What is the meaning of vesicles

Vesicle (cytology)

from Latin: vesicula - vesicles
English: vesicle

1 definition

Vesicle are spherical or ovoid intracellular structures about 50-100 nm in diameter that are surrounded by a simple membrane. In the electron microscopic sectional view, they appear as round or oval cavities.

2 function

Vesicles are separate compartments, the contents of which are separated from the cytoplasm. Lipids and proteins within a cell are transported from one organelle to the next via transport vesicles. For example, proteins that are formed in the ER are sorted into vesicles and brought to the Golgi apparatus.

Vesicles can also contain substances intended for exocytosis and intended to be secreted (e.g. neurotransmitters). If substances are absorbed into the cell through endocytosis, this also takes place through the formation of vesicles on the plasma membrane. The processes in which vesicles are involved are also known as vesicular transport.

The assignment of the vesicles to the organelles is inconsistent in the literature. According to some authors, they are not organelles in their own right, as they are only formed temporarily and then dissolve again when they fuse with an organelle such as the Golgi apparatus or lysosomes.

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3 types of vesicles

3.1 Lysosomes

Lysosomes arise from constrictions in the Golgi apparatus. They are responsible for the breakdown of cell components such as proteins, lipids, polysaccharides or the lysis of bacteria. They contain various hydrolases and have a low pH of 4.5-5.[1]

3.2 Transport vesicles

Transport vesicles move cell components within the cell, for example between the endoplasmic reticulum and the Golgi apparatus.

3.3 Secretory vesicles

Secretory vesicles enable the cell to secrete substances into its environment. These can be pollutants and degradation products, but also signal molecules such as hormones or neurotransmitters.

Synaptic vesicles are specific secretory vesicles of the neurons. They contain low molecular weight neurotransmitters that are released into the synaptic cleft in response to an action potential.[2]

3.4 peroxisomes

Peroxisomes build the toxic hydrogen peroxide (H.2O2) to hydrogen and oxygen. They do not arise from the Golgi apparatus, but multiply through division. The cells of the liver and kidneys contain a particularly large number of peroxisomes.[3]

3.5 Extracellular vesicles

Extracellular vesicles (EV) are released from cells and can be taken up by other cells. They are therefore an important means of intercellular communication.[4]

4 sources

  1. ^ Cooper, G. M. The cell: a molecular approach, The Mechanism of Vesicular Transport (2000).
  2. ^ Siegel, G. J. Basic neurochemistry: molecular, cellular and medical aspects. The Synaptic Vesicle Cycle in the Nerve Terminal 6th edn, (Lippincott-Raven Publishers, 1999).
  3. ^ Titorenko, V. I. & Rachubinski, R. A. The peroxisome: orchestrating important developmental decisions from inside the cell. J Cell Biol 164, 641-645, doi: 10.1083 / jcb.200312081 (2004).
  4. ↑ Furi, I., Momen-Heravi, F. & Szabo, G. Extracellular vesicle isolation: present and future. Ann Transl Med 5, 263, doi: 10.21037 / atm.2017.03.95 (2017)