Biology - Membranes Quick

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Where are the phospholipids present in membranes?
They make up the bilayer
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What is the function of phospholipids?
They act as a partially permeable membrane
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Where are glycolipids in membranes, and what are they made of?
They project from external surface of membrane, and are a carbohydrate attached to a lipid
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What are the functions of glycolipids?
Cell signalling (act as receptors), cell recognition (act as antigens), attach to water to stabilise membrane
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Where is cholesterol in a membrane?
It fits between the tails of the phospholipids in the bilayer
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What is the function of cholesterol?
It regulates the fluidity by stabilising the membrane
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Where are proteins found in a membrane?
Intrinsic proteins spans the bilayer, extrinsic proteins are found in one place
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What are the functions of proteins?
Can be enzymes, and can form channels or act as carriers to transport substances across the membrane
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Where are glycoproteins found in a membrane, and what do they consist of?
They pproject from the external side of the membrane, and consist of a carbohydrate attached to a protein
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What are the functionc of glycoproteins?
Cell signalling (act as receptors), cell recognition (act as antigens), cell adhesion, and attach to water to stabilise membrane
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What is a carrier protein?
A protein with a specific shape that complements the shape of a substance to be transported across the membrane - used in active transport and facilitated diffusion
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What is simple diffusion?
The movement of molecules form a region of high concentration, of that molecule, to a region of lower concentration, down a concentration gradient - no ATP is required
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What is facilitated diffusion?
The movement of molecules from a region of high concentration of that molecule to one of lower concentration, using 2 types of intrinsic membrane proteins (carrier and channel proteins) - no ATP is required
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What is osmosis?
The movement of water molecules from a region of high water to potential to one of low water potential, where water moves through the bilayer or through specific protein channels called aquaporins - no ATP is required
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What is active transport?
The movement of molecules or ions across a membrane against the concentration gardient, using intrinsic carrier proteins in the membrane as pumps - ATP is required
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What is cytosis?
The movement of large quantities of materials in or out of a cell, where the membrane can easily form vesicles that can fuse with or break off from the plasma membrane to allow the bulk transport - ATP is required
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What kind of molecules does simple diffusion move?
Gases such as oxygen and carbon dioxide, small molecules and lipid-based molecules
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What kind of molecules does facilitated diffusion move?
Channels are very specific to one type of ion, and can be gated, and carriers have a very specific shape to only allow a certain molecule to bind
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What kind of molecules does osmosis move?
Water molecules
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What kind of molecules does active transport move?
Large or charged molecules
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What kind of molecules does cytosis move?
Large molecules or particles e.g. hormones, bacteria, or materials to build plant cell walls
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What are the 4 factors affecting the rate of diffusion?
Surface area (directly proportional), concentration gradient (directly proportional), temperature (directly proportional0 and diffusion distance (inversely proportional)
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What is the test for lipids?
Add ethanol to the substance, and then double the volume with water - if the substance is a lipid, the resulting mix is a cloudy, white emulsion
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What happens in cell signalling?
Receptors on cells bind to hormones, drugs, and other cells, leading to a series of reactions within the cell
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How does the temperature affect membrane permeability?
As the temperature increases, the phospholipids gain kinetic energy, and move more, meaning they will begin to move apart from each other, increasing the cell's permeability
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How does adding an inorganic solvent affect permeability?
The molecules from the solvent will get in betweeen the phospholipids, breaking them up, meaning the permeability increases
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Other cards in this set

Card 2

Front

What is the function of phospholipids?

Back

They act as a partially permeable membrane

Card 3

Front

Where are glycolipids in membranes, and what are they made of?

Back

Preview of the front of card 3

Card 4

Front

What are the functions of glycolipids?

Back

Preview of the front of card 4

Card 5

Front

Where is cholesterol in a membrane?

Back

Preview of the front of card 5
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