Movement across cell membranes

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  • Created by: amm242
  • Created on: 01-05-18 16:32
Define diffusion
The net movement of molecules or ions from an area of high concentration to an area of low concentration, until equilibrium is reached.
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Define facilitated diffusion
Diffusion involving the presence of protein carrier molecules to allow the passive movement of substances across plasma membranes.
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What effects the rate of diffusion?
Concentration gradient, surface area, thickness of exchange surface, temperature
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Why is faciliated diffusion a passive process?
It doesn't require ATP energy, only the built-in kinetic energy of the molecules themselves
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Define osmosis
The net movement of water from an area of high water potential to an area of low water potential through a selectively permeable membrane, until equilibrium is reached
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What's the water potential of pure water?
Zero
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What does a more negative water potential value suggest?
Lower water potential
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What happens when water enters a red blood cell by osmosis?
It swells and bursts (haemolysis)
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What happens when water enters a plant cell by osmosis?
It swells and becomes turgid but doesn't burst due to the cell wall.
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Define active transport
The net movement of molecules or ions from an area of low concentration to an area of high concentration using ATP and carrier proteins
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Why do cells that carry out active transport need mitochondria?
It requires ATP energy which is supplied by the mitochondria
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What happens to ATP when it binds to the carrier protein?
Splits into ADP and a phosphate molecule, changing the shape of the protein, allowing the molecule into the cell.
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Define co-transport
Transport of one substance along with another across a plasma membrane through the same carrier protein
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Is sodium moving out of the epithelial cell passive or active?
Active
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Is sodium moving into the epithelial cell passive or active?
Passive
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Is glucose molecules moving into the epithelial cell passive or active?
Passive
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How do microvilli increase diffusion?
They provide a larger surface area for the insertion of carrier proteins
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Why is the term co-transport used for absorption of glucose and amino acids from the ileum?
They are drawn into the cells along with sodium ions that have been actively transported out by sodium-potassium pump
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Card 2

Front

Define facilitated diffusion

Back

Diffusion involving the presence of protein carrier molecules to allow the passive movement of substances across plasma membranes.

Card 3

Front

What effects the rate of diffusion?

Back

Preview of the front of card 3

Card 4

Front

Why is faciliated diffusion a passive process?

Back

Preview of the front of card 4

Card 5

Front

Define osmosis

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Preview of the front of card 5
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