violet and an octopus‚ they are all built in essentially the same way. The most basic similarity is that all living things are composed of one or more cells. This is known as the Cell Theory. • our knowledge of cells is built on work done with microscopes • English scientist Robert Hooke in 1665 first described cells from his observations of cork slices. Hooke first used the word “cell”. • Dutch amateur scientist Antonie van Leeuwenhoek discovered microscopic animals in water • German scientists
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happen to the cell if the cell membrane (plasma membrane)‚ fails to work? Why? Are there any disorders that can be affected by the cells or plasma membrane? Explain? Some cool facts that I have learned about cells are you need a scanning electron or transmission electron microscope to view a cell because cells range in size from 1 to 100 micrometers. Did you know that cells contain genetic material like DNA‚ nucleic acid and cytoplasm? Our body’s cells contain 23 pairs of chromosomes! Again‚ great job
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particles was discussed. CaCO3 nano particles with an average particle size of approximately 15.75 nm were successfully obtained by stirring rotation speed at 900 rpm. The structural analysis was conducted using a Scanning Electron Microscope (SEM) and a Field Emission Scanning Electron Microscope (FESEM) and results showed that the increasing
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thus deriving the name. However what Hooke actually saw was the dead cell walls of plant cells (cork) as it appeared under the microscope. Hooke’s description of these cells was published in Micrographia. The cell walls observed by Hooke gave no indication of the nucleus and other organelles found in most living cells. The first man to witness a live cell under a microscope was Anton van Leeuwenhoek‚ who in 1674 described the algae Spirogyra. Van Leeuwenhoek probably also saw bacteria. Formulation
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What theory states that all living things are composed of cells? Cell theory What type of microscope would be best for studying the detailed structure of the surface of a plasma membrane? Scanning electron microscope The two basic types of cells are ______ and ______. Prokaryotic . . . eukaryotic When using a light microscope to view a cell you obtained from scraping under your fingernails‚ you notice that the cell lacks a nucleus; therefore‚ you conclude that the cell must be a type
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alabaster. Various alabaster samples have been collected from Wadi Sannur quarry and Wadi Assiuty quarry. Archaeological samples were taken from the statues and alabaster monuments in Luxor and Karnak temples. These samples were studied by Polarizing microscope‚ Thin sections were prepared from the studied samples‚ then Petrographical examination and photography was carried out under the polarizing
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Carbon Nanotubes Abstract Carbon nanotubes (CNTs) are a recently discovered allotrope of carbon. They take the form of cylindrical carbon molecules and have novel properties that make them potentially useful in a wide variety of applications in nanotechnology‚ electronics‚ optics‚ and other fields of materials science. They exhibit extraordinary strength and unique electrical properties‚ and are efficient conductors of heat. Inorganic nanotubes have also been synthesized. A nanotube is a member
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Active transport: requires that a cell expend energy to move molecules across a membrane against the solute’s concentration gradient (the side where it is more concentrated) Feedback inhibition: Metabolic reaction is blocked by its products. A product acts as an inhibitor of one of the enzymes in the pathway to regulate metabolism. Centriole: a structure in an animal cell composed of microtubule triplets arranged in a 9+0 pattern. An animal usually has a pair of centrioles within each of its centrosomes
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very small the radii of most atoms fall within the range of 5 x 10^-11 m to 2 x 10^-10m atoms can be seen in scanning electron microscopes atoms can be moved 4.2 Structure of the Nuclear Atom Overview Lots of Dalton’s theory is accepted except that atoms can be divided Atoms can be divided into three subatomic particles Protons Neutrons Electrons Subatomic Particles Electrons Discovered by UK physicist J.J. Thomson (1856-1940) Are negatively charged subatomic particles. Thomson’s Experiment
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particles including proton‚ neutron‚ and electrons. 2 Protons Nucleus 2 2 Nucleus Neutrons Electrons 2e– Electron cloud Simple Chemistry for Life Science • Atomic structure of the 4 common elements. – The number of electrons in the outermost shell determines the chemical properties of an atom Electron First electron shell (can hold 2 electrons) Hydrogen (H) Atomic number 1 Outer electron shell (can hold 8 electrons) Carbon (C) Atomic number 6 Nitrogen
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