cytoplasm

Granular substances surrounded by cell plasma membrane

Collection

zero Useful+1

zero

This entry is made by Compilation and application of scientific encyclopedia entries of "Science Popularization China" to examine.

Cytoplasm is Cell plasma membrane The general term for all semi transparent, gelatinous and granular materials surrounded except the nuclear area. The water content is about 80%. The main components of cytoplasm are ribosome , storage materials, various enzymes and intermediate metabolites, various nutrients and monomer of macromolecules, etc., and a few bacteria thylakoid , carboxylosome, bubble or Parasporal crystal Etc.

The cytoplasm consists of Cytoplasmic matrix 、 Endometrial system 、 Cytoskeleton It is the main place of life activities. The cytoplasm consists of matrix, organelles and inclusions, which are transparent and gelatinous under living conditions. The matrix refers to the liquid part of the cytoplasm, which is the basic component of the cytoplasm and mainly contains a variety of soluble enzymes, sugars inorganic salt And water, etc. Organelle It is a structure distributed in the cytoplasm, with a certain shape, and plays an important role in cell physiological activities. It includes: mitochondrion Chloroplasts, plastids, endoplasmic reticulum, Golgi apparatus, cytoskeleton (microfilaments, microtubules, intermediate fibers) of vacuolar system (lysosomes, vacuoles), centrioles and surrounding substances, etc.

Chinese name: cytoplasm
Also called: Cytoplasm

Form: Transparent jelly
Basic components: stroma
Reading: xì bāo zhì

catalog

brief introduction

Announce

edit

Cytoplasm is the general term for all translucent, colloidal and granular materials inside the cell membrane and outside the nucleus. The cytoplasm includes matrix, organelles and inclusions, which are transparent and gelatinous in vivo. The water content of the cytoplasm is about 80%, and the main components are ribosomes, storage materials, various enzymes and intermediate metabolites, plasmids, various nutrients and monomer of macromolecules, etc. A few bacteria also have thylakoids, carboxyl enzyme bodies, bubbles or parasporal crystals, etc. Cytoplasmic matrix, also known as cytoplasmic sol, is a homogeneous and translucent colloidal part of cytoplasm, filled between other visible structures, and is the basic component of cytoplasm, which mainly contains a variety of soluble enzymes, sugars, inorganic salts and water. The main function of the cytoplasmic matrix is to provide the necessary ionic environment for various organelles to maintain their normal structure, and to supply all materials needed for various organelles to complete their functional activities. The cytoplasm is the main place for metabolism, and the vast majority of chemical reactions are carried out in the cytoplasm. It also regulates the nucleus^[1] 。

form

Announce

edit

Cytoplasm, also known as cytoplasm, is composed of Cytoplasmic matrix 、 Endometrial system 、 Cytoskeleton And inclusion.

Cytoplasm includes matrix Organelle and Inclusions , which is transparent and gelatinous under living conditions.

The matrix refers to the liquid part of the cytoplasm, which is the basic component of the cytoplasm. It mainly contains a variety of soluble enzymes, sugars, inorganic salts and water.

Organelles are distributed in the cytoplasm, have a certain shape, and play an important role in cell physiological activities. It includes: mitochondrion 、 chloroplast 、 Endoplasmic reticulum 、 Intranet 、 Golgi apparatus 、 lysosome 、 Microfilament , microtubule Centriole , ribosome, etc.

Cytoplasmic matrix

Announce

edit

Schematic diagram of cytoplasm

Cytoplasmic matrix Cytoplasmic sol Cytosol is a homogeneous and translucent colloidal part in the cytoplasm, which is filled between other tangible structures. The chemical composition of cytoplasmic matrix can be divided into three categories according to its molecular weight, namely Small molecule , medium and large molecules. Small molecules include water Inorganic ion ； The middle molecular weight includes lipids, sugars amino acid Nucleotides and their derivatives; Macromolecules include polysaccharides, proteins Lipoprotein And RNA, etc. The main function of the cytoplasmic matrix is to provide the necessary ionic environment for various organelles to maintain their normal structure, to supply all substrates for various organelles to complete their functional activities, and also to conduct some biochemical activities.

Endometrial system

Announce

edit

Endomembrane system is a complex system evolved by invagination of cell membrane. It forms various organelles, such as endoplasmic reticulum Golgi complex , lysosomes, etc. These organelles are isolated and sealed Compartment , each with a unique set of enzymes, performing specific physiological functions.

