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18 Cards in this Set
- Front
- Back
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The basic structure of all cell membrane? |
Phospholipid bilayer Hydrophilic Hydrophobic |
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What is the purpose of a cell membrane? |
Different conditions inside and outside By controlling the movement of substances Lipid soluable freely diffuse Prevent water soluable substances entering and leaving the cell Memebrane flexibile and self-sealing |
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What is the arrangement of proteins? |
Interspersed Protein channels Carrier proteins Surface Receptors Structural support |
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How does cholesterol appear within the cell membrane? |
Add strength to the membrane Highly hydrophobic (prevent water/ion loss) Pull fatty acid tails together Reduction in lateral movement Less fluid at higher temperatures |
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What is the purpose of glycolipids? |
Carbohydrate convalently bonded with a lipid Cell surface receptor (recognition) |
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What is the purpose of glycoproteins? |
Recognition sites |
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Why is the bilayer fluid? |
Individual phospholipid can move relative to one another Flexible structure |
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Why is the bilayer described as being a mosaic? |
Proteins Vary in shape, size and arrangement |
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Why can molecules not diffuse simply across the bilayer (limitations)? |
Have to be lipid soluble, too large, charged, polar |
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What is the process of simple diffusion? |
All particles are constantly in motion The motion is random Particles bounce off each other TF The net movement of molecules or ions from an region of high concentration to a region of low concentration Passive process Down a concentration gradient |
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When is diffusion facilitated? |
Passive process (only relying on kinetic energy of the molecules no external input of ATP) |
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How do protein channel facilitate diffusion? |
Water-filled hydrophilic channels Water-soluble ions diffuse through Water molecules |
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How do carrier proteins facilitate diffusion? |
Span whole membrane molecule binds with the protein Molecule is released to the inside of the membrane No ATP is required for this |
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What is the passage of osmosis? |
Net movement, region ,water potential Water potential is the pressure exerted by water molecules The addition of a solute lowers the water potential |
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What is the process of active transport? |
ATP is used to directly move molecules, indirectly move molecules e.g co-transport Substances move against the concentration gradient Selective |
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How are carrier proteins used in active transport? |
Bind molecule Receptor sites carrier protein ATP binds to the protein causing it to split into ADP and p Energy is used to change shape of the proteins carrier Molecule or ion is then released to the opposite side of the cell Phosphate molecule is released from the protein and it reverts back to its original shape |
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How are cells adapted for rapid transport? |
Increase surface area Increase in number of carrier proteins Increase in number of channel proteins |
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How is glucose co-transported out of the ileum |
Sodium ions are actively transported out of the epithelial cell into the blood by the sodium potassium ATPase. This protein pump is present in the membrane of all eukaryotic cells.Sodium ions are now at a lower concentration in the epithelial cell than in the lumen of the small intestine.Sodium ions now diffuse down their concentration gradient through a co-transport protein present in the plasma membrane of the epithelial cell. The energy released as the sodium ions move down their concentration gradient allows glucose molecules to pass through the co-transporter too despite the epithelial cell having a higher concentration of glucose than the lumen of the small intestine.The glucose now passes into the blood via facilitated diffusio |
