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| Cell Membrane or Plasma Membrane |
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Definition
is the outermost boundary of a living cell.
its function is to regulate the passage of materials into and out of the cell.
they exhibit Selective Permeability, allowing some substances to cross more easily than others.
acts as the site of cellular recognition or the ability of an organism to distinguish between "self" and "non-self" which plays an important role in immunity. |
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| is a structure of cell membranes that are composed of a bi layer of phospholipids with embedded and attached proteins. |
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some proteins help maintain cell shape and coordinate changes inside and outside the cell through their attachment to the Cytoskeleton and Extracellular Matrix.
some proteins function as receptors for Hormones from other cells.
some membrane proteins function as Enzymes. |
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| the key ingredient of biological membranes, spontaneously self-assemble into simple membranes. |
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| a two layer sheet formed by Phospholipids in which Hydrophilic are exposed to water and Hydrophobic are shielded from water. |
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are either Peripheral Proteins or integral Proteins.
some form channels or tunnels that shield ions another hydrophilic molecules as they pass through the hydrophobic center of the membrane.
others serve as pumps, using energy to actively transport molecules, into or out of the cell. |
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| attached to the membrane surface. |
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| embedded within the phospholipid bilayer. |
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| is the movement of molecules from an area of high concentration to an area of low concentration without energy being expended. The molecules move down their CONCENTRATION GRADIENT (from high to low). two types are SIMPLE DIFFUSION and OSMOSIS. |
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is the tendency of molecules to spread out evenly in an available space.
three physical factors that affect the rate of Diffusion are temperature, molecular size, and state of matter. |
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when molecules move from an are of high concentration to an area of low concentration until they reach a point at which they are spread equally in all areas is call the point of EQUILIBRIUM.
where the concentration of molecules are the same throughout. |
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| warm temperatures cause molecules to diffuse faster than colder temperatures. |
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| large molecules diffuse more slowly than small molecules. |
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| matter exists in three basic states, Solids, Liquids, and Gasses. Solids diffuse more slowly than gasses. Liquids diffuse at a rate somewhere in between. |
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is the diffusion of water molecules from an area of high concentration to an area of low concentration across a membrane until Equilibrium is reached.
also a type of Passive Transport. |
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describes the ability of a solution to cause a cell to gain or lose water.
mostly depends on the concentration of a solute on both side of the membrane. |
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| the relative concentration of SOLUTES vs. SOLVENTS into two different environments, such as inside vs. outside of a cell. |
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| are the substances which are dissolved into other substances called SOLVENTS. |
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| the substance that SOLUTES are dissolved in. |
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a combination of SOLUTES and SOLVENTS.
ex: dissolving salt (solute) into water (solvent) to make a solution of saltwater. |
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| water will always move in the direction of the greater concentration of Solutes. |
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| if a cell is placed into a HYPERTONIC solution, there is a higher concentration of solutes outside of the cell (than inside of the cell), and water molecules will move out of the cell causing it to shrink. In plant cells this is called PLASMOLYSIS and in animal cells it is called CRENATION. |
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| is a cell is place into a HYPOTONIC solution, there is a lower concentration of solutes outside of the cell and water molecules will move into the cell. In plant cells, the cell will expand and fill with water causing TURGOR PRESSURE but will not burst due to the presence of a strong Cell Wall. In animal cell, the cell may burst and this is called CYTOLYSIS. |
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| if a cell is places in an ISOTONIC solution, the concentration of solutes is the same on both sides of the membrane and the net movement of water will be zero. |
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the control of water balance.
in order for cells to survive in a hypotonic or hypertonic environment, they must engage in OSMO-REGULATION. |
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cells move molecules from an area of low concentration to an area of high concentration using energy. These molecules move against the concentration gradient (low to high).
several different types. |
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| is the movement of large molecules across membranes and Is a type of ACTIVE TRANSPORT. |
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| is used to import substances such as food and water. |
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| Phagocytosis (cell eating) |
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| is the import of food molecules into the cell. |
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| Pinocytosis (cell drinking) |
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| is the import of liquids into the cell. |
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| is used to export bulky molecules, such as proteins or polysaccharides. |
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