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Little was known about the function of the nucleolus until 1964, when a study [10] of nucleoli by John Gurdon and Donald Brown in the African clawed frog Xenopus laevis generated increased interest in its function and detailed structure. They found that 25% of the frog eggs had no nucleolus, and that such eggs were not capable of life.
The organelles and other structures within the cytoplasm and nucleoplasm are organized by protein filaments within their respective compartments. The cytoplasm contains the cytoskeleton, a network of protein filaments found in all cells, while the nucleoplasm is believed to contain the nuclear matrix, a hypothetically analogous network of ...
[4] [5] [6] It is found within the nucleolus that binds p53. [7] Nucleostemin regulates the cell cycle and affects cell differentiation, decreasing in amount as this differentiation progresses. [7] It is a marker for many stem cells and cancer cells. [8]
Nucleolus organizer regions (NORs) are chromosomal regions crucial for the formation of the nucleolus. In humans, the NORs are located on the short arms of the acrocentric chromosomes 13, 14, 15, 21 and 22, the genes RNR1, RNR2, RNR3, RNR4, and RNR5 respectively. [1] These regions code for 5.8S, 18S, and 28S ribosomal RNA. [1]
In terms of protein synthesis, the necessary organelles are relatively near one another. The nucleolus within the nuclear envelope is the location of ribosome synthesis. The destination of synthesized ribosomes for protein translation is rough endoplasmic reticulum (rough ER), which is connected to and shares the same membrane with the nucleus.
In mammals, the nucleolus of the oocyte is derived solely from maternal cells. [22] The nucleolus, a structure found within the nucleus, is the location where rRNA is transcribed and assembled into ribosomes. While the nucleolus is dense and inactive in a mature oocyte, it is required for proper development of the embryo. [22]
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The cytoplasm describes all the material within a eukaryotic or prokaryotic cell, enclosed by the cell membrane, except for the organelles. [1] The material inside the nucleus of a eukaryotic cell and contained within the nuclear membrane is termed the nucleoplasm.