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See also List of basic cell biology topics.

Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly An academic discipline or field of study is a branch of Knowledge which is taught or Researched at the college or university level The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called Physiology (from Greek grc φύσις physis, "nature origin" and grc -λογία -logia) is the study of the mechanical physical In Cell biology, an organelle (pronunciation /ɔː(rgəˡnɛl/ is a specialized subunit within a cell that has a specific function and is usually separately enclosed The cell cycle, or cell-division cycle, is the series of events that take place in a eukaryotic cell leading to its replication Cell division is a process by which a cell, called the parent cell divides into two or more cells called daughter cells. This is done both on a microscopic and molecular level. A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by Cell biology research extends to both the great diversity of single-celled organisms like bacteria and the many specialized cells in multicellular organisms like humans. The cell is the structural and functional unit of all known living Organisms It is the smallest unit of an organism that is classified as living and is often called The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus

Knowing the composition of cells and how cells work is fundamental to all of the biological sciences. Foundations of modern biology There are five unifying principles Appreciating the similarities and also differences between cell types is particularly important to the fields of cell and molecular biology. Molecular biology is the study of Biology at a molecular level These fundamental similarities and differences provide a unifying theme, allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. A personal and cultural value is a Relative ethic value, an assumption upon which implementation can be extrapolated Research in cell biology is closely related to genetics, biochemistry, molecular biology and developmental biology. Genetics (from Ancient Greek grc-Latn genetikos, “genitive” and that from grc-Latn genesis, “origin” a discipline of Biology, is Biochemistry is the study of the chemical processes in living Organisms It deals with the Structure and function of cellular components such as Molecular biology is the study of Biology at a molecular level Developmental Biology is the official journal of the Society for Developmental Biology.

Understanding cells in terms of their molecular components.
Understanding cells in terms of their molecular components.

Contents

Processes

Movement of proteins

Proteins (red and green stain) at different locations in a cell.
Proteins (red and green stain) at different locations in a cell.

Each type of protein is usually sent to a particular part of the cell. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl An important part of cell biology is the investigation of molecular mechanisms by which proteins are moved to different places inside cells or secreted from cells.

Most proteins are synthesized by ribosomes in the cytoplasm. Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Ribosomes ( from ribo nucleic acid and "Greek soma ( meaning body") are complexes of RNA and Protein that The cytoplasm is the contents of a cell that is enclosed within the Plasma membrane. This process is also known as protein biosynthesis or simply protein translation. Protein biosynthesis (synthesis is the process in which cells build Proteins The term is sometimes used to refer only to protein translation but more Translation is the first stage of Protein biosynthesis (part of the overall process of Gene expression) Some proteins, such as those to be incorporated in membranes (known as membrane proteins), are transported into the endoplasmic reticulum (ER) during synthesis. Also see Transmembrane protein. A membrane protein is a Protein molecule that is attached to or associated with the membrane The endoplasmic reticulum (Greek endo = "within" (prefix plásma = "formed entity" Latin reticulum = "little net" or ER, is an Organelle This process can be followed by transportation and processing in the Golgi apparatus. The Golgi apparatus (also called the From the Golgi, membrane proteins can move to the plasma membrane, to other subcellular compartments, or they can be secreted from the cell. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer The ER and Golgi can be thought of as the "membrane protein synthesis compartment" and the "membrane protein processing compartment", respectively. There is a semi-constant flux of proteins through these compartments. ER and Golgi-resident proteins associate with other proteins but remain in their respective compartments. Other proteins "flow" through the ER and Golgi to the plasma membrane. Motor proteins transport membrane protein-containing vesicles along cytoskeletal tracks to distant parts of cells such as axon terminals. Kinesins are a class of Motor proteins found in Eukaryotic cells cytoskeleton (also CSK is a cellular " Scaffolding " or " Skeleton " contained within the Cytoplasm. An axon or nerve fiber is a long slender projectionof a nerve cell or Neuron, that conducts electrical impulses away from the neuron's Cell

Some proteins that are made in the cytoplasm contain structural features that target them for transport into mitochondria or the nucleus. A nuclear localizing sequence ( NLS) is an Amino acid sequence which acts like a 'tag' on the exposed surface of a Protein. In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. In Cell biology, the nucleus (pl nuclei; from Latin la ''nucleus'' or la ''nuculeus'' "little nut" or kernel is a membrane-enclosed Some mitochondrial proteins are made inside mitochondria and are coded for by mitochondrial DNA. In plants, chloroplasts also make some cell proteins. Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis.

Extracellular and cell surface proteins destined to be degraded can move back into intracellular compartments upon being incorporated into endocytosed vesicles. Clathrin is a Protein that is the major constituent of the 'coat' of the clathrin- Coated pits and coated Vesicles formed during Endocytosis Some of these vesicles fuse with lysosomes where the proteins are broken down to their individual amino acids. Lysosomes are Organelles that contain Digestive enzymes (acid Hydrolases. In Chemistry, an amino acid is a Molecule containing both Amine and Carboxyl Functional groups In Biochemistry, this The degradation of some membrane proteins begins while still at the cell surface when they are cleaved by secretases. Secretases are Enzymes that "snip" pieces off a longer Protein that is embedded in the Cell membrane. Proteins that function in the cytoplasm are often degraded by proteasomes. Proteasomes are large Protein complexes inside all Eukaryotes and Archaea, as well as in some Bacteria.