Endoplasmic reticulum

Endoplasmic reticulum (ER) is a flat cystic or tubular vesicular membranous structure, which anastomoses with each other by branches to form a network, and the surface of which has ribonucleoprotein s bodies attached is called Rough endoplasmic reticulum (rough endoplasmic reticulum, RER), no adhesion on the film surface Riboribosome Is called Smooth endoplasmic reticulum (smooth open-ended reticulum, SER).

Ribonucleoprotein Body attached to Endoplasm On the Internet, its main function is synthesis Secretory protein Quality (e.g immunoglobulin 、 digestive enzyme Etc.), but also some Structural protein (e.g. membrane mosaic protein , lysosomal enzymes, etc.). The rough endoplasmic reticulum is distributed in most cells, while the rough endoplasmic reticulum is distributed in cells with strong protein secretion (such as plasma cells 、 Glandular cell ）The rough endoplasmic reticulum is particularly developed, and its flat cysts are densely lamellar and occupy a large part of the cytoplasm. Generally speaking, the functional state and differentiation degree of cells can be judged according to the development degree of rough endoplasmic reticulum.

Cytoplasmic endoplasmic reticulum

The smooth endoplasmic reticulum is mostly tubular vesicular, which is only abundant in some cells, and has different functions due to different acids, ① Steroid hormone The synthesis of, in the cell that secretes steroid hormone; The smooth endoplasmic reticulum membrane has the enzyme system required for cholesterol synthesis, and the cholesterol synthesized here is converted into steroid hormone; ② Lipid metabolism, the absorption cells of the small intestine absorb fatty acids, glycerol and Monoglyceride , esterified to triglyceride ， Hepatocyte The fatty acid ingested is also found on the smooth endoplasmic reticulum Oxidoreductase Decomposition, or re esterification; ③ Detoxification. The smooth endoplasmic reticulum of hepatocytes contains various enzymes involved in the detoxification. Some foreign drugs, toxic metabolites and hormones are oxidized and reduced here, hydrolysis Or combined with other treatments to become non-toxic substances discharged from the body; ④ Ion Storage and Regulation, Transverse muscle cells The smooth endoplasmic reticulum, also known as sarcoplasmic reticulum, has a calcium pump on its membrane, which can pump and store Ca2+in the cytoplasmic matrix, leading to muscle cell relaxation. Under the action of specific factors, the stored Ca2+is released, causing muscle cell contraction. stomach Basal gland Parietal cell The smooth endoplasmic reticulum has a chlorine pump, which releases CI - when hydrochloric acid is secreted, and participates in the formation of hydrochloric acid.

Golgi complex

(Golgi complex) consists of three parts: flat cyst, vesicle and bulla. Its imitative distribution and quantity in cells vary according to the type of cells. The saccule has 3-10 layers, which are closely arranged in parallel to form the main body of the Golgi complex. It has one side that is often convex and supersymmetric forming face, and the other side that is concave. There is a hole on the flat soup that is called mature face and faces the generating face. There are some vesicles near the generating surface, with a diameter of 40~80nm, which are generated from the buds of the nearby rough endoplasmic reticulum and transport the protein synthesized in the rough endoplasmic reticulum to the flat capsule. Therefore, the vesicles are also called Transport vesicle 。 Vacuole is located on the mature surface and is the product of Golgi complex, including lysosome Secretory vesicle Etc. Lysosomes gradually leave the Golgi complex and disperse to various parts of the cell. Secretory vesicles fuse with each other, and their contents electron density It increases and becomes secretory granules. Golgi complexes are well developed in cells with strong protein secretion. Golgi complex processes, modifies, saccharifies and concentrates proteins from rough endoplasmic reticulum to make them mature proteins, such as Islet B cells The pre insulin is processed into insulin. Golgi complex has a variety of Glycosyltransferase , many proteins are Saccharification formation glycoprotein 。 In addition, a variety of lysosomes also form in the Golgi complex Primary lysosome 。

lysosome

(lysosome) is a membrane wrapped body containing a variety of acid hydrolases, such as acid phosphatase 、 cathepsin 、 Collagenase 、 Ribonuclease 、 Glucoside Acids and lipases can decompose various endogenous or exogenous substances. Their optimum ph is 5.0. The lysosomes in different cells are different (but they all contain acid phosphatase, so this enzyme is lysosomal Marker enzyme 。 According to whether lysosomes contain digested substances（ substrate ）It can be divided into primary lysosome and Secondary lysosome (secondary lysosome)。

