Cell (biology)
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www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=Cell+Movements+and+the+Shaping+of+the+Vertebrate+Body+AND+mboc4%5Bbook%5D+AND+374635%5Buid%5D&rid=mboc4.section.3919 Cell Movements and the Shaping of the Vertebrate Body] in Chapter 21 of Molecular Biology of the Cell fourth edition, edited by Bruce Alberts (2002) published by Garland Science.
The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as amino acids as "molecular building blocks".</ref> Some organisms, such as bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular. (Humans have an estimated 100 trillion or 1014 cells; a typical cell size is 10 µm; a typical cell mass is 1 nanogram.) The largest known cell is an ostrich egg.//www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=Cell+Movements+and+the+Shaping+of+the+Vertebrate+Body+AND+mboc4%5Bbook%5D+AND+374635%5Buid%5D&rid=mboc4.section.3919 Cell Movements and the Shaping of the Vertebrate Body] in Chapter 21 of Molecular Biology of the Cell fourth edition, edited by Bruce Alberts (2002) published by Garland Science.
The Alberts text discusses how the "cellular building blocks" move to shape developing embryos. It is also common to describe small molecules such as amino acids as "molecular building blocks".</ref> Some organisms, such as bacteria, are unicellular (consist of a single cell). Other organisms, such as humans, are multicellular. (Humans have an estimated 100 trillion or 1014 cells; a typical cell size is 10 µm; a typical cell mass is 1 nanogram.) The largest known cell is an ostrich egg.
In 1837 before the final cell theory was developed, a Czech Jan Evangelista Purkyňe observed small "granules" while looking at the plant tissue through a microscope.
The cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells. All cells come from preexisting cells. Vital functions of an organism occur within cells, and all cells contain the hereditary information necessary for regulating cell functions and for transmitting information to the next generation of cells.
www.ucmp.berkeley.edu/history/hooke.html Robert Hooke]</ref>//www.ucmp.berkeley.edu/history/hooke.html Robert Hooke]</ref>
Sommaire[masquer] |
Preamble
Each cell is at least somewhat self-contained and self-maintaining: it can take in nutrients, convert these nutrients into energy, carry out specialized functions, and reproduce as necessary. Each cell stores its own set of instructions for carrying out each of these activities.
www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=%22all+cells%22+AND+mboc4%5Bbook%5D+AND+372023%5Buid%5D&rid=mboc4.section.4#23 The Universal Features of Cells on Earth] in Chapter 1 of the Alberts textbook (reference #1, above).</ref>//www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=%22all+cells%22+AND+mboc4%5Bbook%5D+AND+372023%5Buid%5D&rid=mboc4.section.4#23 The Universal Features of Cells on Earth] in Chapter 1 of the Alberts textbook (reference #1, above).</ref>
- Reproduction by cell division: (binary fission/mitosis or meiosis).
- Use of enzymes and other proteins coded for by DNA genes and made via messenger RNA intermediates and ribosomes.
- Metabolism, including taking in raw materials, building cell components, converting energy, molecules and releasing by-products. The functioning of a cell depends upon its ability to extract and use chemical energy stored in organic molecules. This energy is derived from metabolic pathways.
- Response to external and internal stimuli such as changes in temperature, pH or nutrient levels.
- Cell contents are contained within a cell surface membrane that contains proteins and a lipid bilayer.
dx.doi.org/10.1111/j.1365-2958.2006.05272.x}}</ref> but eukaryotic cells have a highly specialized endomembrane system characterized by regulated traffic and transport of vesicles.<ref name="Rose2005">A. Rose, S. J. Schraegle, E. A. Stahlberg and I. Meier (2005) "Coiled-coil protein composition of 22 proteomes--differences and common themes in subcellular infrastructure and traffic control" in BMC evolutionary biology Vulume 5 article 66. Modèle:Entrez Pubmed
Rose et al. suggest that coiled-coil alpha helical vesicle transport proteins are only found in eukaryotic organisms.</ref>//dx.doi.org/10.1111/j.1365-2958.2006.05272.x}}</ref> but eukaryotic cells have a highly specialized endomembrane system characterized by regulated traffic and transport of vesicles.<ref name="Rose2005">A. Rose, S. J. Schraegle, E. A. Stahlberg and I. Meier (2005) "Coiled-coil protein composition of 22 proteomes--differences and common themes in subcellular infrastructure and traffic control" in BMC evolutionary biology Vulume 5 article 66. Modèle:Entrez Pubmed
Rose et al. suggest that coiled-coil alpha helical vesicle transport proteins are only found in eukaryotic organisms.</ref>
Anatomy of cells
There are two types of cells: eukaryotic and prokaryotic. Prokaryotic cells are usually independent, while eukaryotic cells are usually found in multicellular organisms.
