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from article Barracuda
Great barracuda (Sphyraena barracuda). (Photo copyright © John E. Randall)
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from article Cardiovascular system
Computerized artwork of the human cardiovascular system, including the heart, lungs, and major arteries and veins. (Credit: Science Photo Library RF/Getty Images)
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from article Cardiovascular system
Diagram of the heart and major vessels of a fetus just before birth. Small arrows within the liver indicate alternative blood routes by way of hepatic sinusoids. (Credit: Based on an original drawing by B. M. Patten; copyright © McGraw-Hill…
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from article Cardiovascular system
Single type of circulatory system. (Credit: Based on an original drawing by C. K. Weichert; copyright © McGraw-Hill Education)
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from article Cardiovascular system
Double type of circulatory system in a vertebrate having a four-chambered heart (ventral view). (Credit: Based on an original drawing by C. K. Weichert; copyright © McGraw-Hill Education)
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from article Cardiovascular system
Illustration of the human cardiovascular system, which involves pulmonary circulation and systemic circulation. Red vessels transport oxygenated blood; blue vessels transport deoxygenated blood; and purple vessels are involved in gas exchange.…
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from article Hematologic disorders
Myelophthisic anemia results from a space-occupying lesion in the bone marrow, which hinders hematopoiesis (the process by which the cellular elements of the blood are formed). In this photomicrograph, the bone marrow space is expanded, and the…
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from article Hematologic disorders
Scanning electron micrograph of (top) an elongated, flattened sickle cell and (bottom) a normal red blood cell. (Credit: Callista Images/Image Source/Getty Images)
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from article Hematologic disorders
Colored scanning electron micrograph of round leukocytes from a patient with leukemia. (Credit: Steve Gschmeissner/Science Photo Library)
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from article Allometry
Allometric lines for the mass of some organs across mammal species. (These are best-fit lines: individual species may lie above or below them.) Note that the skeleton is disproportionately heavy in large species (positive allometry), whereas the…
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from article Allometry
Three different types of allometry. Each curve shows the growth allometry of organ size in a different species. The adults of each species show static intraspecific allometry. The circles indicate a particular stage of the life history (for example,…
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from article Goat production
Domesticated goats (Capra hircus) raised for meat goat production. (Photo by Susan Boyer, Agricultural Research Service, U.S. Department of Agriculture)
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from article Goat production
Close-up view of a Saanen goat. (Photo by Milan Kořínek)
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from article Goat production
Mechanical (automatic) milking of a purebred Nigerian Dwarf dairy goat on an elevated stand. (Photo courtesy of Lesa Wilke, Bramblestone Farm, Ohio; www.bramblestonefarm.com)
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from article Xenophyophorida
Xenophyophorids. (a) Stannoma dendroides. (b) Stannophyllum zonarium. (c) Psammetta erythrocytomorpha, section showing interlacing tubules and dark inclusions of uncertain nature.
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from article Fungi
Porcini mushrooms (Boletus edulis) are members of the Basidiomycota division of Fungi. (Credit: Digoarpi/Shutterstock)
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from article Fungi
Spore types (upper illustrations) and structures of parent mycelia (lower illustrations) in fungi.
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from article Fungi
Sporangia of saprophytic Rhizopus. (Credit: Richard Gross; copyright © McGraw-Hill Education)
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from article Fungi
Sexual mechanisms in fungi: (a) gametic copulation; (b) gametangial copulation; (c) gamete-gametangial copulation; and (d) somatic copulation.
