What cytoplasm?What is its structure and composition?What are the functions it performs?In this article, we will answer all these questions.In addition, we will look at the structural features of the cytoplasm and its properties, as well as talk about the division of the colloidal solution, the structure of cell membranes and cell organelles important.
structural units of all tissue and organ cells.Two types of structural organization
known that the cells form a tissue of all animals and plants.These structural unit of all living things vary in shape, size and even the internal structure.But at the same time they have similar principles in life processes, including metabolism, growth and development, irritability and variability.The simplest forms of life consist of single cells and reproduce by dividing.
Scientists have identified two types of organization of the cell structure:
- prokaryotic;
- eukaryotic.
They have many differences in their structure.The prokaryotic cell nucleus is not structured.Its sole chromosome stored directly in the cytoplasm, that is not separated from the other elements.Such a structure is typical of bacteria.Their cytoplasm is poor in the composition of structures, but there are small ribosome.Eukaryotic arranged much more difficult prokaryotic cells.Her DNA is associated with proteins, located in the chromosomes, which are located in a separate cell organelles - nucleus.It is separated from other cell organelles porous membrane and is composed of elements such as chromatin and the nuclear sap nucleolus.Nevertheless, there is something in common in the two types of cellular organization.And prokaryotes and eukaryotes have a shell.And their internal contents presented a special colloidal solution in which there are various organelles and on-time.
eukaryotic cell: the cytoplasm.Its composition and functions
So, go to the heart of our research.What is the cytoplasm?Let's look at this in more detail the formation of the cell.The cytoplasm is a paramount component of cells located between the nucleus and the plasma membrane.Semi-fluid, it is riddled with tubules, microtubules, microfilaments and filaments.Also under the cytoplasm can be understood colloidal solution which is characterized by the movement of the colloidal particles, and other components.In this semi-medium consisting of water and various organic and inorganic compounds, arranged cell structures, organelles, and the ON time.The most important features are the cytoplasm.It carries out registration of all cellular components in a single system.Due to the cytoplasmic microtubules tubules and acts as a cellular skeleton and provides an environment for physiological and biochemical processes.In addition, it provides an opportunity for the functioning of all cell organelles and provides movement.These functions of the cell cytoplasm is extremely important, as they allow a structural unit of all living things carry out their normal activities.Now you know what the cytoplasm.Also aware of what position in the cell and what it takes "work" performs.Next we consider the composition and structure of the colloidal solution in more detail.
Are there any differences in the cytoplasm of plant and animal cells?
membrane organelles located in a colloidal solution, are considered to be the Golgi apparatus, endoplasmic reticulum, mitochondria, lysosomes, and the plastid outer cytoplasmic membrane.In the cells of animals and plants part of semi-environment differs.The cytoplasm of the plant cell has special organelles - the plastids.They are protein-specific cells that differ in function, shape and coloring pigments of various colors.Plastids are located in the cytoplasm and are able to move along with it.They grow, multiply and produce organic compounds containing enzymes.The cytoplasm of the plant cell has three types of plastids.Yellowish or orange called chromoplasts, green - chloroplasts and colorless - leucoplasts.There is another feature - the Golgi complex represented dictyosome scattered in the cytoplasm.In animal cells, in contrast to the plant, there are two layers of the cytoplasm.Outer called ectoplasm, and the inner - endoplasma.The first layer is adjacent to the cell membrane, and the second - between them is porous nuclear membrane.Ectoplasm is composed of a large number of microfilaments - strands of the globular protein actin molecules.Endoplasm contains various organelles, granules, characterized by a lower viscosity.
Hyaloplasm in eukaryotic cell cytoplasm
basis of so-called eukaryotes hyaloplasm.It is a slimy, colorless, non-homogeneous solution which is constantly flowing metabolism.Hyaloplasm (ie the matrix) is a colloidal system with a complex structure.Its structure includes RNA and soluble proteins, lipids and polysaccharides.In yet hyaloplasm contains large amounts of nucleotides, amino acids, inorganic ions and compounds such as Na- or Ca 2+ .Matriks does not have a homogeneous structure.It is presented in two forms, called a gel (solid) and the sol (liquid).Between them intertransitions occur.In the liquid phase has a system of subtle protein filaments called mikrotrabekulami.They link all the structures within the cell.And in places where they are crossing a group of ribosomes.Mikrotrabekuly with microtubules and microfilaments form a cytoplasmic skeleton.It defines and regulates the location of the cell organelles.