Prokaryotic cells
Prokaryotes are distinguished from eukaryotes on the basis of nuclear organization, specifically their lack of a nuclear membrane. Prokaryotes also lack most of the intracellular organelles and structures that are characteristic of eukaryotic cells (an important exception is the ribosome, which are present in both prokaryotic and eukaryotic cells). Most functions of organelles, such as mitochondria, chloroplasts, and the Golgi apparatus, are taken over by the prokaryotic plasma membrane. Prokaryotic cells have three architectural regions: appendages called flagella and pili — proteins attached to the cell surface; a cell envelope consisting of a capsule, a cell wall, and a plasma membrane; and a cytoplasmic region that contains the cell genome (DNA) and ribosomes and various sorts of inclusions. Other differences include:
- The plasma membrane (a phospholipid bilayer) separates the interior of the cell from its environment and serves as a filter and communications beacon.
- Most prokaryotes have a cell wall (some exceptions are Mycoplasma (a bacterium) and Thermoplasma (an archaeon)). It consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces. It also prevents the cell from "exploding" (cytolysis) from osmotic pressure against a hypotonic environment. A cell wall is also present in some eukaryotes like plants (cellulose) and fungi, but has a different chemical composition.
- A prokaryotic chromosome is usually a circular molecule (an exception is that of the bacterium Borrelia burgdorferi, which causes Lyme disease). Even without a real nucleus, the DNA is condensed in a nucleoid. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular. Plasmids can carry additional functions, such as antibiotic resistance.
Eukaryotic cells
Eukaryotic cells are about 10 times the size of a typical prokaryote and can be as much as 1000 times greater in volume. The major difference between prokaryotes and eukaryotes is that eukaryotic cells contain membrane-bound compartments in which specific metabolic activities take place. Most important among these is the presence of a cell nucleus, a membrane-delineated compartment that houses the eukaryotic cell's DNA. It is this nucleus that gives the eukaryote its name, which means "true nucleus". Other differences include:
- The plasma membrane resembles that of prokaryotes in function, with minor differences in the setup. Cell walls may or may not be present.
- The eukaryotic DNA is organized in one or more linear molecules, called chromosomes, which are associated with histone proteins. All chromosomal DNA is stored in the cell nucleus, separated from the cytoplasm by a membrane. Some eukaryotic organelles also contain some DNA.
- Eukaryotes can move using cilia or flagella. The flagella are more complex than those of prokaryotes.
| Prokaryotes | Eukaryotes | |
|---|---|---|
| Typical organisms | bacteria, archaea | protists, fungi, plants, animals |
| Typical size | ~ 1-10 µm | ~ 10-100 µm (sperm cells, apart from the tail, are smaller) |
| Type of nucleus | nucleoid region; no real nucleus | real nucleus with double membrane |
| DNA | circular (usually) | linear molecules (chromosomes) with histone proteins |
| RNA-/protein-synthesis | coupled in cytoplasm | RNA-synthesis inside the nucleus protein synthesis in cytoplasm |
| Ribosomes | 50S+30S | 60S+40S |
| Cytoplasmatic structure | very few structures | highly structured by endomembranes and a cytoskeleton |
| Cell movement | flagella made of flagellin | flagella and cilia made of tubulin, lamellipodia |
| Mitochondria | none | one to several thousand (though some lack mitochondria) |
| Chloroplasts | none | in algae and plants |
| Organization | usually single cells | single cells, colonies, higher multicellular organisms with specialized cells |
| Cell division | Binary fission (simple division) | Mitosis (fission or budding) Meiosis |
| Typical animal cell | Typical plant cell | |
|---|---|---|
| Organelles |
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| Additional structures |
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Subcellular components
All cells, whether prokaryotic or eukaryotic, have a membrane that envelops the cell, separates its interior from its environment, regulates what moves in and out (selectively permeable), and maintains the electric potential of the cell. Inside the membrane, a salty cytoplasm takes up most of the cell volume. All cells possess DNA, the hereditary material of genes, and RNA, containing the information necessary to build various proteins such as enzymes, the cell's primary machinery. There are also other kinds of biomolecules in cells. This article will list these primary components of the cell, then briefly describe their function.
