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The cell nucleus (from Latin nucleus or nuculeus 'kernel, seed'; pl.: nuclei) is a membrane-bound organelle found in eukaryotic cells.Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, have no nuclei, and a few others including osteoclasts have many.
The larger organelles, such as the nucleus and vacuoles, are easily visible with the light microscope. They were among the first biological discoveries made after the invention of the microscope . Not all eukaryotic cells have each of the organelles listed below.
Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope. Cells emerged on Earth about 4 billion years ago.
A transmission electron microscope from 2002 An image of an ant in a scanning electron microscope. An electron microscope is a microscope that uses a beam of electrons as a source of illumination. They use electron optics that are analogous to the glass lenses of an optical light microscope to control the electron beam, for instance focusing ...
By Keith Morrison Taking the phrase of "putting it under the microscope" quite literally, the Nikon Small World contest recently announced its winners for 2014. Now in its 40th year, the contest ...
The vault or vault cytoplasmic ribonucleoprotein is a eukaryotic organelle (a structure in the cells of multicellular organisms) whose function is not yet fully understood. . Discovered and isolated by Nancy Kedersha and Leonard Rome in 1986, [2] vaults are cytoplasmic structures (outside the nucleus) which, when negative-stained and viewed under an electron microscope, resemble the arches of ...
A reaction occurs between the antigen and antibody, causing this label to become visible under the microscope. Scanning electron microscopy is a viable option if the antigen is on the surface of the cell, but transmission electron microscopy may be needed to see the label if the antigen is within the cell. [2]
Electron micrograph of endosomes in human HeLa cells. Early endosomes (E - labeled for EGFR, 5 minutes after internalisation, and transferrin), late endosomes/MVBs (M) and lysosomes (L) are visible. Bar, 500 nm. Endosomes are a collection of intracellular sorting organelles in eukaryotic cells.