Cell membranes

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What is the purpose of a cell membrane?
To control which substances enter and leave the cell.
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Name one way in which substances can move across a cell membrane?
OSMOSIS, DIFFUSION OR ACTIVE TRANSPORT.
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What are cell membranes made of?
Lipids, proteins and carbohydrates.
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Define a receptor protein.
It is a protein in which allows cells to detect chemicals released from other cells.
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Name a similarity between glycolipids and glycoproteins.
They both have a carbohydrate attached to them
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What is the model used to describe a cell membrane called?
Fluid Mosaic model
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Why does the centre part of a cell membrane not allow water-soluble substances to diffuse through it?
Because the tails of phospholipids are hydrophobic and therefore are located in the centre.
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What type of substances can diffuse through the hydrophobic tails of a phospholipid bilayer?
Small, non-polar substances.
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Why is cholestrol used in cell membranes?
To give the membrane stability.
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How does cholesterol provide stability?
It binds to the tails of phospholipids, therefore causing them to bunch together and move less, this makes the membrane less fluid and more rigid.
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How does cholestrol also help with the barrier against polar substances?
It has hydrophobic parts.
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How can temperature affect membranes?
It affects how much phospholipids can move.
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At which temperature would phospholipids lack energy?
Temperatures below 0 degrees.
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At temperatures below 0 degrees what is there a possibility of forming?
Ice crystals
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As the temperature increases between 0 and 45, what happens to the permeability of a membrane?
It is increased.
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Why is the permeability of a membrane increases when temperature increases from 0 to 45 degrees?
Because phospholipids have more energy and can therefore move more.
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At which temperatures does the phospholipid bilayer begin to break down?
above 45 degrees.
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Why is the membrane put under pressure at temperatures above 45 degrees?
Because the water inside the cell expands.
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Why is permeability increased at temperatures above 45 degrees?
Because channel and carrier proteins denature so therefore cannot control substances leaving and entering the cell.
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Other cards in this set

Card 2

Front

Name one way in which substances can move across a cell membrane?

Back

OSMOSIS, DIFFUSION OR ACTIVE TRANSPORT.

Card 3

Front

What are cell membranes made of?

Back

Preview of the front of card 3

Card 4

Front

Define a receptor protein.

Back

Preview of the front of card 4

Card 5

Front

Name a similarity between glycolipids and glycoproteins.

Back

Preview of the front of card 5
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