Cell membrane: A cell's defining boundary
The cytoplasm of a cell is surrounded by a plasma membrane. The plasma membrane in plants and prokaryotes is usually covered by a cell wall. This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of lipids (hydrophobic fat-like molecules) and hydrophilic phosphorus molecules. Hence, the layer is called a phospholipid bilayer. It may also be called a fluid mosaic membrane. Embedded within this membrane is a variety of protein molecules that act as channels and pumps that move different molecules into and out of the cell. The membrane is said to be 'semi-permeable', in that it can either let a substance (molecule or ion) pass through freely, pass through to a limited extent or not pass through at all. Cell surface membranes also contain receptor proteins that allow cells to detect external signalling molecules such as hormones.
Cytoskeleton: A cell's scaffold
The cytoskeleton acts to organize and maintain the cell's shape; anchors organelles in place; helps during endocytosis, the uptake of external materials by a cell, and cytokinesis, the separation of daughter cells after cell division; and moves parts of the cell in processes of growth and mobility. The eukaryotic cytoskeleton is composed of microfilaments, intermediate filaments and microtubules. There is a great number of proteins associated with them, each controlling a cell's structure by directing, bundling, and aligning filaments. The prokaryotic cytoskeleton is less well-studied but is involved in the maintenance of cell shape, polarity and cytokinesis.<ref>Modèle:Cite journal</ref>
Genetic material
Two different kinds of genetic material exist: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Most organisms use DNA for their long-term information storage, but some viruses (e.g., retroviruses) have RNA as their genetic material. The biological information contained in an organism is encoded in its DNA or RNA sequence. RNA is also used for information transport (e.g., mRNA) and enzymatic functions (e.g., ribosomal RNA) in organisms that use DNA for the genetic code itself.
Prokaryotic genetic material is organized in a simple circular DNA molecule (the bacterial chromosome) in the nucleoid region of the cytoplasm. Eukaryotic genetic material is divided into different, linear molecules called chromosomes inside a discrete nucleus, usually with additional genetic material in some organelles like mitochondria and chloroplasts (see endosymbiotic theory).
A human cell has genetic material in the nucleus (the nuclear genome) and in the mitochondria (the mitochondrial genome). In humans the nuclear genome is divided into 46 linear DNA molecules called chromosomes. The mitochondrial genome is a circular DNA molecule separate from the nuclear DNA. Although the mitochondrial genome is very small, it codes for some important proteins.
Foreign genetic material (most commonly DNA) can also be artificially introduced into the cell by a process called transfection. This can be transient, if the DNA is not inserted into the cell's genome, or stable, if it is.
Organelles
The human body contains many different organs, such as the heart, lung, and kidney, with each organ performing a different function. Cells also have a set of "little organs," called organelles, that are adapted and/or specialized for carrying out one or more vital functions. Membrane-bound organelles are found only in eukaryotes.
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| Image:Endomembrane system diagram no text nucleus.png |
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[modifier] Cell functions[modifier] Cell growth and metabolismBetween successive cell divisions, cells grow through the functioning of cellular metabolism. Cell metabolism is the process by which individual cells process nutrient molecules. Metabolism has two distinct divisions: catabolism, in which the cell breaks down complex molecules to produce energy and reducing power, and anabolism, in which the cell uses energy and reducing power to construct complex molecules and perform other biological functions. Complex sugars consumed by the organism can be broken down into a less chemically-complex sugar molecule called glucose. Once inside the cell, glucose is broken down to make adenosine triphosphate (ATP), a form of energy, via two different pathways. The first pathway, glycolysis, requires no oxygen and is referred to as anaerobic metabolism. Each reaction is designed to produce some hydrogen ions that can then be used to make energy packets (ATP). In prokaryotes, glycolysis is the only method used for converting energy. The second pathway, called the Krebs cycle, or citric acid cycle, occurs inside the mitochondria and is capable of generating enough ATP to run all the cell functions. Image:Proteinsynthesis.png An overview of protein synthesis. Within the nucleus of the cell (light blue), genes (DNA, dark blue) are transcribed into RNA. This RNA is then subject to post-transcriptional modification and control, resulting in a mature mRNA (red) that is then transported out of the nucleus