Table of Contents
plural: cell matrices
cell ma·trix, ˈmeɪtɹɪks
An insoluble, dynamic gel in the cytoplasm, believed to be involved in cell shape determination and locomotive mechanism, particularly across a solid substrate; cytoplasmic matrix
A cell is the structural, functional and biological unit of all organisms. It is a membrane-bound structure containing the protoplasm. The protoplasm is the fluid living content of the cell. In certain references, protoplasm is a synonymous of the term cytoplasm. In other sources, the protoplasm includes the nucleoplasm. Thus, in stricter sense, the protoplasm is basically made up of the cytoplasm and the nucleoplasm. The cytoplasm, in turn, is the protoplasmic contents between the cell membrane and the nuclear envelope. The fluid portion of the cytoplasm is called the cytosol. It is the liquid matrix that surrounds the organelles inside the cell. The cytosol is sometimes referred to as the cytoplasmic matrix, cytomatrix, or cell matrix.
The cell matrix is a dynamic gel in the cytoplasm of the cell. The cell matrix is described as a dynamic structure because it may change from fluid (sol) to elastic (gel) then back again to being fluid.
The cell matrix consists of the three major cytoskeletons: polymeric microtubules, actin microfilaments and intermediate filaments interacting with a number of other proteins. The microfilament (also called actin filament) is a helical polymer of G-actin sub-units, with diameter of 7 nm. It provides mechanical support for the cell or maintains structural integrity of the cell by forming a band just beneath the cell membrane. It also participates in certain cell junction by linking transmembrane proteins (e.g., cell surface receptors) to cytoplasmic proteins. It also anchors the centrosomes at opposite poles of the cell during mitosis. It particularly aids in the contraction of the cell during cytokinesis. It is also involved in cytoplasmic streaming (i.e. Intracellular movement, or the flowing of cytoplasm within cells). It enables cell locomotion (through lamellipodia, filopodia, or pseudopodia). It could also interact with myosin (“thick”) filaments in skeletal muscle fibers to provide the force of muscular contraction. The microtubules are cytoplasmic tubules that serve as structural components of cytoskeleton, cilia, and eukaryotic flagella. A microtubule is made up of polymers of alpha- and beta-tubulin dimers. It is a tubular structure with diameter of 25 nm, length ranging from 200 nm to 25 micrometers, and wall thickness of 5 nm. It exhibits polarity and are organized by a microtubule organizing centers (e.g. centrioles and basal bodies). Its functions are associated with providing intracellular shape, locomotion, and transport. For instance, in cellular division, the microtubules are a source of spindle fibers. They give rise to the spindle apparatus that plays an important role in moving and separating chromosomes. There are three main subgroups of microtubules: the polar microtubules (those extending across the cell, as in from centrosome to centrosome), the astral microtubules (those that anchor the spindle poles to the cell membrane), and the kinetochore microtubules (those that extend from the centrosome to the kinetochore protein in the centromere of the chromosome). The intermediate filaments are polymers comprised of two anti-parallel helices or dimers of varying protein sub-units with diameters ranging from 8 to 12 nm. Examples are vimentin (mesenchyme), glial fibrillary acidic protein (glial cells), neurofilament proteins (neuronal processes), keratins (epithelial cells), and nuclear lamins.
The cell matrix is believed to be involved in cell shape determination and locomotive mechanism, particularly across a solid substrate.
- “cell” + “matrix”, from Middle English matrice, from Late Latin mātrīx, mātrīc-, from Latin “breeding-animal”, from māter, mātr-, (“mother”)
- cytoplasmic matrix
© Biology Online. Content provided and moderated by Biology Online Editors