Lysosomes have powerful enzymes and acids to digest and recycle cell materials.

Ionic and covalent bonds hold molecules, like sodium chloride and chlorine gas, together. Hydrogen bonds among molecules, notably involving water, also play an important role in biology. See image 2519 for an unlabeled version of this illustration. Featured in The Chemistry of Health.

During embryonic development, transcription factors (proteins that regulate gene expression) govern the differentiation of cells into separate tissues and organs. Researchers at Cincinnati Children's Hospital Medical Center used mice to study the development of certain internal organs, including the liver, pancreas, duodenum (beginning part of the small intestine), gall bladder and bile ducts. They discovered that transcription factor Sox17 guides some cells to develop into liver cells and others to become part of the pancreas or biliary system (gall bladder, bile ducts and associated structures). The separation of these two distinct cell types (liver versus pancreas/biliary system) is complete by embryonic day 8.5 in mice. The transcription factors PDX1 and Hes1 are also known to be involved in embryonic development of the pancreas and biliary system. This image shows mouse cells at embryonic day 10.5. The green areas show cells that will develop into the pancreas and/or duodenum(PDX1 is labeled green). The blue area near the bottom will become the gall bladder and the connecting tubes (common duct and cystic duct) that attach the gall bladder to the liver and pancreas (Sox17 is labeled blue). The transcription factor Hes1 is labeled red. The image was not published. A similar image (different plane of the section) was published in: Sox17 Regulates Organ Lineage Segregation of Ventral Foregut Progenitor Cells Jason R. Spence, Alex W. Lange, Suh-Chin J. Lin, Klaus H. Kaestner, Andrew M. Lowy, Injune Kim, Jeffrey A. Whitsett and James M. Wells, Developmental Cell, Volume 17, Issue 1, 62-74, 21 July 2009. doi:10.1016/j.devcel.2009.05.012

Stanford University scientist Vijay Pande decided to couple the power of computers with the help of the public. He initiated a project called Folding@Home, a so-called distributed computing project in which anyone who wants to can download a screensaver that performs protein-folding calculations when a computer is not in use. Folding@Home is modeled on a similar project called SETI@Home, which is used to search for extraterrestrial intelligence.

A protein called kinesin (blue) is in charge of moving cargo around inside cells and helping them divide. It's powered by biological fuel called ATP (bright yellow) as it scoots along tube-like cellular tracks called microtubules (gray).

Thin, hair-like biological structures called cilia are tiny but mighty. Each one, made up of more than 600 different proteins, works together with hundreds of others in a tightly-packed layer to move like a crowd at a ball game doing "the wave." Their synchronized motion helps sweep mucus from the lungs and usher eggs from the ovaries into the uterus. By controlling how fluid flows around an embryo, cilia also help ensure that organs like the heart develop on the correct side of your body.

Ecteinascidin 743 (ET-743, brand name Yondelis), was discovered and isolated from a sea squirt, Ecteinascidia turbinata, by NIGMS grantee Kenneth Rinehart at the University of Illinois. It was synthesized by NIGMS grantees E.J. Corey and later by Samuel Danishefsky. Multiple versions of this structure are available as entries 2790-2797.

A typical animal cell cycle lasts roughly 24 hours, but depending on the type of cell, it can vary in length from less than 8 hours to more than a year. Most of the variability occurs in Gap1. Appears in the NIGMS booklet Inside the Cell.

A scanning electron microscope image of an activated mast cell. This image illustrates the interesting topography of the cell membrane, which is populated with receptors. The distribution of receptors may affect cell signaling. This image relates to a July 27, 2009 article in Computing Life.

Microscopy image of a tongue. One in a series of two, see image 5810

The parasitic worm that causes schistosomiasis hatches in water and grows up in a freshwater snail, as shown here. Once mature, the worm swims back into the water, where it can infect people through skin contact. Initially, an infected person might have a rash, itchy skin, or flu-like symptoms, but the real damage is done over time to internal organs.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Real-time movie of young squids. Squids are often used as research organisms due to having the largest nervous system of any invertebrate, complex behaviors like instantaneous camouflage, and other unique traits.

This video was taken with polychromatic polarization microscope, as described in the Scientific Reports paper “Polychromatic Polarization Microscope: Bringing Colors to a Colorless World” by Shribak. The color is generated by interaction of white polarized light with the squid’s transparent soft tissue. The tissue works as a living tunable spectral filter, and the transmission band depends on the molecular orientation. When the young squid is moving, the tissue orientation changes, and its color shifts accordingly.