Other cellular processes

Internal cellular structures

Electronmicrograph.
Electronmicrograph. Chemotaxis, a kind of Taxis, is the phenomenon in which bodily cells bacteria, and other single-cell or Multicellular organisms direct their movements A muscles contraction (also known as a muscle twitch or simply twitch) occurs when a Muscle fibre generates tension through the action of Actin A cilium (plural cilia) is an Organelle found in eukaryotic cells Cilia are tail-like projections extending approximately A flagellum ( plural flagella) is a tail-like structure that projects from the Cell body of certain Prokaryotic and Eukaryotic cells and it DNA repair refers to a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its Genome. Programmed cell-death ( PCD) is death of a cell in any form mediated by an intracellular program Metabolism is the set of Chemical reactions that occur in living Organisms in order to maintain Life. See also Gluconeogenesis, which carries out a process wherein glucose is synthesized rather than catabolized Cellular respiration is the set of the metabolic reactions and processes that take place in Organisms cells to convert biochemical energy from Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy.

Techniques used to study cells

Cells may be observed under the microscope. In Cell biology, an organelle (pronunciation /ɔː(rgəˡnɛl/ is a specialized subunit within a cell that has a specific function and is usually separately enclosed Chloroplasts are Organelles found in Plant cells and eukaryotic Algae that conduct Photosynthesis. In Cell biology, an organelle (pronunciation /ɔː(rgəˡnɛl/ is a specialized subunit within a cell that has a specific function and is usually separately enclosed Photosynthesis is a Metabolic pathway that converts Light Energy into Chemical energy. A cilium (plural cilia) is an Organelle found in eukaryotic cells Cilia are tail-like projections extending approximately Microtubules are one of the components of the Cytoskeleton. They have a diameter of 25 nm and length varying from 200 nanometers to 25 micrometers Animals Plants fungi, and Protists are eukaryotes (juːˈkærɪɒt or -oʊt Organisms whose cells are organized into complex The cytoplasm is the contents of a cell that is enclosed within the Plasma membrane. cytoskeleton (also CSK is a cellular " Scaffolding " or " Skeleton " contained within the Cytoplasm. Ribosomes ( from ribo nucleic acid and "Greek soma ( meaning body") are complexes of RNA and Protein that Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units The endoplasmic reticulum (Greek endo = "within" (prefix plásma = "formed entity" Latin reticulum = "little net" or ER, is an Organelle Protein synthesis is the creation of proteins using DNA and' RNA'. A flagellum ( plural flagella) is a tail-like structure that projects from the Cell body of certain Prokaryotic and Eukaryotic cells and it The Bacteria ( singular: bacterium) are a large group of unicellular Microorganisms Typically a few Micrometres in length bacteria have The Golgi apparatus (also called the Glycosylation is the enzymatic process that links Saccharides to produce glycans, either free or attached to Proteins and Lipids This enzymatic The endomembrane system is composed of the different membranes that are suspended in the Cytoplasm within a Eukaryotic cell. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl A lipid bilayer or bilayer lipid membrane ( BLM) is a membrane composed of Lipid molecules (usually Phospholipids. The cell membrane (also called the plasma membrane, plasmalemma, or "phospholipid bilayer" is a Selectively permeable Lipid bilayer A vesicle is a small bubble of liquid within a cell A more formal definition in Cell biology, would be that a vesicle is a relatively small intracellular membrane-enclosed In Cell biology, a mitochondrion (plural mitochondria) is a membrane-enclosed Organelle found in most eukaryotic cells. In Cell biology, the nucleus (pl nuclei; from Latin la ''nucleus'' or la ''nuculeus'' "little nut" or kernel is a membrane-enclosed Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known This includes the Optical Microscope, Transmission Electron Microscope, Scanning Electron Microscope, Fluorescence Microscope, and by Confocal Microscopy. The optical microscope, often referred to as the "light microscope" is a type of Microscope which uses Visible light and a system of lenses to The scanning electron microscope ( SEM) is a type of Electron microscope that images the sample surface by scanning it with a high-energy beam of Electrons A fluorescence microscope (colloquially synonymous with epifluorescent microscope) is a light Microscope used to study properties of organic or inorganic substances Confocal microscopy is an optical imaging technique used to increase Micrograph contrast and/or to Reconstruct three-dimensional Images by

Immunostaining can also be imploded to observe cells. Immunostaining is a general term in Biochemistry that applies to any use of an Antibody -based method to detect a specific Protein in a sample Such examples are:

Purification of cells and their parts

Purification may be performed using the following methods:

See also

Notable cell biologists

George Emil Palade
George Emil Palade

References

  1. ^ Cristianini, N. and Hahn, M. Introduction to Computational Genomics, Cambridge University Press, 2006. (ISBN-13: 9780521671910 | ISBN-10: 0521671914)

External links

Online cell biology textbooks

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