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from article Fungi
Colorized scanning electron micrograph of brewer's yeast cells (Saccharomyces cerevisiae). This fungus consists of single vegetative cells, and small daughter cells can be seen budding off from the larger cells. Brewer's yeast is used in the…
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from article Apple
Empire apple (Malus pumila). (Credit: Peggy Greb/Agricultural Research Service, United States Department of Agriculture)
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from article Apple
Apple trees in an orchard in late autumn. (Credit: Sandrine Bouvier/Alamy)
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from article Pericycle
Pericycles. (a) Part of transection of root Actaea alba, including xylem and phloem. Pericycle thin-walled and one cell in radial dimension. (b) Part of transection of root of Smilax herbacea, including phloem. Pericycle thick-walled and four or…
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from article Pericycle
Transection of central part of sugarbeet. (After K. Esau, Hilgardia, 9(8), 1935)
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from article Medical bacteriology
Microscopic view of bacterial pneumonia, which is a type of pneumonia caused by bacterial infection. (Credit: Stocktrek Images/Corbis)
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from article Medical bacteriology
Bacteria culture growth on agar medium in a petri dish. (Credit: Sompraaong0042/Shutterstock)
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from article Genetically modified organism (GMO)
Transgenic zebrafish cells. Green fluorescent protein (GFP) is a fluorescent protein first discovered in the jellyfish Aequorea victoria. GFP is commonly used as a reporter of gene expression in other species. Here, GFP is expressed by zebrafish…
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from article Genetically modified organism (GMO)
Genome editing technologies. In particular, targeted nucleases are a powerful tool for precise genome editing in GMOs. Among these tools are (a) transcription activator-like effector nucleases (TALENs), (b) zinc-finger proteins (ZFPs), (c) homing…
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from article Wood anatomy
Annual tree rings are distinct features of wood anatomy. The combined concentric bands of light and dark areas can help investigators to determine the age of a tree. (Credit: DrimaFilm/Shutterstock)
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from article Wood anatomy
Light micrograph of a section through the stem of a lime tree (genus Tilia). The pith is at the center and is surrounded by a layer of wood (xylem). A thin cambium separates this from the phloem. An outer layer of collenchyma is enclosed by the…
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from article Wood anatomy
Structure of a typical hardwood. (Credit: U.S. Department of Agriculture)
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from article Wood anatomy
Structure of a typical softwood. (Credit: U.S. Department of Agriculture)
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from article Channelrhodopsin
Three-dimensional (3D) protein crystal structure of channelrhodopsin variant C1C2. (Image courtesy of Protein Data Bank 3UG9, Molecular Modeling Database 96737)
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from article Melatonin
Chemical structure of melatonin (C13H16N2O2).
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from article Plague
Plague ecology in the United States. The left panel shows how plague occurs in nature among rodents. The right panel shows how plague is spread from rodents to humans and domestic animals. (Credit: Centers for Disease Control and Prevention)
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from article Sloan Digital Sky Survey
Sloan Digital Sky Survey (SDSS) 2.5-m (98-in.) telescope at Apache Point Observatory, New Mexico. The secondary mirror is visible in the center of the aperture. The square structure surrounding the primary and secondary mirrors shelters them from…
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from article Sloan Digital Sky Survey
Spectrum of a galaxy (image inset) receding at around 6000 km s−1 (3700 mi s−1), or about 2% of the speed of light. The vertical line shows the wavelength at which one expects to observe the emission line Hα for an object at rest (656.3 nm). The…
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from article Sloan Digital Sky Survey
Distribution of galaxies within 4° of the celestial equator from the SDSS. In this polar plot, the radius indicates the distance from the Milky Way, and the angle is the right ascension. The diameter shown is 8 × 109 light-years. Blank areas have…
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from article Sloan Digital Sky Survey
Map of stars in the SDSS. Grayscale signifies density of stars on the sky. Several streams of stars are noticeable. Areas in background are those unobserved by the survey. (Courtesy of Vasily Belokurov; Sloan Digital Sky Survey)
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from article Sloan Digital Sky Survey
Image of Canes Venatici I, a recently discovered satellite of the Milky Way Galaxy. (Photo courtesy of Vasily Belokurov; Sloan Digital Sky Survey)
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from article Sloan Digital Sky Survey
Hubble sequence of galaxies, as observed by the SDSS. Elliptical galaxies (types marked E0 and E6) are old, spheroidal, and very massive. Spiral galaxies are on average less massive. While some spiral galaxies (S0 and Sa) tend to have very little…
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from article Nursing
Nursing provides physical and emotional care to ailing individuals. (Credit: Fuse/Getty Images)
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from article Musk-ox
Musk-ox (Ovibos moschatus). (Credit: Brent Huffman/Ultimate Ungulate Images)
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from article Binary and multiple asteroids
Asteroid 121 Hermione and its moonlet companion observed with the adaptive optics system mounted on the European Southern Observatory's Very Large Telescope [consisting of four 8.2-m (25-ft) telescopes] at six different times. The satellite revolves…
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from article Arales
Anthurium andraeanum (flamingo lily). (Photo courtesy of Forest and Kim Starr)
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from article Potato
Potato (Solanum tuberosum), also known as the Irish potato. (Credit: Peggy Greb/Agricultural Research Service, U.S. Department of Agriculture)
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from article Potato
Diagram of a potato plant. (Credit: Potato Association of America)
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from article Potato
Potato tubers infected by late blight (caused by Phytophthora infestans). (Credit: G. D. Franc)
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from article Phospholipases
Sites at which different phospholipases cleave the typical phospholipid phosphatidylcholine. F1 and F2 are long-chain fatty acids esterified at positions 1 and 2 of the glycerol backbone, respectively.
