Vacuole (Ⅴ acuole) is composed of monolayer and its internal cell fluidOrganelle, mainly exists inplant cellMedium.Of lower animals, especially unicellular animalsFood bubble、Contractile vesicleThey also belong to vacuoles.[1]
Vacuoles are not the unique structure of plant cells, but the vacuoles of plant cells are larger and the differences between vacuoles are larger;andAnimal cellThe vacuoles were smaller and the difference between vacuoles was not significant;Or the vacuoles of some animal cells are not obvious.So the animal cells in the textbookSubmicrostructureNo vacuoles are drawn on the pattern diagram.But it cannot be said that animal cells do not have vacuoles, let alone vacuoles are the unique structure of plant cells.As early as the 1930s, the concept of vacuole system was proposed, including golgi vacuoles, lysosomes, spheroids, microsomesAutophagic vesicleResidues, pinocytosis vesicles, phagocytosis vesicles, aleurone vesicles, central vesicles, contraction vesicles, etc.It is believed that all vesicles or vacuoles surrounded by membranes can be counted as vacuoles in the vacuole system, and they are one of the components of animal and plant cells.[2]
Chinese name
vacuole[3]
Foreign name
vacuole
Nature
Vesicular structure in cytoplasm[4]
Features
Regulate the environment inside the cell and keep the cell osmotic pressure[1]
Composition
It is composed of monolayer and its internal cell fluid[1]
Vacuoles are vesicular structures in the cytoplasm.The vacuole membrane is separated from the cytoplasm and contains water like cell fluid.Juvenileplant cellThe middle vacuoles are small, and the mature plant cells have large vacuoles;The color of flowers, leaves and fruits, except for green, is mostly produced by pigments in the cell fluid of vacuoles.higherAnimal cellThe vacuoles in were not obvious;The food vacuoles and telescopic vacuoles of some unicellular animals have the functions of absorbing nutrients and excreting wastes respectively, which can also be said to be a form of vacuoles.[4]
Discovery History
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Naegeli (1844) has long believed that vacuoles are normal morphological components in plant protoplasm.From the early 19th century to the 1930s, French classical cytologists Guililermond, Dageard and Parat studied vacuoles by means of living staining, and proposed the term vacuole system.At that time, they believed that all vesicles that could be stained with neutral red belonged to the vacuole system.However, if this standard is followed, some specialized vacuoles with typical vacuole characteristics, such as aleurone vacuoles and spheres, will be excluded from vacuoles due to lack of affinity with neutral red.Until some scholars usedelectron microscopeAfter observation and research, it is believed that all vesicles surrounded by membranes in cells belong to vacuole system except mitochondria and plastids.Strictly speaking, a vacuole is a water filled area separated by a semipermeable membrane and a paste of colloidal cytoplasm.This semipermeable membrane is called vacuole membrane, and the liquid surrounded by vacuole membrane is often called cell juice.[5]
type
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vacuole
Vacuoles can be divided into the following types.Some are common to animal and plant cells, and some are unique to plant cells.[6]
Protoplasts from the pericarp of grape berries[7]
Golgi vacuole
A small bubble formed at the edge of the Golgi pool (or retention bubble) on the mature surface of the Golgi apparatus, which contains hydrolases, such asacid phosphataseEtc.[6]
lysosome
It is formed by endoplasmic reticulum, which also contains hydrolase.It may also be formed by Golgi apparatus.[6]
Spheroid
It is unique to plant cells, equivalent to lysosomes, and also formed by endoplasmic reticulum.[6]
Microbody
Their properties are determined according to the enzymes contained in them, which may occur from the endoplasmic reticulum.[6]
Digestive vesicle
A small vesicle formed by fusion of lysosome and phagosome or pinocytotic vacuole.[6]
Autophagocytes or autophagosomes
It is composed of a small part of cytoplasm surrounded by a membrane. The digested material is composed of various components contained in the cytoplasm, such as mitochondria and fragments of the endoplasmic reticulum.[6]
Remains
By digestive vesicle andAutophagic vesicleMaterials that cannot be digested are gradually accumulated and transformed.[6]
Pinocytosis vacuole
It is formed by swallowing some solution or nutrient solution due to the invagination of plasma membrane.[6]
Phagovesicles or phagosomes
It is formed by the invagination of plasma membrane engulfing nutrient particles.[6]
Aleurone granules or aleurone bubbles
A specific vacuole produced in the seeds of plants, which stores proteins (mostly enzymes) and originates from the endoplasmic reticulum.[6]
Central vacuole
Central vacuole[8]
It appears in the center of plant cells and becomes a huge central vacuole due to the enlargement and merger of many small vacuoles during the growth process. It is a unique structure of plant cells. For example, the large central vacuole of mature watermelon cells stores a lot of sugar and water, making watermelon sweet and juicy.The central vacuole also originated from the endoplasmic reticulum, which expanded from the endoplasmic reticulum pool.[6]
Contractile vesicle
The vacuoles contained in protozoa may also be expanded from the endoplasmic reticulum pool, which is flexible and can drain waste liquid or excess water out of the body when contracting.[6]
Property structure
