phosopholipids are charged and so are water soluable so it can be dissolved in water.When poured into water the phosopholipids the heads dissolve and the tails float on top.
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When does a phospholipic bilayer occur
When there is a ambiotic layer when it has a charges head and an uncharged tail which are not bonded together but just move-fluid structure.
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What are the componants of the membrane
The phosopholipids are free to move which is why membranes form so easily which have intrinsic and extrinistic proteins which make the fluid mosiac model as it moves around.
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What is the function of the membrane
Role to get things over the membrane
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How are proteins held in the bilayer
Proteins are made of amino acids which can be made of hydrophobic elements, these regions of no charge which helps to hold the protiens in its place. The Intrinstric proteins are bonded to the hydrophillic heads.
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What are "POLO" proteins
Another name for channel proteins which allow molecules across the membrane as it had a hole through the membrane that molecules can diffuse through.
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What do Carrier proteins do
A molecule will sit in the carrier protien, this causes the proteins to change shape,the change in shape allows it ti move through the membrane. Very specific and only lets certain molecules through.
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What are glycoproteins
Proteins that are important for sticking cells to cells and also acts as recetors but is for a specific molecule and causes effects to the inside of the cell E.g. insulin
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What is a glycolipid
An example is antigens but are basically "label" cells in the body which helps immune system recognises cells.
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Explain what cholesterol is
Made in the liver but without it the membrane stops working. It is a circular molecule and sits between molecules in the bilayer and has a polar and non-polar regions. It regulates the fluidity of the membrane and gets between the phospholipids.
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What happens to the membrane when the tempeture is increased
An increase in tempeture results in an increase of movement because there is more Kinetic Energy which leads to gaps and increased permeability. The proteins will denature so there is a loss of function and this also affects the permeability.
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Name a solvent and an example
Organic solvents: non polar regions or contain regions, they sit between the phospholipids so it becomes more permeable. An example is Alcohol which cant brew above 15c as it destroys the membranes at lower concentrations it will affect its function
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What is diffusion
It is Movement of molecules from a low concentration to a high concentration but only works for liquids and gases. It is a passive process because it doesnt use energy and the molecules will spread out because they are moving constantly.
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What is a solute
substance that is dissolved in a solvent forming a solution
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What is concentration
amount of the solute in a certain volume of aqueous solution
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what is water potential
pressure exerted by water molecules as they collide with a membrane or container
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what is the measure of water potential
It is measured in the units of pressure: pascals (pa) or kilopascals (kpa). Pure water potential has a water potential of 0kpa which is the highest value as the presence of a solute lowers the potential below 0 so they all have negative values.
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What happens when solutions of different concentrations are seperated by a partially permeable membrane
The water molecules can move but the solute cannot so there is a net movement of water from high to low water potential and this will contuine untill an equillibrium is reached.
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Describe the molecules involved of Diffusion
Small molecules can diffuse easily if it has no charge; it is down the gradient. A polar molecule which is not fully charged can get slowly across the memebrane and is also down the gradient. Ionic molecules cannot diffusse except very small molecule
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What factors determine what gets across the membrane
Size and Charge
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Describe the process involving facillitated diffusion and channel proteins
This is for polar molecules and ions; the channel proteins are open channels in the membrane it lets specific molecules through to the other side.
A specific molecules binds to the site in the proteins which changes its shape and allows the molecule through. It is always high to low concentration and it a passive process.
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What factors in the membrane affect diffusion.
Thickness, Surface area, Charge of the molecule, Size of the molecule, Number of transport proteins.
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Other cards in this set
Card 2
Front
What happends to membranes in water
Back
phosopholipids are charged and so are water soluable so it can be dissolved in water.When poured into water the phosopholipids the heads dissolve and the tails float on top.
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