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      Synthesis, folding, modification, and transport of proteins

      • endoplasmic reticulum (ER), in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins.
      www.britannica.com › science › endoplasmic-reticulum
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  2. Apr 25, 2024 · endoplasmic reticulum (ER), in biology, a continuous membrane system that forms a series of flattened sacs within the cytoplasm of eukaryotic cells and serves multiple functions, being important particularly in the synthesis, folding, modification, and transport of proteins.

    • Eukaryote

      eukaryote, any cell or organism that possesses a clearly...

    • Ribosome

      Ribosome, particle that is present in large numbers in all...

    • Lysosome

      lysosome, subcellular organelle that is found in nearly all...

    • Structure
    • Example
    • Functions
    • Roles
    • Morphology
    • Variations

    The endoplasmic reticulum (ER) is a large organelle made of membranous sheets and tubules that begin near the nucleus and extend across the cell. The endoplasmic reticulum creates, packages, and secretes many of the products created by a cell. The entire structure can account for a large proportion of the endomembrane system of the cell. As seen in...

    For instance, in cells such as liver hepatocytes that are specialized for protein secretion and detoxification, the ER can account for more than 50% of the total lipid bilayer of the cell. Similarly, the ER membrane system is particularly prominent in pancreatic beta cells that secrete insulin, or within activated B-lymphocytes that produce antibod...

    ER sheets appear to be crucial in the response of the organelle to stress, especially since cells alter their tubules-to-sheets ratio when the number of unfolded proteins increases. Occasionally, apoptosis is induced by the ER in response to an excess of unfolded protein within the cell. When ribosomes detach from ER sheets, these structures can di...

    Although ER sheets and tubules appear to have distinct functions, there isnt a perfect delineation of roles. For instance, in mammals tubules and sheets can interconvert, making the cells adaptable to various conditions. The relationship between structure and function in the ER has not been completely elucidated.

    The endoplasmic reticulum membrane system can be morphologically divided into two structurescisternae and sheets. Cisternae are tubular in structure and form a three-dimensional polygonal network. They are about 50 nm in diameter in mammals and 30 nm in diameter in yeast. ER sheets, on the other hand, are membrane-enclosed, two-dimensional flattene...

    The rough version of the endoplasmic reticulum is often closer to the nucleus, whereas the smooth endoplasmic reticulum is further from the nucleus. However, both versions are connected to each other and the nucleus through a series of small tubules.

    • Gabe Buckley
  3. Oct 3, 2015 · The endoplasmic reticulum (ER) is a large, dynamic structure that serves many roles in the cell including calcium storage, protein synthesis and lipid metabolism. The diverse functions of the ER are performed by distinct domains; consisting of tubules, sheets and the nuclear envelope.

    • Dianne S. Schwarz, Dianne S. Schwarz, Michael D. Blower
    • 10.1007/s00018-015-2052-6
    • 2016
    • Cell Mol Life Sci. 2016; 73: 79-94.
  4. The endoplasmic reticulum (ER) is a part of a transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum (RER), and smooth endoplasmic reticulum (SER).

  5. The ER has a central role in lipid and protein biosynthesis. Its membrane is the site of production of all the transmembrane proteins and lipids for most of the cell's organelles, including the ER itself, the Golgi apparatus, lysosomes, endosomes, secretory vesicles, and the plasma membrane.

    • Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, Peter Walter
    • 2002
    • 2002
  6. About. Transcript. During protein synthesis, proteins meant for use within the cell are translated by free ribosomes. Proteins meant to be embedded in the cell membrane or used outside the cell are translated by ribosomes attached to the rough endoplasmic reticulum.

    • 12 min
    • Sal Khan
  7. Nov 1, 2023 · The endoplasmic reticulum is the cell organelle that originates from the cells nuclear envelope, synthesizes protein, and transports the proteins for cellular metabolism. Depending on the cell, the endoplasmic reticulum can occupy 50% of the cell volume.

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