Cell (biology)

cellcellscellularbiological cellbiological cellssubcellularanimal cellscellular processcellular processesliving cells
The cell (from Latin cella, meaning "small room" ) is the basic structural, functional, and biological unit of all known living organisms.wikipedia
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Cytoplasm

cytoplasmiccytosolicintracytoplasmic
Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. Inside the cell is the cytoplasmic region that contains the genome (DNA), ribosomes and various sorts of inclusions. The genetic material is freely found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular. Linear bacterial plasmids have been identified in several species of spirochete bacteria, including members of the genus Borrelia notably Borrelia burgdorferi, which causes Lyme disease. Though not forming a nucleus, the DNA is condensed in a nucleoid. Plasmids encode additional genes, such as antibiotic resistance genes.
In cell biology, the cytoplasm is all of the material within a cell, enclosed by the cell membrane, except for the cell nucleus.

Life

livinglife on Earthbiota
A cell is the smallest unit of life. Prokaryotic cells were the first form of life on Earth, characterised by having vital biological processes including cell signaling.
One popular definition is that organisms are open systems that maintain homeostasis, are composed of cells, have a life cycle, undergo metabolism, can grow, adapt to their environment, respond to stimuli, reproduce and evolve.

Protein

proteinsprotein synthesisproteinaceous
Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.
Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms and participate in virtually every process within cells.

Cell theory

steady-state membrane pump
Cell theory, first developed in 1839 by Matthias Jakob Schleiden and Theodor Schwann, states that all organisms are composed of one or more cells, that cells are the fundamental unit of structure and function in all living organisms, and that all cells come from pre-existing cells.
In biology, cell theory is the historic scientific theory, now universally accepted, that living organisms are made up of cells, that they are the basic structural/organizational unit of all organisms, and that all cells come from pre-existing cells.

Cell nucleus

nucleusnucleinuclear
Cells are of two types: eukaryotic, which contain a nucleus, and prokaryotic, which do not. They are simpler and smaller than eukaryotic cells, and lack membrane-bound organelles such as a nucleus.
nuclei; from Latin nucleus or nuculeus, meaning kernel or seed) is a membrane-enclosed organelle found in eukaryotic cells.

Multicellular organism

multicellularmulticellular organismsmulticellularity
Organisms can be classified as unicellular (consisting of a single cell; including bacteria) or multicellular (including plants and animals).
Multicellular organisms are organisms that consist of more than one cell, in contrast to unicellular organisms.

Cell signaling

cell signallingsignallingsignaling pathway
Prokaryotic cells were the first form of life on Earth, characterised by having vital biological processes including cell signaling.
Cell signaling (cell signalling in British English) is part of any communication process that governs basic activities of cells and coordinates all cell actions.

Cell wall

cell wallsplant cell wallprimary cell wall
Enclosing the cell is the cell envelope – generally consisting of a plasma membrane covered by a cell wall which, for some bacteria, may be further covered by a third layer called a capsule. Though most prokaryotes have both a cell membrane and a cell wall, there are exceptions such as Mycoplasma (bacteria) and Thermoplasma (archaea) which only possess the cell membrane layer. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, serving as a protective filter. The cell wall consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces. It also prevents the cell from expanding and bursting (cytolysis) from osmotic pressure due to a hypotonic environment. Some eukaryotic cells (plant cells and fungal cells) also have a cell wall.
A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane.

Three-domain system

three domainsdomainsthree domains of life
Prokaryotes include bacteria and archaea, two of the three domains of life.
The three-domain system is a biological classification introduced by Carl Woese et al. in 1977 that divides cellular life forms into archaea, bacteria, and eukaryote domains.

Cell membrane

plasma membranemembranecell membranes
Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids. Enclosing the cell is the cell envelope – generally consisting of a plasma membrane covered by a cell wall which, for some bacteria, may be further covered by a third layer called a capsule. Though most prokaryotes have both a cell membrane and a cell wall, there are exceptions such as Mycoplasma (bacteria) and Thermoplasma (archaea) which only possess the cell membrane layer. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, serving as a protective filter. The cell wall consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces. It also prevents the cell from expanding and bursting (cytolysis) from osmotic pressure due to a hypotonic environment. Some eukaryotic cells (plant cells and fungal cells) also have a cell wall.
The cell membrane (also known as the plasma membrane (PM) or cytoplasmic membrane, and historically referred to as the plasmalemma) is a biological membrane that separates the interior of all cells from the outside environment (the extracellular space) which protects the cell from its environment consisting of a lipid bilayer with embedded proteins.

Extrachromosomal DNA

extrachromosomalCircular DNAextrachromosomal elements
Inside the cell is the cytoplasmic region that contains the genome (DNA), ribosomes and various sorts of inclusions. The genetic material is freely found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular. Linear bacterial plasmids have been identified in several species of spirochete bacteria, including members of the genus Borrelia notably Borrelia burgdorferi, which causes Lyme disease. Though not forming a nucleus, the DNA is condensed in a nucleoid. Plasmids encode additional genes, such as antibiotic resistance genes.
Extrachromosomal DNA is any DNA that is found outside the nucleus of a cell.

Bacteria

bacteriumbacterialeubacteria
Organisms can be classified as unicellular (consisting of a single cell; including bacteria) or multicellular (including plants and animals). Prokaryotes include bacteria and archaea, two of the three domains of life.
Bacteria (common noun bacteria, singular bacterium) are a type of biological cell.

Organelle

organellescell organellescell organelle
They are simpler and smaller than eukaryotic cells, and lack membrane-bound organelles such as a nucleus.
In cell biology, an organelle is a specialized subunit within a cell that has a specific function.

