cell membrane questions

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  • Created by: sarah
  • Created on: 22-04-14 21:52
what is the role of a membrane?
to define boundaries (separate cells or organelles from outside), regulate the flow of information/material, cell signalling
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what does a phospholipid consist of?
a hydrophobic phosphate head, glycerol, 2 fatty acid chains
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what is the name of the model for cell membranes?
Fluid mosaic model
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what can be found in the fluid mosaic model?
phospholipid bilayer, cholesterol, Chanel and carrier proteins , glycoproteins, glycolipids, enzymes, co-enzymes, proteins
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what effect do unsaturated phospholipids have on a membrane
because their chain has a double bond, its tail is kinked. this meanse they can be less tightly packed, and so the membrane is more fluid and permeable.
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what molecules can pass through membranes by passive diffusion?
hydrophobic molecules (e.g carbon dioxide), small uncharged molecules (e.g water)
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what is facilitated diffusion?
the movent of molecules through a membrane, using channel or carrier proteins, with the concentration gradient
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what is active transport?
the movement of molecules through membrane with carierer protiens, using ATP to move against concentration gradient
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why are some membranes (for example mitochondrial inner membranes) folded?
the membranes have enzymes and coenzymes on them, the more membrane there is (folding increases surface area), the more enzymes it can have, so more efficient reactions
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what is endocytosis?
is used as a bulk transport, where the membrane pinches inwards to form vessicles containg the desired molecules
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how does temperature effect membranes?
a higher temperature gives phospholipids more kinetic energy, and so membranes become more "leaky". this enables more molecules to diffuse through
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what is the purpose of cholesterol in a membrane
it gives it more stability. organisms adapted for higher temperatures may need more of this to prevent membranes becoming too leeky
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how do receptors on membranes help to regulate the amount of sugar in blood?
if there is too much sugar in the blood, beta cells in the pancreas release insulin. this is received by a complimentry receptor on a cell membrane, wich will then triger the production of more glucose chanels. so less glucose in blood (more in cell)
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what do beta blockers do?
they block the receptors of heart cells, to stop increase heart rate.
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what are the components of a solution?
solute (the substance that can be dissolved), solvent (the liquid that does the disolving)
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define osmsis
the net movement of water through a partially permeable membrane form a high water potential to a low water potential
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why might muscule cells have large number of channels?
for rapid glucose intake so they can respire quickly and produce more ATP for muscle contraction
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what are aquaporins?
channel proteins for water which increase cell permeability for water by 100x
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what factors effect diffusion gradient
temperature,concentration gradient, stirring, surface area, diffusion distance, size of molecule
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what is water potential measured in?
kiloPascals (kPa)
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Card 2

Front

what does a phospholipid consist of?

Back

a hydrophobic phosphate head, glycerol, 2 fatty acid chains

Card 3

Front

what is the name of the model for cell membranes?

Back

Preview of the front of card 3

Card 4

Front

what can be found in the fluid mosaic model?

Back

Preview of the front of card 4

Card 5

Front

what effect do unsaturated phospholipids have on a membrane

Back

Preview of the front of card 5
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