Eukaryotic cells are characterized by a complex structure. Its main components are the plasma membrane, the cytoplasm, which contains membrane organoids, inclusions, organoids without membranes and the nucleus.
Membrane organoids have one or two membranes. They are constant elements of the cell, characterized by a peculiar structure and perform the corresponding functions.
The two-membrane structures of the cell include the cell nucleus, mitochondria, as well as plastids (chloro-, chromo- and leukoplasts). Non-membrane elements are ribosomes and the cell center.
During the cell cycle, the elements of the cytoskeleton may change. So, for example, during the division process, cytoplasmic tubes disappear in the cell, a new structure appears - the division spindle.
Single-membrane organoids: dwell on their characterization.
These structures are components of
eukaryotic cells that are separated from the cytosol by a single membrane. Single-membrane
organelles of the cell include the endoplasmic reticulum, the Golgi apparatus, and lysosomes derived from it.
The endoplasmic reticulum is a closed system of tubules that permeate the entire cytosol. It divides the cell into separate parts and is responsible for the transport of substances. The endoplasmic reticulum was opened in 1945 using an electron microscope, which allowed us to see a particularly loose structure throughout the cytoplasm.
The endoplasmic reticulum is granular and agranular. A smooth (agranular) endoplasmic reticulum is responsible for the synthesis of lipids and polysaccharides, and the granular network contains ribosomes on its surface in which proteins are formed. This structure promotes the transfer of various compounds throughout the cell, providing the circulation of nutrients.
It is worth noting that the tanks of the granular reticulum bind to the membrane of the nucleus and take part in the formation of new nuclear membranes, which are formed after cell division.
The Golgi apparatus can be of various shapes, but in most cases it has the form of thickened discs that form a dictiosome. From the dictiosomes leave the tubes, at the end of which the bubbles are concentrated. In the Golgi apparatus, substances are accumulated that are synthesized in the cell and removed from it. This organelle is well developed in glandular cells.
Its vesicles take part in the formation of the cytoplasmic membrane, as well as individual organelles - primary lysosomes.
Lysosomes are round-shaped membrane structures containing enzymes by which the cell is able to cleave various
organic substances. These single-membrane organoids perform another function - they break down some structural elements of cells without affecting its functioning, providing an additional source of nutrition with insufficient intake of nutrients. In addition, lysosomes are responsible for the destruction of dead and unnecessary organoids.
It should be noted that all single-membrane organoids are important for maintaining cellular homeostasis, since they ensure the normal functioning of cells.