and into the cytoplasm (peach), where it undergoes translation into a protein. mRNA is translated by ribosomes (purple) that match the three-base codons of the mRNA to the three-base anti-codons of the appropriate tRNA. Newly-synthesized proteins (black) are often further modified, such as by binding to an effector molecule (orange), to become fully active. [modifier] Creation of new cellsCell division involves a single cell (called a mother cell) dividing into two daughter cells. This leads to growth in multicellular organisms (the growth of tissue) and to procreation (vegetative reproduction) in unicellular organisms. Prokaryotic cells divide by binary fission. Eukaryotic cells usually undergo a process of nuclear division, called mitosis, followed by division of the cell, called cytokinesis. A diploid cell may also undergo meiosis to produce haploid cells, usually four. Haploid cells serve as gametes in multicellular organisms, fusing to form new diploid cells. DNA replication, or the process of duplicating a cell's genome, is required every time a cell divides. Replication, like all cellular activities, requires specialized proteins for carrying out the job. [modifier] Protein synthesisCells are capable of synthesizing new proteins, which are essential for the modulation and maintenance of cellular activities. This process involves the formation of new protein molecules from amino acid building blocks based on information encoded in DNA/RNA. Protein synthesis generally consists of two major steps: transcription and translation. Transcription is the process where genetic information in DNA is used to produce a complementary RNA strand. This RNA strand is then processed to give messenger RNA (mRNA), which is free to migrate through the cell. mRNA molecules bind to protein-RNA complexes called ribosomes located in the cytosol, where they are translated into polypeptide sequences. The ribosome mediates the formation of a polypeptide sequence based on the mRNA sequence. The mRNA sequence directly relates to the polypeptide sequence by binding to transfer RNA (tRNA) adapter molecules in binding pockets within the ribosome. The new polypeptide then folds into a functional three-dimensional protein molecule. [modifier] Cell movement or motilityCell has the ability to move spontaneously during the process of wound healing, immune response and cancer metastasis. The fastest moving cells in the human body are the spermaculi, which enter and exit through the penis. This was proven when Professor Julia Ertmann of UCLA observed changes in the reproductive spermaculi in a lab environment (circa 2005). www.biolsci.org/v03p0303.htm</reF> The process is divided into three steps - protrusion of the leading edge of the cell, adhesion of the leading edge and deadhesion at the cell body and rear, and cytoskeletal contraction to pull the cell forward. Each of these steps is driven by physical forces generated by unique segments of the cytoskeleton. <ref name="AlbertsB">Alberts B, Johnson A, Lewis J. et al. Molecular Biology of the Cell, 4e. Garland Science. 2002</ref><ref name="Ananthakrishnan">Ananthakrishnan R, Ehrlicher A. The Forces Behind Cell Movement. Int J Biol Sci 2007; 3:303-317. http://www.biolsci.org/v03p0303.htm</ref>//www.biolsci.org/v03p0303.htm</reF> The process is divided into three steps - protrusion of the leading edge of the cell, adhesion of the leading edge and deadhesion at the cell body and rear, and cytoskeletal contraction to pull the cell forward. Each of these steps is driven by physical forces generated by unique segments of the cytoskeleton. <ref name="AlbertsB">Alberts B, Johnson A, Lewis J. et al. Molecular Biology of the Cell, 4e. Garland Science. 2002</ref><ref name="Ananthakrishnan">Ananthakrishnan R, Ehrlicher A. The Forces Behind Cell Movement. Int J Biol Sci 2007; 3:303-317. http://www.biolsci.org/v03p0303.htm</ref> [modifier] Origins of cellsThe origin of cells has to do with the origin of life, and is one of the most important steps in the theory of evolution. The birth of the cell marked the passage from prebiotic chemistry to biological life. [modifier] Origin of the first cell
In a gene-centered view of evolution, life is regarded in terms of replicators—that is DNA molecules in the organism. In this paradigm, cells satisfy two fundamental conditions: protection from the outside environment and confinement of biochemical activity. The former condition is needed to maintain the stability of fragile DNA chains in a varying and sometimes aggressive environment, and may have been the main reason for which cells evolved. The latter is fundamental for the evolution of complexity. If freely-floating DNA molecules that code for enzymes are not enclosed in cells, the enzymes that benefit a given replicator (for example, by producing nucleotides) may do so less efficiently, and may in fact benefit competing replicators. If the entire DNA molecule of a replicator is enclosed in a cell, then the enzymes coded from the molecule will be kept close to the DNA molecule itself. The replicator will directly benefit from its