(1) Primary lysosome: also called Prolysosome (protolysosome)。 It is generally round or oval, and its diameter is mostly between 25~50nm. Now it is found that there are also long rod or slow lysosomes. Its contents are homogeneous, electron density Medium or high substrate free. In a few cells, such as bone cell And inflammatory sites Neutrophils ， Lysosomal enzyme Can be released to play outside the cell Hydrolysis

Cytoplasmic lysosome

(2) Secondary lysosome: also known as phagolysosome, it is composed of secondary lysosome and various phagocytosis substrates to be hydrolyzed, so it is large in size, diverse in shape, and its contents are non Homogeneous Shape. According to the different sources of waste, it can be divided into Autophagic lysosome and Heterophagy lysosome 。 The role of autophagic lysosome substrate It is endogenous, that is, it comes from aging and disintegrating organelles or local cytoplasm in cells. The acting substrate of heterophago lysosome is via cells Swallow a drink Or ingested by phagocytosis, lysosomes and Phagosome It is formed by fusion, mostly seen in neutrophils engulfed by bacteria and foreign bodies macrophage 。 Some substrates in the synphage lysosome and autophagic lysosome are decomposed into monosaccharide , amino acids and other small molecules, which can enter the cytoplasm matrix through lysosomal membrane and be used by cells; Some can not be digested (such as foreign matters such as dust, metal particles, and some lipid components of aging organelles). They remain in the lysosome. When the lysosomal enzyme activity is exhausted and the lysosomal body is completely occupied by residues, it is called residual body. In mammals, residual bodies are retained in cells, and the common residual bodies are lipofuscin granules and medullary structures. They all evolved from autophagic lysosomes. Lipofuscin granule is irregular, which is composed of electron density Composed of different substances and fat drops, it is brown under the light microscope, and is mostly found in nerve cells Cardiac myocyte Hepatocytes and cells secreting steroid hormones increase with age. The interior of myelin figure is a large number of lamellar membranes, which may be caused by indigestion of membranous components. Primary lysosome and Swallow a drink The vesicles or other vesicles are fused to form Polyvesicular body (multilateral body), its outer boundary membrane contains many low electron density vesicles, and the matrix has acid squamose activity.

mitochondrion

(mitochondria) is usually rod or oval, with a transverse diameter of 0.5~1 η m and a length of 2~6 η m. However, the shape, size and number of mitochondria in different types of shock cells are very different. Under electron microscope, mitochondria have a double membrane, adventitia Smooth, 6-7nm thick, 2-3 nm pores in the film, and materials with molecular weight less than 10000 can pass freely; intima The thickness is 5-6nm, and the permeability is small. There is about 8 nm between the outer membrane and the inner membrane. Intermembrane cavity , or external cavity. It is formed by folding the membrane inward Mitochondrial crista (mitochohdrial crista), which is filled with Mitochondrial matrix 。 Scattered particles are often seen in the matrix, with a diameter of 25-50nm. Electron dense tropism Hungry acid Matrix particle (matrix granule), mainly composed of phospholipid protein, and containing calcium, magnesium, phosphorus and other elements. In addition to matrix particles, the matrix also contains lipids, proteins DNA molecule Ribosomes. There are many sessile spherules on the crista membrane of mitochondria, namely Grana (elementary particle), whose diameter is 8~10nm, consists of head, handle and substrate. spherical Its head is connected with the handle and protrudes from the surface of the intima, and the substrate is embedded in the Membranous lipid Medium.

The grana contains ATP synthase , can use respiratory chain The energy generated is combined into ATP and Energy storage In ATP. About 95% of the energy required for cell life activities is provided by mitochondria in the form of ATP, so mitochondria are cells energy metabolism In the center, the mitochondrial ridge actually expands the area of the inner membrane, so metabolic rate High energy consuming cells. The mitochondria cristae of most cells are lamellar. The cristae of rod-shaped mitochondria are mostly arranged perpendicular to their long axis, and the cristae of round mitochondria are mostly arranged radially from the periphery to the center; In a few cells, the cells that mainly secrete steroid hormones (such as adrenal cortex Cells, etc.), mitochondria are mostly tubular or vesicular; Some cells (such as hepatocytes) have both lamellar and tubular mitochondria.

