amino acids. mRNA is fed into the ribosome, and it is positioned so that it can be read in groups of three letters, known as codons. Each mRNA codon is matched against the transfer RNA molecule's anti-codon. If there is a match, the amino acid carried by the transfer RNA is added to the growing protein chain. Also available in Spanish.

  • Translation (basic detail)

    Translation (basic detail)

    Animations

    (2 min 6 sec) The ribosome is a molecular factory that translates the genetic information in RNA into a string of amino acids that becomes a protein. Inside the ribosome, the genetic code of the RNA is read three letters at a time and compared with the corresponding code on a transfer molecule. When a match occurs between the codes, the amino acid carried by the transfer molecule is added to the growing protein chain. Also available in Spanish.

  • 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.

  • Sickle Cell Anemia

    Sickle Cell Anemia

    Animations

    (1 min) Sickle cell anemia is a genetic disease that affects hemoglobin.

  • Shotgun sequencing

    Shotgun sequencing

    Animations

    (1 min) In shotgun sequencing many copies of the entire genome are "blown up" into millions of small fragments. Each small fragment is sequenced. Powerful computers then assemble the individual fragments into the original configuration. Repeat sequences pose a problem for this approach because their sizes can be much larger than the small fragments.

  • 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.

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