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from article Phospholipases
Mechanisms by which activated receptors coupled to phospholipase C (PLC) through heterotrimeric G proteins produce their physiological responses. Terms: PIP2, phosphatidylinositol bisphosphate; DAG, diacylglycerol; PKC, protein kinase C; IP3,…
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from article Persian melon
Persian melon (Cucumis melo). (Photo by Mehrdad Aref-Adib)
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from article Marten
American marten (also known as the American pine marten; Martes americana). (Photo by Gerald and Buff Corsi; copyright © California Academy of Sciences)
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from article Human ecology
Shacks and garbage along a dirty river in a slum in Manila, Philippines. Human ecology encompasses how individual people and their communities interact with their particular environment. In many cases, though, humans have created polluted…
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from article Human ecology
Burning of a tropical rainforest in Brazil in order to clear land for animal grazing. (Credit: Barry Barker; copyright © McGraw Hill)
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from article Saturn
Saturn viewed on April 25, 2016 by the Cassini orbiter as the planet neared its northern hemisphere's summer solstice. (Credit: NASA/JPL-Caltech/Space Science Institute)
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from article Saturn
Saturn viewed from the Cassini orbiter. The soft velvety appearance of the low-contrast banded structure is due to scattering by the haze layer above the planet's cloud deck. The image has been rotated so that north is up. The Sun illuminates Saturn…
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from article Saturn
Presentations of Saturn's ring system over the course of a Saturnian year.
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from article Saturn
Images from the Cassini spacecraft show the life cycle of Saturn's great northern storm beginning on December 5, 2010, when a small white cloud appeared at latitude 33°N. In these views, the Cassini spacecraft was in the ring plane, and the ring…
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from article Saturn
A natural color view of Saturn's rings from the Cassini Orbiter taken on August 22, 2009, at a distance of 2.05 million km (1.27 million mi) from Saturn. (Credit: NASA/JPL/Space Science Institute)
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from article Saturn
Structure of Saturn's rings observed by two different approaches. The upper half of the image is a natural-color mosaic of images by the Cassini narrow-angle camera. Such images have information about how ring structure differs both with distance…
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from article Saturn
Saturn's F ring viewed from the Cassini orbiter. Features resembling drapes and kinks are visible, and several distinct ringlets are present, in addition to the bright knotted core of the ring. The structure in the ring and its strands has been…
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from article Saturn
Titan superimposed in front of Saturn, captured by the Cassini spacecraft. (Credit: NASA/JPL-Caltech/Space Science Institute)
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from article Saturn
The satellite Phoebe taken during Cassini's flyby on June 11, 2004. The image shows evidence for the theory that Phoebe is an ice-rich body coated with a thin layer of dark material. (Credit: NASA/JPL/Space Science Institute)
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from article DNA methylation
In humans and other mammals, DNA methylation involves the addition of a methyl group to a cytosine ring, forming methylcytosine. The methylation is carried out by a DNA methyltransferase (DNMT). (Copyright © McGraw-Hill Education)
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from article DNA methylation
Transcriptional silencing via DNA methylation. The methylated configuration blocks proteins that activate gene transcription, preventing them from acting as gene activators. (Copyright © McGraw-Hill Education)
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from article Microtechnique
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from article Microtechnique
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from article Microtechnique
Materials and method for applying cover slip to balsam wholemount. (a) Correct way; notice that the cover slip is held vertically centered over the drop of balsam. (b) Wrong way; this method draws the object to one side. (After P. Gray, Handbook of…
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from article Microtechnique
Making a smear preparation. (a) Place the drop about 1 in. (2.5 cm) from end of slide. (b) Apply a second slide just in front of the drop. (c) Push slide smoothly forward to spread the smear. (After P. Gray, Handbook of Basic Microtechnique, 3d ed.,…
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from article Microtechnique
Rotary microtome produced by the American Optical Co. (From P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)
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from article Microtechnique
Method of mounting the wax block on the block holder. (After P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)
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from article Microtechnique
Basic steps in cutting and mounting paraffin ribbons prior to staining. (a) Starting the ribbon. (b) Cutting the ribbon in lengths. (c) Mounting the dry ribbon. (d) Flooding the ribbons. (e) Warming the flooded ribbons to flatten them. (After P.…
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from article Microtechnique
Coplin jars for starting a slide through the reagent series. (After P. Gray, Handbook of Basic Microtechnique, 3d ed., McGraw-Hill, 1964)
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from article Capricornus
Modern boundaries of the constellation Capricornus, the Sea Goat. The celestial equator is 0° of declination, which corresponds to celestial latitude. Right ascension corresponds to celestial longitude, with each hour of right ascension representing…
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from article Bioorganic chemistry
Vancomycin and an analog that is active against vancomycin-resistant bacteria.
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from article Bioorganic chemistry
Foldamers that mimic proteins.
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from article Bioorganic chemistry
The rate of this intramolecular lactonization, relative to that of intermolecular esterification, mimics the rate increase caused by an enzyme's binding and orienting substrates for a bimolecular reaction.