organic and inorganic substances in a colloidal solution cells
Let's look at what is the chemical composition of the cytoplasm?Substances contained in the cell can be classified into two groups - organic and inorganic.First presented in proteins, carbohydrates, fats and nucleic acids.Carbohydrates are presented in the cytoplasm of mono-, di- and polysaccharides.By monosaccharides, colorless crystals, usually sweet taste include fructose, glucose, ribose and the like. D. Large molecules composed of polysaccharides monosaccharides.In the cell, they are represented by starch, glycogen and cellulose.Lipids, i.e. fat molecules, radicals formed glycerol and fatty acids.The structure of the cytoplasm: inorganics are presented primarily water, which usually amounts to 90% by weight.It performs important functions in the cytoplasm.Water is the universal solvent, gives elasticity, is directly involved in the movement of materials, both within and between cells.Regarding macro forming the basis of biopolymers, more than 98% of the total composition occupied by cytoplasmic oxygen, hydrogen, carbon and nitrogen.Besides them, the cell contains sodium, calcium, sulfur, magnesium, chlorine and others. The mineral salts are present as anions and cations, with their ratio determined by acidity.
properties of the colloidal solution in the cell
consider further what are the main features of the cytoplasm.Firstly, it is a constant cyclosis.It represents the movement of intracellular cytoplasm.For the first time it was recorded and described in the 18th century Italian scientist court.Cyclosis carried out throughout the cytoplasm, including in the strands that connect the cytoplasm to the nucleus.If the motion for any reason ceases - die eukaryotic cell.The cytoplasm is necessarily in constant cyclosis, which is found on the movement of organelles.The velocity of the matrix depends on various factors, including the light and the temperature.For example, in the epidermis of onion scales cyclosis speed is about 6 m / s.The movement of the cytoplasm in the plant body has a huge impact on its growth and development, contributing to the transport of substances between cells.Another important property is the viscosity of the colloidal solution.It varies greatly depending on the type of organism.Some beings viscosity of the cytoplasm may be only slightly higher than the viscosity of water, while others, on the contrary, to achieve the viscosity of glycerin.It is believed that it is dependent on metabolism.The intensive exchange occurs, the lower the viscosity of the colloidal solution.Another important feature is semipermeable.Cytoplasmic in its composition has border membrane.They are due to a special in structure, have the ability to selectively pass molecules of some substances and not to let other.Selective permeability cytoplasm plays an important role in the process of life.It is not constant during the life varies with age and increases in plant organisms by increasing light intensity and temperature.It is difficult to overestimate the importance of the cytoplasm.She is involved in energy metabolism, transport of nutrients, excretion exotoxins.Also considered osmotic barrier matrix and is involved in the regulation of development, growth and cell division.Including cytoplasm plays an important role in DNA replication.
Features cell division
All plant and animal cells multiply by dividing.There are three known types - indirect, direct and pressure reducing.The first is also called amitosis.Indirect reproduction is as follows.Initially, "pereshnurovyvaetsya" core, and then there is a division of the cytoplasm.As a result, two cells are formed that gradually grow to the size of the parent.This kind of division in animals is extremely rare.Typically, they occur indirect division, ie mitosis.It is much more difficult amitosis and is characterized by the fact that there is a strengthening in the core synthesis and doubling the amount of DNA.Mitosis has four phases, which are called - prophase, metaphase, anaphase and telophase.
- first phase is characterized by the formation of the tangle of chromatin strands at the nucleus, chromosomes and subsequently as a "stud".In this period there is a discrepancy of centrioles to the poles and the formation achromatin spindle.
- second stage of mitosis characterized in that chromosome, reaching a maximum coiling begin located at the equator cells orderly.
- In the third phase is split into two chromatids of a chromosome.This spindle fibers contract and pulled daughter chromosomes to opposite poles.
