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Diagram of the plant cell, with the cell wall in green. Cell walls serve similar purposes in those organisms that possess them. They may give cells rigidity and strength, offering protection against mechanical stress. The chemical composition and mechanical properties of the cell wall are linked with plant cell growth and morphogenesis. [11]
The Huygens–Fresnel principle (named after Dutch physicist Christiaan Huygens and French physicist Augustin-Jean Fresnel) states that every point on a wavefront is itself the source of spherical wavelets, and the secondary wavelets emanating from different points mutually interfere. [1] The sum of these spherical wavelets forms a new wavefront.
The plane wavefront is a good model for a surface-section of a very large spherical wavefront; for instance, sunlight strikes the earth with a spherical wavefront that has a radius of about 150 million kilometers (1 AU). For many purposes, such a wavefront can be considered planar over distances of the diameter of Earth.
Cell mechanics is a sub-field of biophysics that focuses on the mechanical properties and behavior of living cells and how it relates to cell function. [1] It encompasses aspects of cell biophysics , biomechanics , soft matter physics and rheology , mechanobiology and cell biology .
Since the cell wall is required for bacterial survival, but is absent in some eukaryotes, several antibiotics (notably the penicillins and cephalosporins) stop bacterial infections by interfering with cell wall synthesis, while having no effects on human cells which have no cell wall, only a cell membrane
Structure of a plant cell. Plant cells are the cells present in green plants, photosynthetic eukaryotes of the kingdom Plantae.Their distinctive features include primary cell walls containing cellulose, hemicelluloses and pectin, the presence of plastids with the capability to perform photosynthesis and store starch, a large vacuole that regulates turgor pressure, the absence of flagella or ...
English: A reworked version of File:Biological_cell.svg. Diagram of a typical animal cell. Organelles are labelled as follows: Nucleolus; Nucleus; Ribosomes (dots on rough reticulum walls) Vesicle; Rough endoplasmic reticulum; Golgi apparatus (or "Golgi body") Cytoskeleton; Smooth endoplasmic reticulum; Mitochondrion; Vacuole; Cytosol; Lysosome ...
Pectins may also be absent from the secondary wall, and unlike primary walls, no structural proteins or enzymes have been identified. [4] Because of the low permeability through the secondary cell wall, cellular transport is carried out through openings in the wall called pits. Wood consists mostly of secondary cell wall, and holds the plant up ...