vesicle

(noun)

A membrane-bound compartment found in a cell.

Related Terms

Examples of vesicle in the following topics:

  • Vesicles and Vacuoles

    • Vesicles and vacuoles are membrane-bound sacs that function in storage and transport.
    • Vesicles can fuse with the plasma membrane to release their contents outside the cell.
    • Vesicles can also fuse with other organelles within the cell.
    • Vesicles perform a variety of functions.
    • Vesicles are involved in metabolism, transport, buoyancy control, and enzyme storage.

  • Exocytosis

    • The first stage is called vesicle trafficking.
    • The next stage that occurs is vesicle tethering, which links the vesicle to the cell membrane by biological material at half the diameter of a vesicle.
    • Next, the vesicle's membrane and the cell membrane connect and are held together in the vesicle docking step.
    • The final stage, vesicle fusion, involves the merging of the vesicle membrane with the target membrane.
    • In exocytosis, vesicles containing substances fuse with the plasma membrane.

  • The Golgi Apparatus

    • We have already mentioned that vesicles can bud from the ER and transport their contents elsewhere, but where do the vesicles go?
    • The transport vesicles that formed from the ER travel to the cis face, fuse with it, and empty their contents into the lumen of the Golgi apparatus.
    • Finally, the modified and tagged proteins are packaged into secretory vesicles that bud from the trans face of the Golgi.
    • While some of these vesicles deposit their contents into other parts of the cell where they will be used, other secretory vesicles fuse with the plasma membrane and release their contents outside the cell.
    • Several vesicles can be seen near the Golgi apparatus.

  • Synaptic Transmission

    • The synaptic vesicles fuse with the presynaptic axon terminal membrane and empty their contents by exocytosis into the synaptic cleft.
    • Fusion of a vesicle with the presynaptic membrane causes neurotransmitters to be released into the synaptic cleft.
    • This pseudocolored image taken with a scanning electron microscope shows an axon terminal that was broken open to reveal synaptic vesicles (blue and orange) inside the neuron.
    • The calcium entry causes synaptic vesicles to fuse with the membrane and release neurotransmitter molecules into the synaptic cleft.

  • The Mitotic Phase and the G0 Phase

    • During prophase, the "first phase," the nuclear envelope starts to dissociate into small vesicles.
    • There, the vesicles fuse and coalesce from the center toward the cell walls; this structure is called a cell plate.
    • As more vesicles fuse, the cell plate enlarges until it merges with the cell walls at the periphery of the cell.
    • In plant cells, Golgi vesicles coalesce at the former metaphase plate, forming a phragmoplast.
    • A cell plate formed by the fusion of the vesicles of the phragmoplast grows from the center toward the cell walls and the membranes of the vesicles fuse to form a plasma membrane that divides the cell in two.

  • Endocytosis

    • The pocket pinches off, resulting in the particle being contained in a newly-created intracellular vesicle formed from the plasma membrane.
    • Once the vesicle containing the particle is enclosed within the cell, the clathrin disengages from the membrane and the vesicle merges with a lysosome for the breakdown of the material in the newly-formed compartment (endosome).
    • Pinocytosis results in a much smaller vesicle than does phagocytosis, and the vesicle does not need to merge with a lysosome .
    • The vacuoles or vesicles formed in caveolae (singular caveola) are smaller than those in pinocytosis.

  • Intermediate Filaments and Microtubules

    • Microtubules are part of the cell's cytoskeleton, helping the cell resist compression, move vesicles, and separate chromosomes at mitosis.
    • They help the cell resist compression, provide a track along which vesicles move through the cell, and pull replicated chromosomes to opposite ends of a dividing cell.

  • Regulatory Mechanisms for Cellular Respiration

    • GLUT4 is a glucose transporter that is stored in vesicles.
    • A cascade of events that occurs upon insulin binding to a receptor in the plasma membrane causes GLUT4-containing vesicles to fuse with the plasma membrane so that glucose may be transported into the cell.

  • Excitation–Contraction Coupling

    • The Ca2+ ions allow synaptic vesicles to move to and bind with the presynaptic membrane (on the neuron) and release neurotransmitter from the vesicles into the synaptic cleft.

  • Cell Structure, Metabolism, and Motility

    • Amoebas and some other heterotrophic protist species ingest particles by a process called phagocytosis in which the cell membrane engulfs a food particle and brings it inward, pinching off an intracellular membranous sac, or vesicle, called a food vacuole .
    • The vesicle containing the ingested particle, the phagosome, then fuses with a lysosome containing hydrolytic enzymes to produce a phagolysosome, which breaks down the food particle into small molecules that diffuse into the cytoplasm for use in cellular metabolism.