Micrometre

µmμmmicrometers
Most plant and animal cells are visible only under a microscope, with dimensions between 1 and 100 micrometres.
The micrometre is a common unit of measurement for wavelengths of infrared radiation as well as sizes of biological cells and bacteria, and for grading wool by the diameter of the fibres.

Biological process

biological processesbiologicalprocess
Prokaryotic cells were the first form of life on Earth, characterised by having vital biological processes including cell signaling.
Organization: being structurally composed of one or more cells – the basic units of life

Ribosome

ribosomesribosomal70S
RNA is used for information transport (e.g., mRNA) and enzymatic functions (e.g., ribosomal RNA).
The ribosome is a complex molecular machine, found within all living cells, that serves as the site of biological protein synthesis (translation).

Nucleoid

genophorenucleoidsbacterial chromosome
Inside the cell is the cytoplasmic region that contains the genome (DNA), ribosomes and various sorts of inclusions. The genetic material is freely found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular. Linear bacterial plasmids have been identified in several species of spirochete bacteria, including members of the genus Borrelia notably Borrelia burgdorferi, which causes Lyme disease. Though not forming a nucleus, the DNA is condensed in a nucleoid. Plasmids encode additional genes, such as antibiotic resistance genes. The nuclear region in the cytoplasm is called the nucleoid.
The nucleoid (meaning nucleus-like) is an irregularly shaped region within the cell of a prokaryote that contains all or most of the genetic material, called genophore.

Cytoskeleton

cytoskeletalcytoskeletal proteinsactin cytoskeleton
Centrosome: the cytoskeleton organiser: The centrosome produces the microtubules of a cell – a key component of the cytoskeleton. It directs the transport through the ER and the Golgi apparatus. Centrosomes are composed of two centrioles, which separate during cell division and help in the formation of the mitotic spindle. A single centrosome is present in the animal cells. They are also found in some fungi and algae cells.
A cytoskeleton is present in the cytoplasm of all cells, including bacteria, and archaea.

Plasmid

plasmidsepisomeplasmid vector
Inside the cell is the cytoplasmic region that contains the genome (DNA), ribosomes and various sorts of inclusions. The genetic material is freely found in the cytoplasm. Prokaryotes can carry extrachromosomal DNA elements called plasmids, which are usually circular. Linear bacterial plasmids have been identified in several species of spirochete bacteria, including members of the genus Borrelia notably Borrelia burgdorferi, which causes Lyme disease. Though not forming a nucleus, the DNA is condensed in a nucleoid. Plasmids encode additional genes, such as antibiotic resistance genes.
The size of the plasmid varies from 1 to over 200 kbp, and the number of identical plasmids in a single cell can range anywhere from one to thousands under some circumstances.

Tonicity

hypertonicisotonichypotonic
Enclosing the cell is the cell envelope – generally consisting of a plasma membrane covered by a cell wall which, for some bacteria, may be further covered by a third layer called a capsule. Though most prokaryotes have both a cell membrane and a cell wall, there are exceptions such as Mycoplasma (bacteria) and Thermoplasma (archaea) which only possess the cell membrane layer. The envelope gives rigidity to the cell and separates the interior of the cell from its environment, serving as a protective filter. The cell wall consists of peptidoglycan in bacteria, and acts as an additional barrier against exterior forces. It also prevents the cell from expanding and bursting (cytolysis) from osmotic pressure due to a hypotonic environment. Some eukaryotic cells (plant cells and fungal cells) also have a cell wall.
It is commonly used when describing the response of cells immersed in an external solution.

Cell division

divisiondaughter cellcellular division
Centrosome: the cytoskeleton organiser: The centrosome produces the microtubules of a cell – a key component of the cytoskeleton. It directs the transport through the ER and the Golgi apparatus. Centrosomes are composed of two centrioles, which separate during cell division and help in the formation of the mitotic spindle. A single centrosome is present in the animal cells. They are also found in some fungi and algae cells. 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.
Cell division is the process by which a parent cell divides into two or more daughter cells.

Biomolecule

biochemicalbiomoleculesbiomolecular
Cells consist of cytoplasm enclosed within a membrane, which contains many biomolecules such as proteins and nucleic acids.
They serve as sources of chemical energy (adenosine triphosphate and guanosine triphosphate), participate in cellular signaling (cyclic guanosine monophosphate and cyclic adenosine monophosphate), and are incorporated into important cofactors of enzymatic reactions (coenzyme A, flavin adenine dinucleotide, flavin mononucleotide, and nicotinamide adenine dinucleotide phosphate).

Fission (biology)

binary fissionfissionschizogony
Mitochondria and Chloroplasts: generate energy for the cell. Mitochondria are self-replicating organelles that occur in various numbers, shapes, and sizes in the cytoplasm of all eukaryotic cells. Respiration occurs in the cell mitochondria, which generate the cell's energy by oxidative phosphorylation, using oxygen to release energy stored in cellular nutrients (typically pertaining to glucose) to generate ATP. Mitochondria multiply by binary fission, like prokaryotes. Chloroplasts can only be found in plants and algae, and they capture the sun's energy to make carbohydrates through photosynthesis.
The object experiencing fission is usually a cell, but the term may also refer to how organisms, bodies, populations, or species split into discrete parts.

Archaea

archaeonarcheaarchaebacteria
Prokaryotes include bacteria and archaea, two of the three domains of life.
Archaea and bacteria have generally similar cell structure, but cell composition and organization set the archaea apart.

Actin

alpha-actinF-actinthin filament
The subunit protein of microfilaments is a small, monomeric protein called actin.
It can be present as either a free monomer called G-actin (globular) or as part of a linear polymer microfilament called F-actin (filamentous), both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division.