encoded enzymes. users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Phospholipids.html</ref>//users.rcn.com/jkimball.ma.ultranet/BiologyPages/P/Phospholipids.html</ref> [modifier] Origin of eukaryotic cellsThe eukaryotic cell seems to have evolved from a symbiotic community of prokaryotic cells. It is almost certain that DNA-bearing organelles like the mitochondria and the chloroplasts are what remains of ancient symbiotic oxygen-breathing proteobacteria and cyanobacteria, respectively, where the rest of the cell seems to be derived from an ancestral archaean prokaryote cell – a theory termed the endosymbiotic theory. There is still considerable debate about whether organelles like the hydrogenosome predated the origin of mitochondria, or viceversa: see the hydrogen hypothesis for the origin of eukaryotic cells. Sex, as the stereotyped choreography of meiosis and syngamy that persists in nearly all extant eukaryotes, may have played a role in the transition from prokaryotes to eukaryotes. An 'origin of sex as vaccination' theory suggests that the eukaryote genome accreted from prokaryan parasite genomes in numerous rounds of lateral gene transfer. Sex-as-syngamy (fusion sex) arose when infected hosts began swapping nuclearized genomes containing coevolved, vertically transmitted symbionts that conveyed protection against horizontal infection by more virulent symbionts.<ref name="sterrer">Modèle:Cite journal</ref> [modifier] History
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[modifier] External linksModèle:Wikibookspar www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells. www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.studiodaily.com/main/searchlist/6850.html The Inner Life of A Cell], a flash video showing what happens inside of a cell www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.ibiblio.org/virtualcell/tour/cell/cell.htm The Virtual Cell] www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.cellsalive.com/ Cells Alive!] www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.jcb.org/ Journal of Cell Biology] www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//members.optusnet.com.au/exponentialist/Cells.htm A comparison of the generational and exponential growth of cell populations] www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//brainmaps.org/index.php?q=cell High-resolution images of brain cells] www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.biology.arizona.edu/cell_bio/cell_bio.html The Biology Project > Cell Biology] www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//cellimages.ascb.org/ The Image & Video Library] of The American Society for Cell Biology, a collection of peer-reviewed still images, video clips and digital books that illustrate the structure, function and biology of the cell. www.ixedu.com/es/celula/Introduccion.html Ixedu.com] 3D Animations, Virtual Microscope, Activities, a Game and more! All about the cells.//www.centreofthecell.org/ Centre of the Cell online] [modifier] Online textbookswww.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.TOC&depth=2 | isbn = 0815332181}}//www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mboc4.TOC&depth=2 | isbn = 0815332181}} www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.TOC | isbn = 978-0716743668}}//www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.TOC | isbn = 978-0716743668}} www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=cooper.TOC&depth=2 }}//www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=cooper.TOC&depth=2 }} cellimages.ascb.org/cdm4/browse.php?CISOROOT=/p4041coll11 Landmark Papers in Cell Biology]. Bethesda, MD and Cold Spring Harbor, NY: The American Society for Cell Biology and Cold Spring Harbor Laboratory Press; 2001. Commentaries and links to original research papers published in the ASCB Image & Video Library//cellimages.ascb.org/cdm4/browse.php?CISOROOT=/p4041coll11 Landmark Papers in Cell Biology]. Bethesda, MD and Cold Spring Harbor, NY: The American Society for Cell Biology and Cold Spring Harbor Laboratory Press; 2001. Commentaries and links to original research papers published in the ASCB Image & Video Library Modèle:Organelles Modèle:CompositionModèle:Link FA Modèle:Link FA ar:خلية bn:কোষ (জীববিজ্ঞান) zh-min-nan:Sè-pau bs:Ćelija br:Kellig bg:Клетка ca:Cèl·lula ceb:Cellule cs:Buňka cy:Cell (bioleg) da:Celle (biologi) de:Zelle (Biologie) et:Rakk el:Κύτταρο es:Célula eo:Biologia ĉelo eu:Zelula fa:یاخته fo:Kykna fr:Cellule (biologie) gl:Célula ko:세포 hi:कोशिका hr:Stanica io:Celulo id:Sel (Biologi) ia:Cellula (biologia) is:Fruma it:Cellula he:תא kn:ಜೀವ ಕಣ ka:უჯრედი ku:Şane la:Cellula lv:Šūna lt:Ląstelė jbo:ji'esle hu:Sejt mk:Клетка ms:Sel (biologi) nl:Cel (biologie) ja:細胞 no:Celle nn:Celle nrm:Aître oc:Cellula (biologia) pl:Komórka pt:Célula ro:Celulă qu:Kawsaykuq ru:Клетка sq:Qeliza si:සෛලය simple:Cell sk:Bunka sl:Celica sr:Ћелија (биологија) su:Sél (biologi) fi:Solu sv:Cell ta:கலம் te:జీవకణం th:เซลล์ (ชีววิทยา) vi:Tế bào tr:Hücre uk:Клітина ur:خلیہ yi:צעל zh-yue:細胞 zh:细胞 |
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