Using a supercomputer to simulate the movement of atoms in a ribosome, researchers looked into the core of this protein-making nanomachine and took snapshots. The picture shows an amino acid (green) being delivered by transfer RNA (yellow) into a corridor (purple) in the ribosome. In the corridor, a series of chemical reactions will string together amino acids to make a protein. The research project, which tracked the movement of more than 2.6 million atoms, was the largest computer simulation of a biological structure to date. The results shed light on the manufacturing of proteins and could aid the search for new antibiotics, which typically work by disabling the ribosomes of bacteria.

A light microscope image of a cell from the endosperm of an African globe lily (Scadoxus katherinae). This is one frame of a time-lapse sequence that shows cell division in action. The lily is considered a good organism for studying cell division because its chromosomes are much thicker and easier to see than human ones. Staining shows microtubules in red and chromosomes in blue. Here, condensed chromosomes are clearly visible and have lined up in the middle of the dividing cell.

Related to images 1010, 1011, 1012, 1013, 1014, 1015, 1016, 1018, 1019, and 1021.

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. Typical circadian rhythms lead to high energy during the middle of the day (10 a.m. to 1 p.m.) and an afternoon slump. At night, circadian rhythms cause the hormone melatonin to rise, making a person sleepy.

Learn more in NIGMS’ circadian rhythms featured topics page.

See 6612 for the Spanish version of this infographic.

3D reconstructions of two stages in the assembly of the bacterial ribosome created from time-resolved cryo-electron microscopy images. Ribosomes translate genetic instructions into proteins.

Mitochondria are the powerhouses of the cells, generating the energy the cells need to do their tasks and to stay alive. Researchers have studied mitochondria for some time because when these cell organelles don't work as well as they should, several diseases develop. In this photograph of cow cells taken with a microscope, the mitochondria were stained in bright yellow to visualize them in the cell. The large blue dots are the cell nuclei and the gray web is the cytoskeleton of the cells.

Ecteinascidin 743 (ET-743, brand name Yondelis), was discovered and isolated from a sea squirt, Ecteinascidia turbinata, by NIGMS grantee Kenneth Rinehart at the University of Illinois. It was synthesized by NIGMS grantees E.J. Corey and later by Samuel Danishefsky. Multiple versions of this structure are available as entries 2790-2797.

A crawling cell with DNA shown in blue and actin filaments, which are a major component of the cytoskeleton, visible in pink. Actin filaments help enable cells to crawl. This image was captured using structured illumination microscopy.

Neurons (green) and glial cells from isolated dorsal root ganglia express COX-2 (red) after exposure to an inflammatory stimulus (cell nuclei are blue). Lawrence Marnett and colleagues have demonstrated that certain drugs selectively block COX-2 metabolism of endocannabinoids -- naturally occurring analgesic molecules -- in stimulated dorsal root ganglia. Featured in the October 20, 2011 issue of Biomedical Beat.

Multiple actin filaments (magenta) are organized around a dynamin helical polymer (rainbow colored) in this model derived from cryo-electron tomography. By bundling actin, dynamin increases the strength of a cell’s skeleton and plays a role in cell-cell fusion, a process involved in conception, development, and regeneration.

The worm Caenorhabditis elegans is a popular laboratory animal because its small size and fairly simple body make it easy to study. Scientists use this small worm to answer many research questions in developmental biology, neurobiology, and genetics. This image, which was taken with transmission electron microscopy (TEM), shows a cross-section through C. elegans, revealing various internal structures.

The image is from a figure in an article published in the journal eLife. There is an annotated version of this graphic at 5760.

Cilia (cilium in singular) are complex molecular machines found on many of our cells. One component of cilia is the doublet microtubule, a major part of cilia’s skeletons that give them support and shape. This animated video illustrates the structure of doublet microtubules, which contain 451 protein chains that were mapped using cryo-electron microscopy. Image can be found here 6548.

By attaching fluorescent proteins to the genetic circuit responsible for B. subtilis's stress response, researchers can observe the cells' pulses as green flashes. This video shows flashing cells as they multiply over the course of more than 12 hours. In response to a stressful environment like one lacking food, B. subtilis activates a large set of genes that help it respond to the hardship. Instead of leaving those genes on as previously thought, researchers discovered that the bacteria flip the genes on and off, increasing the frequency of these pulses with increasing stress. See entry 3253 for a related still image.