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from article Bioorganic chemistry
Intramolecular models of enzymatic general acid and general base catalysis. (a) Intramolecular general acid catalysis causes this acetal to hydrolyze at pH 7 more than 107 times faster than the corresponding acetal without the carboxylic acid group.…
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from article Bioorganic chemistry
An antibody raised against the phosphonate analog of a tetrahedral intermediate catalyzes the hydrolysis of cocaine to ecgonine methyl ester.
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from article Bioorganic chemistry
A functionalized cyclodextrin mimics the enzyme RNase by catalyzing the regioselective hydrolysis of a model phosphodiester.
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from article Bioorganic chemistry
Enzyme-catalyzed reactions that have been commercialized as industrial processes.
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from article Bioorganic chemistry
Mechanism of DNA scission by calicheamicin. Reductive or nucleophilic cleavage of the trisulfide triggers conjugate (Michael) addition to the enone, rehybridization of the bridgehead carbon, and Bergman cyclization of the enediyne, generating a…
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from article Type 1 diabetes
One characteristic feature of type 1 diabetes is glomerulosclerosis (Kimmelstiel-Wilson lesion), which involves the scarring or hardening of the glomeruli (blood vessels) in the kidneys. (Copyright © McGraw Hill)
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from article Type 1 diabetes
Stages in the development of type 1 diabetes. (Credit: Type 1 Diabetes TrialNet)
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from article Parathyroid gland
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from article Parathyroid gland
Common positions of human parathyroid glands on the posterior aspect of the thyroid. (After W. H. Hollinshead, Anatomy of the endocrine glands, Surg. Clin. N. Amer., 32(4):1115–1140, 1952)
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from article Parathyroid gland
Section of human parathyroid gland, demonstrating the two main parenchymal cell types. Zenker-formal fixation, Mallory-azan stain. (After D. Bloom and D. W. Fawcett, A Textbook of Histology, 9th ed., Saunders, 1968)
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from article Parathyroid gland
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from article Tanaidacea
Leviapseudes bipartitus. [K. Larsen, Deep-Sea Tanaidacea (Peracarida) from the Gulf of Mexico, Brill, Leiden, 2005]
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from article Tanaidacea
Typhlotanais ohtsukae: (top) female; (bottom) male. [K. Larsen and M. Shimomura, Tanaidacea (Crustacea: Peracarida) from Japan: II. Tanaidomorpha from the East China Sea, the West Pacific Ocean and the Nansei Islands, Zootaxa, 1464:1–43, 2007]
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from article Polypodiales
Licorice fern (Polypodium glycyrrhiza), a member of the order Polypodiales, in Olympic National Forest, Washington. (Photo courtesy of the U.S. Department of Agriculture, Forest Service)
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from article Polypodiales
Christmas fern (Polystichum acrostichoides). (Photo by James H. Miller, U.S. Department of Agriculture, Forest Service)
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from article Polypodiales
The sensitive fern (Onoclea sensibilis), a representative of the Polypodiales. (After W. W. Robbins, T. E. Weier, and C. R. Stocking, Botany: An Introduction to Plant Science, 3d ed., Wiley, New York, 1964)
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from article Polypodiales
Types of steles in the Polypodiales: (a) Protostele. (b) Amphiphloic siphonostele. (c) Ectophloic siphonostele. (d) Dictyostele with central pith surrounded by xylem and phloem in the form of discrete vascular bundles; bands of parenchyma cells…
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from article Polypodiales
Life history of a fern: (1) the fern plant, or sporophyte, bearing sori, or clusters of sporangia, on its leaves; (2) a sporangium; (3) a tetrad of young spores; (4) the four mature spores that have come from the tetrad shown in part 3; (5) a spore…
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from article Polypodiales
Diagram of section through a fern leaf, showing details of a sorus. (After W. W. Robbins, T. E. Weier, and C. R. Stocking, Botany: An Introduction to Plant Science, 3d ed., Wiley, New York, 1964)
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from article Polypodiales
Eastern marsh fern (Thelypteris palustris): sori on the pinnules of a fertile frond. (Photo by Rob Routledge, Sault College, Sault Ste. Marie, Ontario, Canada)
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from article Polypodiales
Diagram of a fern prothallium. (After W. W. Robbins, T. E. Weier, and C. R. Stocking, Botany: An Introduction to Plant Science, 3d ed., Wiley, New York, 1964)
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from article Yeast
Colorized scanning electron micrograph (SEM) of Schizosaccharomyces pombe yeast. This single-celled fungus is studied widely as a model organism for eukaryotic cell division. It is a rod-shaped yeast that grows by elongation at its ends, and it…
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from article Yeast
Cell shapes of yeasts are extremely varied: (a) rectangular; (b) pear-shaped; (c) apiculate; (d) ogival; (e) spherical; (f) globose; (g) ellipsoidal (oval); (h) elongate; (i) tetrahedral. (Copyright © McGraw Hill)
