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A nucleus typically contains between one and ten compact structures called Cajal bodies or coiled bodies (CB), whose diameter measures between 0.2 μm and 2.0 μm depending on the cell type and species. [35] When seen under an electron microscope, they resemble balls of tangled thread [36] and are dense foci of distribution for the protein ...
Nucleus (pl.: nuclei) is a Latin word for the seed inside a fruit. It most often refers to: Atomic nucleus, the very dense central region of an atom; Cell nucleus, a central organelle of a eukaryotic cell, containing most of the cell's DNA; Nucleus may also refer to:
There are many differences between the types of nuclei. This feature is observed in protozoan ciliates , like Tetrahymena , and some foraminifera . Ciliates contain two nucleus types: a macronucleus that is primarily used to control metabolism , and a micronucleus which performs reproductive functions and generates the macronucleus.
A model of an atomic nucleus showing it as a compact bundle of protons (red) and neutrons (blue), the two types of nucleons.In this diagram, protons and neutrons look like little balls stuck together, but an actual nucleus (as understood by modern nuclear physics) cannot be explained like this, but only by using quantum mechanics.
This remarkable difference of nuclear binding energy between neighbouring nuclei, especially of odd-A isobars, has important consequences: unstable isotopes with a nonoptimal number of neutrons or protons decay by beta decay (including positron decay), electron capture or more exotic means, such as spontaneous fission and cluster decay.
If there is a difference, it is too small to measure in all experiments to date.) In particular, antinucleons can bind into an "antinucleus". So far, scientists have created antideuterium [4] [5] and antihelium-3 [6] nuclei.
The net binding energy of a nucleus is that of the nuclear attraction, minus the disruptive energy of the electric force. As nuclei get heavier than helium, their net binding energy per nucleon (deduced from the difference in mass between the nucleus and the sum of masses of component nucleons) grows more and more slowly, reaching its peak at iron.
A nuclear isomer is a metastable state of an atomic nucleus, in which one or more nucleons (protons or neutrons) occupy excited state levels (higher energy levels). ). "Metastable" describes nuclei whose excited states have half-lives 100 to 1000 times longer than the half-lives of the excited nuclear states that decay with a "prompt" half life (ordinarily on the order of 10