The interior of a regenerating lizard tail 14 days after the original tail was amputated. Cell nuclei (blue), proliferating cells (green), cartilage (red), and muscle (white) have been visualized with immunofluorescence staining.

Map of microtubule growth rates. Rates are color coded. This is an example of NIH-supported research on single-cell analysis. Related to 2798 , 2799, 2801, 2802 and 2803.

A crystal of hen egg lysozyme protein created for X-ray crystallography, which can reveal detailed, three-dimensional protein structures.

Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. Circadian rhythms are influenced by light and regulated by the brain’s suprachiasmatic nucleus (SCN), sometimes referred to as a master clock. Learn more in NIGMS’ circadian rhythms fact sheet. See 6614 for the Spanish version of this infographic.

This image shows the uncontrolled growth of cells in squamous cell carcinoma, the second most common form of skin cancer. If caught early, squamous cell carcinoma is usually not life-threatening.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

Some children are born with a mutation in a regulatory site on this enzyme that causes them to over-secrete insulin when they consume protein. We found that a compound from green tea (shown in the stick figure and by the yellow spheres on the enzyme) is able to block this hyperactivity when given to animals with this disorder.

Bioengineers were able to coax bacteria to blink in unison on microfluidic chips. This image shows a small chip with about 500 blinking bacterial colonies or biopixels. Related to images 3265 and 3268. From a UC San Diego news release, "Researchers create living 'neon signs' composed of millions of glowing bacteria."

The photo shows a confocal microscopy image of perineuronal nets (PNNs), which are specialized extracellular matrix (ECM) structures in the brain. The PNN surrounds some nerve cells in brain regions including the cortex, hippocampus and thalamus. Researchers study the PNN to investigate their involvement stabilizing the extracellular environment and forming nets around nerve cells and synapses in the brain. Abnormalities in the PNNs have been linked to a variety of disorders, including epilepsy and schizophrenia, and they limit a process called neural plasticity in which new nerve connections are formed. To visualize the PNNs, researchers labeled them with Wisteria floribunda agglutinin (WFA)-fluorescein. Related to image 3741.

After multiplying inside a host cell, the stringlike Ebola virus is emerging to infect more cells. Ebola is a rare, often fatal disease that occurs primarily in tropical regions of sub-Saharan Africa. The virus is believed to spread to humans through contact with wild animals, especially fruit bats. It can be transmitted between one person and another through bodily fluids.

This image was part of the Life: Magnified exhibit that ran from June 3, 2014, to January 21, 2015, at Dulles International Airport.

A blue laser beam turns on a protein that helps this human cancer cell move. Responding to the stimulus, the protein, called Rac1, first creates ruffles at the edge of the cell. Then it stretches the cell forward, following the light like a horse trotting after a carrot on a stick. This new light-based approach can turn Rac1 (and potentially many other proteins) on and off at exact times and places in living cells. By manipulating a protein that controls movement, the technique also offers a new tool to study embryonic development, nerve regeneration and cancer.

Drugs enter different layers of skin via intramuscular, subcutaneous, or transdermal delivery methods. See image 2532 for a labeled version of this illustration. Featured in Medicines By Design.

The green spots in this image are clumps of protein inside yeast cells that are deficient in both zinc and a protein called Tsa1 that prevents clumping. Protein clumping plays a role in many diseases, including Parkinson's and Alzheimer's, where proteins clump together in the brain. Zinc deficiency within a cell can cause proteins to mis-fold and eventually clump together. Normally, in yeast, Tsa1 codes for so-called "chaperone proteins" which help proteins in stressed cells, such as those with a zinc deficiency, fold correctly. The research behind this image was published in 2013 in the Journal of Biological Chemistry.

A zebrafish embryo. The blue areas are cell bodies, the green lines are blood vessels, and the red glow is blood. This image was created by stitching together five individual images captured with a hyperspectral multipoint confocal fluorescence microscope that was developed at the Eliceiri Lab.

This illustration shows, in simplified terms, how the CRISPR-Cas9 system can be used as a gene-editing tool.

Frame 1 shows the two components of the CRISPR system: a strong cutting device (an enzyme called Cas9 that can cut through a double strand of DNA), and a finely tuned targeting device (a small strand of RNA programmed to look for a specific DNA sequence).

