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  • The Y Chromosome

    The Y Chromosome

    Animations

    (2 min 46 sec) The Y chromosome has been likened to a hall of mirrors because its sequence contains many sections that appear to be palindromes. These palindromes provide a clue to some interesting events that may have occurred during the course of the chromosome's evolution.

  • X Inactivation

    X Inactivation

    Animations

    (55 sec) This animation shows how the random deactivation of one of the X chromosomes in a pair can lead to a mozaicism in the expression genes. 

  • Zebrafish Heart Regeneration

    Zebrafish Heart Regeneration

    Animations

    (2 min 30 sec) The zebrafish heart is similar to the human heart in many respects. But unlike the human heart, the fish heart closes wounds rapidly and then regenerates to nearly full function. Fibroblast growth factor (FGF) is an important molecule in the regeneration process.

  • Viral Lifecycle

    Viral Lifecycle

    Animations

    (1 min 8 sec) Delivering a single virus to a cell allows the virus to infect the cell, replicate, and give rise to many progeny viruses. These viruses can then infect many neighboring cells. Also available in Spanish.

  • Viral Geometry and Structural Diversity

    Viral Geometry and Structural Diversity

    Animations

    The geometric structures of viruses are beautiful and can be used, along with genomic information, to identify them.

  • VEGF

    VEGF

    Animations

    This animation shows how a growing tumor can recruit nearby blood vessels in order to gain a supply of blood.

  • Using p53 to Fight Cancer

    Using p53 to Fight Cancer

    Animations

    (1 min 2 sec) This animation demonstrates how cancerous cells could be destroyed using a modified virus.

  • Tri Nucleotide Repeat

    Tri Nucleotide Repeat

    Animations

    (1 min 8 sec) Slippage during DNA replication can lead to expanding sections of repeating nucleotides. Watch this animation to see how this problem occurs. 

  • Cloning an Army of T Cells for Immune Defense

    Cloning an Army of T Cells for Immune Defense

    Animations

    (4 min 21 sec) View the animation to see how one type of immune cell—the helper T cell—interprets a message presented at the surface of the cell membrane. The message is an antigen, a protein fragment taken from an invading microbe. A series of events unfolds that results in the production of many clones of the helper T cell. These identical T cells can serve as a brigade forming an essential communication network to activate B cells, which make antibodies that will specifically attack the activating antigen.

  • Fossil Record of Stickleback Evolution

    Fossil Record of Stickleback Evolution

    Clips

    (2 min 34 sec) A quarry site in Nevada carries the evolutionary history of a population of stickleback fish that resided there when it was a freshwater lake.

  • 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.

  • Somatic Cell Nuclear Transfer Animation

    Somatic Cell Nuclear Transfer Animation

    Animations

    (52 sec) Somatic cell nuclear transfer (SCNT) is a technique for cloning. The nucleus is removed from a healthy egg. This egg becomes the host for a nucleus that is transplanted from another cell, such as a skin cell. The resulting embryo can be used to generate embryonic stem cells with a genetic match to the nucleus donor (therapeutic cloning), or can be implanted into a surrogate mother to create a cloned individual, such as Dolly the sheep (reproductive cloning).

  • Intracellular Infection by Salmonella

    Intracellular Infection by Salmonella

    Animations

    (1 min 19 sec) In this animation, you can see how one S. typhimurium invades an epithelial cell of the intestinal tract, survives the intracellular defense mechanisms of the host cell, and multiplies.

  • RNA Folding

    RNA Folding

    Animations

    (33 sec) Since RNA is single-stranded, it can fold upon itself and form structures that are protein-like in both appearance and functionality.

  • 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.

  • Recombination of Viral Genome

    Recombination of Viral Genome

    Animations

    (3 min 5 sec) When two different strains of influenza infect a single cell, their genetic material can mix freely, resulting in a new third strain of influenza.

  • Meiosis

    Meiosis

    Animations

    (5 min 53 sec) Meiosis, the form of cell division unique to egg and sperm production, sets the stage for sex determination by creating sperm that carry either an X or a Y sex chromosome. But what is it about the X or Y that determines sex? Also available in Spanish.

  • Mismatch Repair

    Mismatch Repair

    Animations

    (1 min 22 sec) This animation illustrates how mistakes made during DNA replication are repaired.

  • The Proteasome

    The Proteasome

    Animations

    (1 min 44 sec) A 3D animation showing how proteins in the cell are tagged for disposal and degraded by the proteasome.

  • Protease inhibitors

    Protease inhibitors

    Animations

    (1 min 6 sec) Protease inhibitors prevent maturation of viral proteins inside HIV particles.

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