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Animal and plant vacuoles are composed of a layer of biofilm, and their morphology is the same as that of endoplasmic reticulum membrane.The plant vacuole membrane has special permeability, which is generally higher than the plasma membrane.[6]
Animal vacuoles are the redox centers in animal cells, and are the places where substances, especially proteins, such as zymogen granules, yolk granules, acrosomes (perforators), are concentrated and coagulated.[6]
Vacuoles contain many substances. Vacuoles of plant cells contain inorganic salts, organic acids, sugars, lipids, proteins, enzymes, gums, mucus, tannins, alkaloidsAnthocyaninEtc.In animalsSecretory cellIt contains a large number of glycogen particles manufactured and exported in the form of zymogen;The lysosomes of animals and plants contain high concentrations of various enzymes, such as protease, nuclease, esterase and nucleosidase.[6]
The liquid in plant vacuoles is called cellsap, in which inorganic salts, amino acids, sugars and various pigments are dissolved, especiallyanthocyanin(anthocyanin), etc.Cell fluid is hypertonic, so plant cells can always be in a state of imbibition and fullness.Anthocyanins in cell fluid are related to plant color. Purple and dark red of flowers, fruits and leaves are determined by anthocyanins.In addition, vacuoles are also places for collecting plant metabolic wastes, which are deposited in vacuoles in the form of crystals.[6]
Fungal cellThe middle vacuoles are similar to the vacuoles in plant cells. They originate from large vesicles of smooth endoplasmic reticulum or Golgi apparatus, or are formed by plasma membrane, which is the result of pinocytosis or phagocytosis of plasma membrane.The shape of vacuoles varies greatly. Their size and number increase with the age of bacteria or the aging of hyphae. Small vacuoles can fuse with each other and increase. Large vacuoles can also be divided into many small vacuoles.The vacuole is surrounded by a single membrane, and its composition is not yet clear, but the contents of the vacuole are relatively special, mainlyBasic amino acid, such as arginine, ornithine, citrulline, glutamine, etc., the hydrogen base acid in the vacuole often moves away from the vacuole.The polyphosphate molecules used are also stored in vacuoles.At the same time, there are many enzymes in the vacuole, such as protease, acid phosphatasealkaline phosphataseNuclease, cellulase, etc.Its main function is to store various amino acids, enzymes and other nutrients, and regulate the osmotic pressure of mycelium, as well as the function of lysosome.[9]
function
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Vacuoles play a role in regulating the internal environment of cells, and can keep cells in a certain osmotic pressure and expansion state.[1]
The large central vacuole is of great significance to living plant cells. It not only stores organic metabolites, but also participates in the biochemical cycle of substances in cells.And because its cell fluid is a solution with high concentration, it is directly related to the absorption and transportation of water in plants and the maintenance of cell tension.[1]
Vacuoles in cells
The function of vacuoles is multifaceted, and its obvious role is to maintain cell tension.The second is to store various substances. For example, sucrose in sugar beet is stored in vacuoles, and the color of many flowers is the result of pigment concentration in the vacuoles of petal cells.Third, the vacuoles contain hydrolase, which can engulf the destroyed components in digestive cells.Finally, vacuoles also play a role in the autolysis of plant cells.Some senescent and degenerated cells in plants are digested by autolysis.At this time, the vacuole is destroyed, and the hydrolase in it is released, leading to the decomposition of cell components and cell death.For example, about 80% of RNA in the cotyledon of Silkworm bean is gradually decomposed within the first 30 days of seed ◎ vacuole germination.But if the vacuole is destroyedRibonucleaseIf released, it can be used within a few hoursRibosomal RNADecomposition completed.This means that once the vacuole is destroyed, the hydrolase is released, which can quickly make the cell autolyse.[1]
There are vacuoles of different sizes in plant cells.Mature plant cells have a large central vacuole, which may account for 90% of the cell volume. It is composed of many small vacuoles.The vacuoles in animal cells are small, and the difference is not significant.The vacuole is surrounded by a unit membrane, the main component of which is water.The vacuoles of different kinds of cells contain different koji substances, such as inorganic salts, sugars, lipids, proteins, enzymes, gums, tannins, alkaloids, etc.[1]
Special role
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In plant cells, most of the vacuole proteins are synthesized in the form of macromolecular precursors on the endoplasmic reticulum, and then transported to the vacuoles, one at the C-terminalAsparagineResidue passingProteolytic enzymeThe shear of the two into their own mature forms.Vacuolar processing enzyme (VPE) is aCysteine protease, para asparagine andAspartateResidues are substrate specific and play an important role in vacuolar protein processing and activation.VPE was first found in pumpkin seeds during ripening. Later, VPE was also extracted from castor seeds, which plays an important role in the maturation of seed storage proteins.Studies have shown that VPE also exists in senescent tissues and vegetative tissues under certain stress conditions. This vegetative VPE is found in plant cellsProcedural deathPlay an important role in.[10]