Another functional feature of mitochondria is that they can synthesize some proteins. Now, scientists speculate that the proteins synthesized in mitochondria account for about 10% of all mitochondrial proteins. These proteins are highly hydrophobic and bind to the inner membrane. Mitochondrial synthetic proteins are synthesized according to the coding of the nuclear genome. without nuclear inheritance Mitochondrial RNA could not be expressed. Therefore, it indicates that mitochondria can become semi autonomous proteins.^[3]

As for the mechanism of mitochondrial formation, it is generally accepted that mitochondria proliferate by division. The development of mitochondria can be divided into two stages. In the first stage, the membrane of mitochondria grows and replicates, and then divides and proliferates. The second stage includes the differentiation process of mitochondria itself, which can be completed Oxidative phosphorylation Functional mechanism. The growth and differentiation stages of mitochondria are controlled by two independent genetic systems, so it is not a completely self replicating entity.

Catalase body

Peroxisomes (peroxinome) Microbody (microbody) is a round body wrapped with membrane, with a diameter of 0.2~0.4 μ m, which is mainly found in hepatocytes and Renal tubule Epizootic cells. The content of people is low electron density Of Homogeneous Shape; In some animals, the electronic dense core is uric acid Hydrogenase Crystallization. Peroxides contain more than 40 enzymes. Different cells contain different kinds of enzymes, but catalase exists in the peroxisomes of all cells. Various oxygenases can make corresponding substrate Oxidation: in the process of oxidizing the substrate, the oxidase reduces oxygen to hydrogen peroxide, and catalase It can reduce hydrogen peroxide to water. such oxidation reaction In liver Renal cell Is very important.

ribosome

(ribosme) is created by Ribosomal RNA The elliptical dense particles composed of (rRNA) and protein are not membrane structures, and the particle size is about 15nm × 25nm. The ribosome consists of a Large subunit With a Small subunit Composition. The large subunit contains two rRNAs and about 40 related protein molecules, with a central gene; The small subunit contains one rRNA and about 40 related protein molecules, and the non functional ribosome exists alone. When a certain number of ribosomes (3~30) pass through their large and small subunits by a mRNA filament to connect them, they become functional Polyribosome (polyribosomes), in the shape of beads or flower clusters under the electron microscope. Ribosome can translate the nucleotide code contained in mRNA into amino acid sequence, namely Peptide chain Synthetic peptide chains are released from the central tube of large subunits, and can further polymerize to form Free ribosome (free ribosomes) Synthesize structural proteins of cells themselves, such as cytoskeleton proteins Cell matrix Enzymes, etc., for cell metabolism, proliferation and growth needs. Therefore, there are a lot of free ribosomes in cells in vigorous proliferation. to Endoplasm Attached ribosomes on the surface of the omentum mainly synthesize structural proteins Secretory protein 。 Ribosome rich cells with basophilic cytoplasm under light microscope.

Cytoskeleton

Announce

edit

The specific shape and movement of cells depend on the network structure of protein filaments in the cytoplasm - cytoskeleton. The cytoskeleton is composed of microtubules, microfilaments Intermediate filament and Micro beam net form.

microtubule

(microtubule) is a thin and long hollow cylindrical structure. The pipe diameter is about 15nm, the length is different, and the constant roots are arranged in parallel. Microtubules are composed of Tubulin (thbulin). Tubulin monomer is about 5 nm in diameter Globular protein They are connected into fibrils in series, and 13 fibrils are arranged in longitudinal parallel to form microtubules. Microtubules include single microtubules Duplex microtubule Three types of pipes are made with triplet. Most microtubules in cells are single microtubules Colchicine It is easy to depolymerize into tubulin under the condition of crop average, so it belongs to unstable microtubule. Duplex microtubules are mainly located in cilia And sperm Flagellum Middle and triple microtubules participate in the formation Centrosome And matrix were stable microtubules.

