The word phase means to change a part of a development
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Unlike typical mammalian red blood cells, those from amphibians, such as frogs, contain a DNA-bearing nucleus that is visible in the center of the cell. The circulatory system of amphibians is rather unusual, their hearts having three chambers, two atria, and a single ventricle.
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The design of the amphibian circulatory system is curious because blood accumulates oxygen in the lungs and is then returned to the heart before being pumped into the rest of the circulatory system. Therefore, a mixing between oxygenated and deoxygenated blood occurs as blood returning to the heart from the lungs is mixed with incoming blood from the body. Frogs handle this situation by having a very slow metabolism and by absorbing some oxygen through their skin. In addition, the ventricle does have some directional control over the distribution of the blood.
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The presence of a nucleus in amphibian red blood cells allows researchers easy access to large quantities of amphibian DNA. Frog blood has both a solid and a liquid portion. The liquid plasma carries solid elements such as red and white blood cells. Blood can be collected from frogs and the red blood cells isolated by centrifugation. After removal of the residual plasma, purified cells can be treated with specific enzymes and detergents to digest the cellular envelope and release DNA from its protein complex. The DNA is then useful for scientific studies and experiments.
Featured in: Phase Contrast
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Restoration of native plants and habitats on campuses can provide ecosystem services such as slowing storm water runoff and filtering pollution-c.
A(n) ___ is a group of terrestrial communities that covers a large area and is characterized by certain soil and ____ conditions and particular types of plants and animals
A mineral is a naturally occurring, inorganic compound with a unique chemical structure and physical properties. A rock is a solid, stony mass composed of a combination of minerals or other organic compounds. For example, quartz and feldspars are minerals, but when formed together, they make a rock, granite.
