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42 Cards in this Set
- Front
- Back
Describe the 3 functions of the membrane at the surface of the cell
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Separating cell contents from the outside environment
Controls which substances enter and leave the cell Cell recognition and signalling |
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Describe the 3 functions of the membrane within the cell
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Divide cell into compartments making different functions more efficient
Can form vesicles Control which substances enter and leave the organelle |
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Describe the fluid mosaic model
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Phospholipid molecules from a continuous fluid bilayer
Various protein molecules are scattered through the bilayer some can move around Glycoproteins Glycolipids Cholesterol |
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Describe the role of cholesterol in the cell membrane
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Cholesterol molecules fit between phospholipid tails to make the membrane more rigid/more complete so water molecules and ions cannot pass easily through the membrane
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Describe the role of phospholipids in the cell membrane
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They are the component of the bilateral and molecules automatically arrange themselves so the hydrophilic heads face away and the hydrophobic tails face inwards
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Describe the role of glycolipids and glycoproteins in the cell membrane
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Cell signalling and recognition
Glycoproteins can bind cells together in tissues Some receptor sites allow hormones to bind with the cell which causes the cell to respond in some way |
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Outline the effects of changing temperature in membrane structure and permeability
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Increase in temperature gives molecules more kinetic energy so they move faster. This increased movements of phospholipids makes membranes more permeable
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Describe the role of channel proteins in the cell membrane
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Allows the movement of molecules that are usually too large and too hydrophilic to cross the membrane
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Describe the role of carrier proteins in the cell membrane
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Actively moves some substances across membrane using ATP
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Explain the term cell signalling
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One cell releases a messenger molecule, which travels to another cell where it binds to a receptor on the target cell membrane because the two have complimentary shapes, causing the target cell to respond in some way
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Explain the role of membrane bound receptors where hormones bind
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Hormones bind to a receptor because their shapes are complimentary e.g glucagon released when not enough glucose is in the blood. It binds receptors on the liver cells, causing them to break down stores of glycogen to glucose
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Explain the role of membrane bound receptors where drugs bind
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Drugs bind to a receptor because their shapes are complimentary. They either trigger a response or block the receptor and prevent it working
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A) what is passive transport
B) list three types |
A) no energy needed
B) diffusion, osmosis, facilitated diffusion |
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What 6 things does diffusion depends on
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Temperature: hotter = more k.e
Surface area: larger = faster rate Concentration gradient: higher = faster rate of diffusion Mixing: increases k.e Thickness of exchange surface: thinner surface = faster rate Molecule size: smaller = faster |
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Describe the role of phospholipids in the cell membrane
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They are the component of the bilayer and molecules automatically arrange themselves so the hydrophilic heads face away and the hydrophobic tails face inwards
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Define diffusion
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The movement of molecules from a high concentration to a lower concentration down a concentration gradient
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Define facilitated diffusion in carrier proteins
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Shaped so specific molecule fits in at membrane surface, once molecules is in, protein changes shape to allow molecule through to other side
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Describe active transport
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Refers to the molecule movement across membranes, which use ATP to drive protein pumps within the membrane
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Define endocytosis
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The bulk movement of materials into a cell
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Define exocytosis
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The bulk movement of materials out of a cell
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Define phago
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Solid material
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Define pino
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Liquid material
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List the differences between active transport and facilitated diffusion
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AT is active as uses ATP, FD is passive so kinetic energy, AT only carries molecules one way and opposite to concentration gradient, FD is slower, molecules can accumulate in AT
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Define osmosis
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The movement of water molecules from a high water concentration to a low water concentration across a partially permeable membrane
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Define water potential
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A measure of the tendency of water molecules to diffuse from one place to another
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Describe the role of glycolipids and glycoproteins in the cell membrane
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Cell signalling and recognition
Glycoproteins can bind cells together in tissues Some receptor sites allow hormones to bind with the cell which causes the cell to respond in some way |
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If an animal cell is placed in pure water what will happen
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The water enters cell by osmosis causing it to swell and eventually the membrane will bust (haemolysed)
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If a plant cell is placed in pure water what will happen
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The cell will gradually swell due to osmosis and the membrane will push on the cell wall but won't burst so it will become fully turgid
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If an animal cell is placed in a concentrated salt or sugar solution what will happen
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Water molecules move in to out by osmosis. Cell will shrink and membrane will wrinkle up (cremated)
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If a plant cell is placed in a concentrated salt or sugar solution what will happen
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Water molecules move in to out by osmosis. Cytoplasm and vacuole will shrink, cell surface membrane will pull away from cell well (plasmolysed)
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Define solute
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A solid that dissolves in a liquid
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Define solvent
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A liquid that dissolves solids
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Define solution
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A liquid containing dissolved solids
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Describe what the cell cycle consists of
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Mitosis only occupies a small percentage of the cell cycle the remaining being copying and checking genetic information on DNA and processes associated with growth
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If an animal cell is placed in pure water what will happen
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The water enters cell by osmosis causing it to swell and eventually the membrane will burst (haemolysed)
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Outline the effects of changing temperature in membrane structure and permeability
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Increase in temperature gives molecules more kinetic energy so they move faster. This increased movements of phospholipids makes membranes more permeable
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If an animal cell is placed in a concentrated salt or sugar solution what will happen
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Water molecules move in to out by osmosis. Cell will shrink and membrane will wrinkle up (crenated)
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If a plant cell is placed in a concentrated salt or sugar solution what will happen
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Water molecules move out by osmosis. Cytoplasm and vacuole will shrink, cell surface membrane will pull away from cell well (plasmolysed)
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Explain the term cell signalling
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One cell releases a messenger molecule, which travels to another cell where it binds to a receptor on the target cell membrane because the two have complimentary shapes, causing the target cell to respond in some way
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Explain the role of membrane bound receptors where hormones bind
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Hormones bind to a receptor because their shapes are complimentary e.g glucagon released when not enough glucose is in the blood. It binds receptors on the liver cells, causing them to break down stores of glycogen to glucose
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Explain the role of membrane bound receptors where drugs bind
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Drugs bind to a receptor because their shapes are complimentary. They either trigger a response or block the receptor and prevent it working
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What 6 things does diffusion depends on
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Temperature: hotter = more k.e
Surface area: larger = faster rate Concentration gradient: higher = faster rate of diffusion Mixing: increases k.e Thickness of exchange surface: thinner surface = faster rate Molecule size: smaller = faster |