Microtubules have many functions. The scaffold function of microtubules can maintain the shape of cells. For example, the circular microtubules around platelets make them biconvex and disc shaped, and the microtubules of nerve cells support their protrusions. If colchicine is added, the microtubules depolymerization The platelets become round and the neurite shrinks. Microtubules are involved in cell movement, such as cell division Composed of microtubules Spindle Can make chromosome Move toward the poles. If colchicine is added, the division stops at the middle stage, and the cilia and flagella swing Endocytosis and Exocytosis Microtubules are involved in the transport of intracellular substances.

Microfilament

(microfilament) widely exists in a variety of cells, and microfilaments often exist in groups or bundles. In some highly specialized cells (such as muscle cells), they can form stable structures, but more commonly form unstable bundles or complex networks. They can be cell cycle and motion state To change its morphology and spatial location And can polymerize or disaggregate according to different states of cells.

Cytoskeleton diagram

The microfilaments distributed in muscle cells and non muscle cells are divided into thin filaments and thick filaments. The thin filament has a diameter of about 6nm and a length of about 1 μ m, mainly composed of Actin (actin) composition, so it is also called Actin filament (actinfilament), which is usually referred to as microfilament. Cytochalasin B Can make filaments depolymerization To inhibit Cell movement ； The thick filament is 10-15nm in diameter and about 1.5 μ m in length, mainly composed of Myosin (myosin), so it is also called myosin filament. Microfilament is a constant structure in muscle cells. In striated muscle cells; Fine filaments and thick filaments are regularly arranged into myofibrils in a certain proportion (about 2:1), and their contraction mechanism has been clarified. smooth muscle cell The ratio of inner filaments to thick filaments is about 15:1, and the arrangement of the two is irregular. In general, only fine filaments can be seen in non muscle cells, while thick filaments may be difficult to observe due to their short existence time or depolymerization into myosin during the preparation of electron microscope specimens. Under the action of some factors, the microfilaments in non muscle cells rapidly resolved into their structural proteins; Under the action of opposite factors, the structural protein is assembled into microfilaments. The filaments are cross-linked to form a network to form a part of the cytoskeleton and maintain the glial state of the cytoplasmic matrix; The local interaction between the filament and the thick filament can cause motion. In actively moving cells (mainly around the cytoplasm) or in local cells (such as Pseudopodia ）, and the parts requiring mechanical support (such as microvilli ）, are rich in microfilaments. Therefore, in addition to supporting function, microfilaments also participate in cell contraction Deformation movement 、 cytoplasmic streaming , cytoplasmic division, and Endocytosis 、 Exocytosis Process.

Intermediate filament

(intermediate fiber), also known as medium fiber, is about 8~11nm in diameter, between fine and thick filaments, hence its name. The intermediate filaments can be divided into five types, each composed of different proteins. In adults, most cells only contain one intermediate filament, so they have Tissue specificity And relatively stable. The five intermediate filaments are similar in shape and difficult to distinguish. But with Immunohistochemistry Methods can distinguish them and further analyze the types of cells.

(1) Keratin Keratin filament: distributed in epithelial cells , on Stratified squamous epithelium It is especially abundant in cells and often gathers into bundles, also known as Tension wire （tonofilament)。 Tension wire attached to Desmosome (One Cell junction ）, which can strengthen the connection between cells. In addition to supporting function, tension wire can also help maintain the toughness and elasticity of cells.

(2) desmin filament (desmin filament): It is distributed in muscle cells. In striated muscle cells, the fine network formed by desmin filaments connects adjacent myofibrils and aligns myomere positions; stay Z film At the thigh, the fine mesh surrounds the myofibrils and connects with the cell membrane. In smooth muscle cells, desmin filaments connect between dense bodies and dense spots to form a three-dimensional grid, and connect with actin filaments. In conclusion, desmin filaments, as the cytoskeleton network of muscle cells, play a role of fixation and mechanical integration.

(3) Vimentin Vimentin filament: mainly exists in fibroblasts and comes from embryo Mesenchyme Cells. There are two kinds of Intermediate filament Of cells, vimentin filament Vimentin filament is one of them. Vimentin filament mainly forms a grid around the nucleus to mechanically support the nucleus and stabilize its position in the cell.

(4) Neurofilament (neurofilament): Soma And protuberance, by Neurofilament protein With microtubules to form cytoskeleton and assist in material transport.

(5) Glial filament (neural filament): mainly exists in Astrocyte Inside, it is composed of glial fibrillary acidic protein, which gathers into bundles, interweaves and runs in the cell body, and extends into the process.