In frame 2, the CRISPR machine locates the target DNA sequence once inserted into a cell.

In frame 3, the Cas9 enzyme cuts both strands of the DNA.

Frame 4 shows a repaired DNA strand with new genetic material that researchers can introduce, which the cell automatically incorporates into the gap when it repairs the broken DNA.

For an explanation and overview of the CRISPR-Cas9 system, see the iBiology video.

Download the individual frames: Frame 1, Frame 2, Frame 3, and Frame 4.

This image integrates the thousands of known molecular and genetic interactions happening inside our bodies using a computer program called Cytoscape. Images like this are known as network wiring diagrams, but Cytoscape creator Trey Ideker somewhat jokingly calls them "hairballs" because they can be so complicated, intricate and hard to tease apart. Cytoscape comes with tools to help scientists study specific interactions, such as differences between species or between sick and diseased cells. Related to 2737.

How far and fast an infectious disease spreads across a community depends on many factors, including transportation. These U.S. maps, developed as part of an international study to simulate and analyze disease spread, chart daily commuting patterns. They show where commuters live (top) and where they travel for work (bottom). Green represents the fewest number of people whereas orange, brown, and white depict the most. Such information enables researchers and policymakers to visualize how an outbreak in one area can spread quickly across a geographic region.

The extracellular matrix (ECM) is most prevalent in connective tissues but also is present between the stems (axons) of nerve cells, as shown here. Blue-colored nerve cell axons are surrounded by brown-colored, myelin-supplying Schwann cells, which act like insulation around an electrical wire to help speed the transmission of electric nerve impulses down the axon. The ECM is pale pink. The tiny brown spots within it are the collagen fibers that are part of the ECM.

A cell in prometaphase during mitosis: The nuclear membrane breaks apart, and the spindle starts to interact with the chromosomes. Mitosis is responsible for growth and development, as well as for replacing injured or worn out cells throughout the body. For simplicity, mitosis is illustrated here with only six chromosomes.

Leptospira, shown here in green, is a type (genus) of elongated, spiral-shaped bacteria. Infection can cause Weil's disease, a kind of jaundice, in humans.

This is a tomographic reconstruction of a mitochondrion from an insect flight muscle. Mitochondria are cellular compartments that are best known as the powerhouses that convert energy from the food into energy that runs a range of biological processes. Nearly all our cells have mitochondria.

Researchers used cryo-electron tomography (cryo-ET) to capture images of a rat pancreas cell that were then compiled and color-coded to produce a 3D reconstruction. Visible features include the folded sacs of the Golgi apparatus (copper), transport vesicles (medium-sized dark-blue circles), microtubules (neon-green rods), a mitochondria membrane (pink), ribosomes (small pale-yellow circles), endoplasmic reticulum (aqua), and lysosomes (large yellowish-green circles). See 6606 for a still image from the video.

This video shows an instance of abnormal mitosis where chromosomes are late to align. The video demonstrates the spindle checkpoint in action: just one unaligned chromosome can delay anaphase and the completion of mitosis. The cells shown are S3 tissue cultured cells from Xenopus laevis, African clawed frog.

An RNA molecule dynamically refolds itself as it is being synthesized. When the RNA is short, it ties itself into a “knot” (dark purple). For this domain to slip its knot, about 5 seconds into the video, another newly forming region (fuchsia) wiggles down to gain a “toehold.” About 9 seconds in, the temporarily knotted domain untangles and unwinds. Finally, at about 23 seconds, the strand starts to be reconfigured into the shape it needs to do its job in the cell.

The research organism Arabidopsis thaliana forms a large molecular machine called a resistosome to fight off infections. This illustration shows the top and side views of the fully-formed resistosome assembly (PDB entry 6J5T), composed of different proteins including one the plant uses as a decoy, PBL2 (dark blue), that gets uridylylated to begin the process of building the resistosome (uridylyl groups in magenta). Other proteins include RSK1 (turquoise) and ZAR1 (green) subunits. The ends of the ZAR1 subunits (yellow) form a funnel-like protrusion on one side of the assembly (seen in the side view). The funnel can carry out the critical protective function of the resistosome by inserting itself into the cell membrane to form a pore, which leads to a localized programmed cell death. The death of the infected cell helps protect the rest of the plant.