and the inside of cells‚ for example. If the oncentration of an ion is too high outside a cell‚ water will br pulled out of the cell by osmosis in order to increase the water potential and thus retore balance. This is the case in ORT (oral rehydration therapy) which is used to treat diarrhea ocurring due to cholera for example. The ORT packs ontain salt and electrolytes which are transported into the epithelial cells after ingestion and thus lower the water potential of the cell by causing water to
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Liposomes Definition and background10 Liposomes were discovered in the early 1960’s and subsequently studied as cell membrane models. They have since gained recognition in the field of drug delivery. Liposomes are spherical vesicles which can be thought of as a hollow sphere they are composed of a bilayer membrane which entraps an aqueous core. The particle size of liposomes ranges from 20 nm to 10 μm in diameter. Liposomes vary in charge and in size depending on their manufacturing protocol
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paracrine ‚ autocrine signaling‚ and cell-cell contact (Fig. 15-2). Endocrine signaling is long distance signaling. An example would be pancreatic cells secreting insulin. Paracrine signaling is for close proximity. An example would be a nerve cell releasing neurotransmitters. In autocrine signaling the cell that produces the ligand also contains the receptor for that ligand. This is how cancer cells work. In signaling by plasma membrane attached proteins‚ the target cell does something in response to
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osmosis‚ turgor pressure: Osmosis is the diffusion of water molecules across a cell membrane. When osmosis results in water molecules entering a plant cell‚ the molecules exert a pressure against the cell wall‚ called turgor pressure. 3. hypertonic‚ plasmolysis : hypertonic solution has a higher solute concentration than the cytosol of a cell. In a hypertonic solution a plant cell will lose water and shrink away from the cell wall‚ a process called plasmolysis. MULTIPLE CHOICE 1. d 2. b 3. a 4
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Chapter 4: Membrane Structure and Function Fluid Mosaic Model 1. Consistency of membrane is solid enough to form a boundary‚ but flexible and permeable like a fluid. 2. Proteins scattered throughout - Embedded or on the surface - Can move around laterally 3. Phospholipid from bilayer‚ make up most of membrane 4. Glycolipids have carbohydrate chains attached. 5. Hydrophilic heads point out/into the cell 6. Hydrophobic tails point out towards each other Proteins 1. Glycoproteins: have
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Simple diffusion The term simple diffusion refers to a process whereby a substance passes through a membrane without the aid of an intermediary such as a integral membrane protein. The force that drives the substance from one side of the membrane to the other is the force of diffusion. In order for substances to pass through a cell membrane by simple diffusion it must penetrate the hydrophobic core of the phospholipid bilayer. The types of molecules that can do this are themselves substantially
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together and also tied somehow to the foundation. Similarly‚ cells within tissues and organs must be anchored to one another and attached to components of the extracellular matrix. Cells have developed several types of junctional complexes to serve these functions‚ and in each case‚ anchoring proteins extend through the plasma membrane to link cytoskeletal proteins in one cell to cytoskeletal proteins in neighboring cells as well as to proteins in the extracellular matrix.
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intracellular fluid and extracellular fluid in the first observation is completely obvious. When reading the words intracellular and extracellular it can be seen that one is the interior of the cell and the other is the exterior of the cell. Intracellular fluid is restricted to the interior of the cell‚ and the cell membrane is the borderline of cytosol or cytoplasmic matrix. The compartments of the intracellular fluid are very important to know‚ as it contains mostly water with some ions such as chloride
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extracellular‚ whereas most of the potassium ions (approximately 90%) are intracellular. This unequal distribution of ions results in a voltage difference across cell membranes. Extracellular fluid can be divided into interstitial fluid and blood plasma. Interstitial fluid‚ sometimes referred to as tissue fluid‚ fills the spaces in between cells‚ it is exactly the same as blood plasma‚ except it does not contain proteins. When blood plasma gets pushed out of through the capillary wall it leaves the proteins
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concentrations of alcohol on the membrane structure of a beetroot a) Decide what you think will be the effect of alcohol on beetroot cell surface membranes and how this will affect their permeability. Write down your idea as a hypothesis that you can test‚ and support your idea with biological knowledge. Hypothesis “The greater the concentration of the alcohol the more red pigments (betalains) move into the solution.” Biological knowledge: The exposure of the beetroot cell membrane to alcohol makes it
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