Micro beam net

(microtrabecular lattice) is a three-dimensional grid formed by interweaving fibers with a diameter of 3-6 nm, which was observed in intact cells by ultrahigh pressure electron microscopy and other techniques. Some people think it is a kind of micro beam grid embedded in other fiber systems. Others believe that it is composed of microtubules, microfilaments and Intermediate filament The system is closely connected and interlaced, or some are ground

The image of damaged cytoskeleton. In short, it is still a controversial structure.

Centrosome

Announce

edit

Centrosome is mostly located around the nucleus and consists of a pair of mutually perpendicular centrioles. The centriole is a short cylinder with a length of 0.5 μ m and a diameter of 0.2 μ m, which is compact by nine sets of triple microtubules and a small amount of electrons Homogeneous The shape forms its wall. The adjacent triple microtubules are arranged obliquely with each other, like windmill rotors. Nine spherical centriolar satellites can sometimes be seen on the outside of the wall. The size is about 70nm. During cell division, centriole satellite starting point formation Spindle , participate in the separation of chromosomes (see "Cell Cycle" for details). Cells with cilia or flagella, centriole formation matrix , participate in the formation of microtubule group.

Inclusion

Announce

edit

There is no metabolic activity in the cytoplasm itself, but there is a specific structure. Some are stored energy materials, such as sugar source particles and fat drops; Some are Cell product , such as secretory granules and melanin granules; The remains can also be regarded as inclusions.

Glycogen granule

(glycogen granule) is the existing form of glucose stored by cells, which is red in PAS reaction. Under electron microscope electron density High, no film wrapped, and in two types: β particles, 20~30nm in diameter, irregular in shape and dispersed. It is mainly found in muscle cells; Alpha particles, aggregates of beta particles, are flower clusters with different sizes, and are mostly found in hepatocytes.

Fat drop

Cellular structure

Fat drop is the existing form of cell storage lipids, which contains triglycerides, fatty acids, cholesterol, etc. Fat drops on fat cells Among them, the cells that secrete steroid hormones are the most, followed by the cells that secrete steroid hormones. In the former, a fat drop usually occupies most of the space of the cell; In the latter case, they are mostly small balls. During the preparation of ordinary light microscope specimens, fat droplets are xylene , ethanol dissolves and leaves vacuoles of different sizes. Under the electron microscope, the fat drops are not wrapped with film, and most of them have low or medium electron density, which is related to the unsaturated degree of the fatty acid contained.

Secretory granules

(secret granule) Common in various gland cells, containing enzymes, hormones, etc Bioactive substances 。 The shape, size and distribution position of secretory granules in cells vary with the type of cells, but they are all wrapped by membranes^[2] 。

Cytoplasmic inheritance

Announce

edit

Cytoplasmic inheritance The material basis of DNA is the DNA in the cytoplasm. Cytoplasmic genetics is widely used in practice.

concept

from Cytoplasmic gene The determined genetic phenomena and laws are also called non Mendelian inheritance and extranuclear inheritance.

characteristic

1. The phenotype of offspring is like the mother (also called Matrilineal inheritance , maternal inheritance);

2. Do not follow Mendelian inheritance, and the offspring do not have a certain proportion;

3. Orthogonal sum Backhand The phenotype of offspring is different.

mechanism

A zygote formed in the union of sperm and egg. It is provided by the parents genetic material Unequal Protoplast The nucleus comes from both parents, while the cytoplasm almost completely comes from the mother (the cytoplasm is rarely or even cannot enter when the sperm is fertilized Egg cell Medium).

During cell division, cytoplasmic genes are unevenly distributed, so cytoplasmic inheritance does not follow Mendel's law 。

material basis

Mitochondrial genome (mtDNA)

Chloroplast genome (ctDNA CpDNA)

Cell Symbiosis Genome

Bacterial plasmid genome

wrong Organelle genome

Organelle genome

Cytoplasmic genome

Chloroplast genome

1. Difference between nuclear inheritance and cytoplasmic inheritance

(1) The genetic material of both nucleus and cytoplasm is DNA molecule, but the distribution position is different. The genetic material inherited from the nucleus is in the nucleus, and the genetic material inherited from the cytoplasm is in the cytoplasm.

(2) The genetic bridge between nucleus and cytoplasm is gamete However, the nuclear genetic material of male and female gametes is equal, while the cytoplasmic genetic material mainly exists in the egg cell.

