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Home >> Dictionary of Bioinformatics, Biochemistry, Biotechnology >> Cell Ablation - Cell Generation Time
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Cell ablation
The technique of selective destruction of cells used in understanding the role of differentiating cells in the development of an organism. This involves introducing genes encoding cytotoxins such as diphtheria toxin adjacent to cell-specific promoters.
Cell adhesion
The mechanical coupling of one cell to another or of a cell to a solid support. Cell adhesion is mediated by cell-or cell-matrix junctions.
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Cell culture The in vitro growth of cells that are derived from multicellular organisms. These ells are generally of one type.
Cell cycle The stages that a cell passes through between one division ad the next. The cell cycle consists of mitosis and interphase. The interphase in divided into G1, S, and G2. The G1 phase is characterised by a high rate of biosynthesis and growth. In the S phase, doubling of the DNA content due to chromosome replication occurs. In the G2 phase, the final preparations for cell division (cytokinesis) are made.
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Cell differentiation The continuous loss of physiological and cytological characters of young cells that eventually results in the characters of adult cells. The unspecialized cells are modified and specialised for the performance of specific functions. Differentiation results from he controlled induction and repression of genes.
Cell disruption techniques The techniques used to release intracellular proteins and nucleic acids. Different methods are used for disrupting cells. (1) chemical-alkaline conditions are used to release certain proteins. (2) Detergents-ionic detergents such as sodium dodecyl sulphate and nonionic detergents such as Triton X-100 destroy the cell membrane and facilitate cell lysis. (3) Enzymatic, the enzyme lysozyme isolated from egg white breaks down the peptidoglycan wall of bacteria.
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(4) Grinding with an abrasive material such as glass beads, using a mortar and pestle for small scale preparations, or a cell disrupter apparatus for large-scale operations causes physical disruption of the cell wall. (5) Osmotic shock proteins are released from the periplasmic space of Gram-negative bacteria by suspending cells in 20% sucrose followed by resuspending in water.
(6) shearing-this involves passage of cells through a narrow orifice at high pressure. Small-scale operations use a solid shear, while large-scale operations use a liquid shear. (7) Sonication-this involves disruption of the cell wall by high-frequency sound waves.
Cell division Formation of two or more daughter cells from a single parental cell. The nucleus divides first, followed by the formation of a cell membrane between the daughter nuclei.
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Cell-division cycle gene (cdc gene) A gene that controls a specific step(s) in the eukaryotic cell cycle.
Cell fractionation The process of preparing a cell-free extract and separating the cell contents into fractions by centrifugation.
Cell-free extract The soluble protion of the cellular contents after removal of the organelles and cell debris. The product obtained after treating a cell suspension with a substance that destroys the cell wall and/or cell membrane with release of the cytoplasm and cell organelles
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Cell coat
See glycocalyx.
Cell commitment
The commitment of a cell to a certain line of development. This occurs at a particular stage in the life of a cell.
Cell cortex Specialised cytoplasmic layer on the inner surface of the plasma membrane. In animals, it is rich in actin and is responsible for movement of the ell surface.
Cell adhesion molecules (CAMs)
Proteins present in the plasma membrane of cells that mediate cell-cell adhesion by binding to similar proteins on other cells. There are four major classes of CAMs: cadherins, selectins, immunoglobulin (lg) superfamily members and integrins.
Cell-free protein synthesis See in vitro translation.
Cell-free system Fractionated cell homogenate that retains a specific biological function of the intact cell and in which biochemical processes and reactions can be analysed.
Cell-free transcription See in vitro transcription.
Cell-free translation See in vitro translation.
Cell fusion The fusion of cells from different species in vitro or in vivo, to form a single hybrid cell. The cells fuse and coalesce, but their nuclei may remain separated. In the next cell division, a single spindle is formed so that each daughter cell has a single nucleus that contains sets of chromosomes from each parental line. Subsequent divisions usually result in the loss of chromosomes and therefore of genes. The in vitro cell fusion technique known as somatic cell hybridization is used to determine the control of specific genes and their assignment to chromosomes.
Cell generation time
The interval between the beginning of consecutive divisions of a cell. The time taken for a population of single-celled organisms to double its cell number. Successive generations of cells or organism within a population are separated by a time interval known as generation time. The cell regeneration time can be measured with the help of time-lapse microcinematography.
Cell growth
The growth of isolated cells in culture. The phases of cell growth include the lap phase where there is no growth or death, log phase in which there is which there is more cell growth than death, stationary in which cell growth and death are in equilibrium, and a death where death exceeds growth.
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