- In the fourth phase of mitosis occurs dispiralizatsiya chromosomes, as well as the formation of the nuclear envelope around them.Simultaneously, the division of the cytoplasm.We daughter cell has a diploid set of chromosomes.
reduction division peculiar to the sexual cells.In this type of cell division is the formation of chromosomes paired formations.The exception is one unpaired chromosome.As a result of reduction division in two daughter cells receive half of chromosome set.The median is only one daughter cell.Germ cells having half the number of chromosomes, mature and capable of fertilization, called female and male gametes.
concept of cytoplasmic membrane
All cells of animals, plants and even the simplest bacteria have a special surface unit that limits and protects the matrix from the environment.Cytoplasmic membrane (plasmalemma, the cell membrane, plasma membrane) is a selectively permeable layer of molecules (proteins, phospholipids), which covers the cytoplasm.It consists of three subsystems:
- plasma membrane;
- nadmembranny complex;
- submembranny support-contractile apparatus hyaloplasm.
cytoplasmic membrane structure is as follows: it comprises two layers of lipid molecules (bilayer), each such molecule has a tail and a head.Tails are facing each other.They are hydrophobic.Hydrophilic head and face inwardly and outwardly of the cell.The bilayer includes a protein molecule.Moreover, it is asymmetrical and are located in different lipid monolayers.For example, in a eukaryotic cell cholesterol molecules are found in the inner, adjacent to the cytoplasm, membrane half.Glycolipids located only in the outer layer, and their carbohydrate chains are always directed outward.The cytoplasmic membrane performs critical functions, including limits internal contents of the cell from the external environment, allows it to penetrate certain substances (glucose, amino acids) into cells.Plasmalemma provides transport of substances into the cell, as well as bringing out, then there is a selection.Through the pores penetrating water, ions and small molecule compounds, and coarse particles are transported into the cell by means of phagocytosis.On the surface membrane forms microvilli, invaginations and protrusions, which not only effectively absorb and release substances, and communicate with other cells.The membrane allows attachment of "unity of all living things" to different surfaces and facilitates movement.
organelles in the cytoplasm of the composition.Endoplasmic reticulum and ribosomes
hyaloplasm addition, the cytoplasm contains a set of microscopic organelles and that differ in structure.Their presence in plant and animal cells suggests that they perform essential functions and vital.To some extent, these morphological education comparable to the organs of the body of man or animal, which gave the opportunity to call their organelles.In the cytoplasm distinction visible in the light microscope a platelet organelles complex, mitochondria, and the centrosome.Using electron microscopy revealed a matrix of microtubules, lysosomes, ribosomes and plasma network.The cytoplasm of the cell is riddled with different channels, which are called "endpolazmaticheskaya network."Their membrane walls in contact with all other organelles, and constitute a single system that performs energy metabolism, as well as the movement of substances within the cell.The walls of these channels are the ribosomes, which look like tiny beads.They can be placed singly or in groups.Ribosomes consist of almost equal amounts of RNA and protein.Also included in the composition of their magnesium.Ribosomes can not only be in the channels of the EPS, and free to be in the cytoplasm, as well as to meet in the nucleus, where they are formed.The set of channels having ribosomes are called granular endoplasmic reticulum.They except ribosomes located enzymes, facilitate the synthesis of carbohydrates and fats.The internal cavities of the channels are the waste products of cells.Sometimes extensions EPS formed vacuoles - of the cavity filled with juice and limited cellular membrane.These organelles maintain turgor pressure.Lysosomes are small oval-shaped formation.They are scattered throughout the cytoplasm.Lysosomes formed in EPS or the Golgi complex, where filled with hydrolytic enzymes.Lysosomes are designed to digest particles inside cells as a result of phagocytosis.
cytoplasm: the structure and function of its organelles.Plate Golgi complex, mitochondria centrosome and Golgi complex
presented in plant cells by individual calves decorated membranes, and in animals - tubules, vesicles and cisterns.This organelle is designed for chemical changes, compaction and subsequent withdrawal of the cytoplasm of the cell product secretion.It also carried out the synthesis of polysaccharides and glycoproteins education.Mitochondria - the calf is rod-shaped, filamentous or granular form.They are limited to two membranes, which consist of a bilayer of phospholipids and proteins.From the internal membranes of these organelles depart cristae, the walls of which are enzymes.With their help, the synthesis of adenosine triphosphate (ATP).Mitochondria are sometimes called "cellular power plants" because they deliver a significant part of adenosine triphosphate.It is used by the cell as a source of chemical energy.Moreover, mitochondria and perform other functions, including signal transduction, cell death, cell differentiation.Centrosome (the cell center) is composed of two centrioles, which are arranged at an angle to each other.
