BY1 WJEC cell membranes and transport

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  • Created by: rosie25
  • Created on: 23-03-14 21:06
What is the cell membrane made of?
Proteins and phospholipids
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What is the structure of phospholipids in the membrane?
Can form bilayers. One layer has hydrophilic (likes water) head pointing inwards. The other has its heads pointing outwards. The hydrophobic tails point to the centre in both layers
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What is the function of an extrinsic protein?
Occur on surface, provide structural support and recognition between cells.
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What is the function of an intrinsic protein?
Extend across both layers. Some act as carriers across membrane, others allow active transport.
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What does the fluid part mean in the 'fluid mosaic model'?
Phospholipids can move so the structure is always moving (fluid)
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What does the mosaic part mean in the 'fluid mosaic model'?
Proteins vary in shape and size so each one is different, like a mosaic
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What is the structure and function of cholesterol?
Found in animal cells. Fits between phospholipids, increasing rigidity and stability
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What are glycolipids and where are they found?
Lipids and polysaccharides- found in outer layer of membrane
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What can move through the membrane via phospholipids?
Lipid-soluble substances
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What is the cell surface membrane said to be?
Selectively permeable
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What is osmosis?
Passage of water from a high water potential to a lower WP, through a partially permeable membrane.
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What is the water potential of pure water?
0
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Does addition of solutes increase or decrease the WP?
decrease
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What is a turgid cell?
Where water pushes cytoplasm against cell wall
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What is the equation for water potential?
WP=solute potential + pressure potential
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What is diffusion?
Movement of molecules from a high concentration to low conc.
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What are the 5 main things that affect diffusion?
Concentration gradient, distance, surface area, thickness and temperature
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What is facilitated diffusion?
Allows faster movement of molecules that can't pass through the membrane. It occurs where there are proteins.
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What does active transport require and what are the key features of it?
Requires energy. It moves in opposite direction to diffusion, supplied by ATP, occurs through carrier proteins.
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What will active transport not take place in presence of?
A respiratory enhibitor
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Other cards in this set

Card 2

Front

Can form bilayers. One layer has hydrophilic (likes water) head pointing inwards. The other has its heads pointing outwards. The hydrophobic tails point to the centre in both layers

Back

What is the structure of phospholipids in the membrane?

Card 3

Front

Occur on surface, provide structural support and recognition between cells.

Back

Preview of the back of card 3

Card 4

Front

Extend across both layers. Some act as carriers across membrane, others allow active transport.

Back

Preview of the back of card 4

Card 5

Front

Phospholipids can move so the structure is always moving (fluid)

Back

Preview of the back of card 5
View more cards

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