(3) The character expression of nucleus and cytoplasm is mainly through somatic cell Conducted. The carrier (chromosome) of nuclear genetic material has an equal division mechanism, and the equal division follows the genetic law; The carrier of cytoplasmic genetic material (organelles with DNA) has no mechanism of homogenization, but is random.

(4) When the nucleus is inherited, Reciprocal intersection Same. When cytoplasmic inheritance occurs, the traits of F1 are the same as those of the maternal parent, that is, maternal inheritance.

2. Mitochondria and chloroplasts are Semiautonomous organelle

Studies have found that in addition to DNA, there are RNA (mRNA, tRNA, rRNA) and ribosomes in mitochondria and chloroplasts. This indicates that both organelles have independent functions of transcription and translation, that is, mitochondria and chloroplasts have their own systems of transcription RNA and translation protein. But so far, it has been found that only 13 proteins can be synthesized by chloroplasts, and only more than 60 proteins can be synthesized by mitochondria, while thousands of proteins are involved in the formation of mitochondria and chloroplasts. This shows that mitochondria and chloroplasts encode themselves and synthesize few proteins, most of which are composed of Nuclear gene It is encoded and synthesized on the cytoplasm ribosome. In other words, the degree of autonomy of mitochondria and chloroplasts is limited, and they are highly dependent on the nuclear genetic system. Therefore, the growth and proliferation of mitochondria and chloroplasts are affected by Nuclear genome And its own genome, so they are called semi autonomous organelles.

effect

Announce

edit

The cytoplasm is the main place for metabolism, and the vast majority of chemical reactions are carried out in the cytoplasm. At the same time, it also has a regulatory effect on the nucleus.

Cytoplasm Cell plasma membrane The part inside and outside the nucleus. Homogeneous and translucent cytosol, organelles and Inclusion form. The cytosol accounts for about 1/2 of the cell volume and contains inorganic ions (such as K+, Mg2+, Ca2+, etc.), lipids, sugars, amino acids, proteins (including enzymes and proteins that constitute the cytoskeleton), etc. Skeletal protein It is closely related to cell morphology and movement, and is considered to have a significant effect on Enzyme reaction It provides a favorable framework structure. Most substances Intermediate metabolism (e.g. glycolysis, amino acids, fatty acids and nucleotide Metabolism) and the modification of some proteins (such as Phosphorylation ）It is carried out in cytosol. The organelles suspended in the cytosol, with and without boundary membrane, are involved in many kinds of cells Metabolic pathway 。 Inclusion It is the product formed in the process of cell life metabolism, such as Glycogen , pigment granules, fat drops, etc.

History of cytoplasmic research

Announce

edit

1665 Robert Hook, an Englishman, observed the thin slices of cork (oak bark) with a microscope designed and manufactured by himself (magnification: 40-140 times, Fig. 1-1), and described for the first time plant cell And used the Latin word cell for the first time to refer to the tiny closed cell similar to a beehive that he saw (in fact, only fibrous cell wall )。

16721682 Nehemaih Grew, an Englishman, published two volumes of microscopic atlases of plants and noticed the difference between cell wall and cytoplasm in plant cells.

1846 German H Von Mohl studied plants Protoplasm , published "identifies protoplast as the distance of cells".

1865 German J Von Suchs found chloroplasts.

1868 British T H. Huxley is Edinburgh The concept of protoplasm was introduced to the British public for the first time in a speech entitled "the physical basis of life".

1882 German E Strasburger proposed that cytoplasm and Nucleoplasm (nucleoplasm).

1898 Italian C Golgi observed Golgi apparatus with silver staining method.

In the 1950s, some people saw the existence of particles in chloroplasts that showed Fulgen reaction, and speculated that there might be DNA in them.

In 1962, Ris and Plant were observed by electron microscope chlamydomonas , chloroplasts of corn and other plants Ultrathin section , found in the matrix electron density The lower part has about 20.5 nm fine fibers use DNase It disappears during processing, proving it is DNA^[2] 。

Novice on the road

Growth task Getting Started with Editing Edit Rule Edit by myself

I have questions

Content query Online Service Official post bar Feedback

Complaints and suggestions

Report bad information Failed to appeal through entries Complaint of infringement information Blocking query and unblocking

Jinggong Network Anbei No. 1100000200001