How did the human Y chromosome become so small relative to its X counterpart? This animation depicts the 300-million-year odyssey of the sex chromosomes that began when the proto X and Y were an identical pair.
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.
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.
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.
This "morph" animation demonstrates how the expression of a particular toolkit gene in a butterfly larva corresponds to the location of the wing eyespots in an adult butterfly.
A sample is put on a Virochip microarray, and results are compared to databases of all known viral sequences.
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.
The geometric structures of viruses are beautiful and can be used, along with genomic information, to identify them.
This animation shows how a growing tumor can recruit nearby blood vessels in order to gain a supply of blood.
This animation illustrates how a small molecule binds to a protein. As a result of the binding, the protein alters its shape and becomes inactivated.
This animation demonstrates how cancerous cells could be destroyed using a modified virus.
A visual representation of the U.S. AIDS epidemic from 1981 to 1997. Each dot represents 30 cases.
Slippage during DNA replication can lead to expanding sections of repeating nucleotides. Watch this animation to see how this problem occurs.
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...
This animation shows a rotating 3-D image of a stickleback skeleton. The pelvic region, including the pelvic spines, is highlighted in red. Armored plating covers the flanks of the fish. The three prominent dorsal spines give the fish its name.
A molecular menagerie of small molecules is displayed, with two particular molecules singled out for attention: rapamycin and furrowstatin, which are discussed in the remainder of Dr. Schreiber's lectures on chemical genetics.
Microarray technology is useful for screening many small molecules at once. Automated devices have made it possible for thousands of different small molecules to be printed as an array of spots on a glass slide. A single type of protein which has been tagged with a fluorescent marker can then be...
Varying concentrations of a signaling molecule activate different transcription factors and determine cell fate.
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...
In mammals, the controlling clock component that generates a 24-hour rhythm is the suprachiasmatic nucleus (SCN), located in a part of the brain called the hypothalamus. The SCN produces a signal that can keep the rest of the body on an approximately 24-hour schedule. This animation illustrates...
Illustrates how studying one family's pedigree can reveal an entire history of passing on a genetic disorder such as SCA1.
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.
Since RNA is single-stranded, it can fold upon itself and form structures that are protein-like in both appearance and functionality.
HIV's reverse transcriptase mistakes AZT for thymidine. Once incorporated, AZT stops reverse transcription.
The growth cone of a neuron avoids repellant molecules and navigates to innervate the appropriate muscle.