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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 nuclear envelope has many nuclear pores that allow materials to move between the cytosol and the nucleus. [4] Intermediate filament proteins called lamins form a structure called the nuclear lamina on the inner aspect of the inner nuclear membrane and give structural support to the nucleus. [4]
Shoot apical meristems are the source of all above-ground organs, such as leaves and flowers. Cells at the shoot apical meristem summit serve as stem cells to the surrounding peripheral region, where they proliferate rapidly and are incorporated into differentiating leaf or flower primordia.
With microscopes during this time having a low magnification, Hooke was unable to see that there were other internal components to the cells he was observing. Therefore, he did not think the "cellulae" were alive. His cell observations gave no indication of the nucleus and other organelles found in most living cells.
Each human cell contains around two metres of DNA, which must be tightly folded to fit inside the cell nucleus. However, in order for the cell to function, proteins must be able to access the sequence information contained within the DNA, in spite of its tightly-packed nature. Hence, the cell has a number of mechanisms in place to control how ...
An endosperm is formed after the two sperm nuclei inside a pollen grain reach the interior of a female gametophyte or megagametophyte, also called the embryonic sac.One sperm nucleus fertilizes the egg cell, forming a zygote, while the other sperm nucleus usually fuses with the binucleate central cell, forming a primary endosperm cell (its nucleus is often called the triple fusion nucleus).
The cells of the body's surface form the outer layer of skin. Inside the body, epithelial cells form the lining of the mouth and alimentary canal and protect these organs. Epithelial tissues help in the elimination of waste. Epithelial tissues secrete enzymes and/or hormones in the form of glands. Some epithelial tissue perform secretory functions.
Nuclear DNA is a nucleic acid, a polymeric biomolecule or biopolymer, found in the nucleus of eukaryotic cells.Its structure is a double helix, with two strands wound around each other, a structure first described by Francis Crick and James D. Watson (1953) using data collected by Rosalind Franklin.