Diffusion Flashcards

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1
Q

give the definition of diffusion

A

Diffusion is the net movement of particles (molecules or ions) from an area of higher concentration to an area of lower concentration.

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2
Q

will molecules diffuse both ways ?

A

Molecules will diffuse both ways, but the net movement will be to the area of lower concentration.

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3
Q

explain the concentration gradient

A

The concentration gradient is the path from an area of higher concentration to an area of lower concentration. Particles diffuse down a concentration gradient.

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4
Q

how long does diffusion continue ?

A

This continues until particles are evenly distributed throughout the liquid or gas.

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5
Q

What type of process is diffusion ?

A

passive as no energy is needed for it to happen

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6
Q

what type of molecules is simple diffusion for ?

A

small ,uncharged particles

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7
Q

what is simple diffusion ?

A

Movement of particles from high to low concentration without a protein .WHen particles move directly across a membrane

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8
Q

give an example of simple diffusion ?

A

Example:Oxygen and carbon dioxide can diffuse easily through cell membranes because they’re small, so they can pass through spaces between the phospholipids. They’re also non-polar, which makes them soluble in lipids, so they can dissolve in the hydrophobic bilayer.

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9
Q

what happens with larger molecules when dfffusing across cell membranes ?

A

they go extremely slowly

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10
Q

what happens with charged particle when diffusing ?

A

Charged particles, e.g. ions and polar molecules, would also diffuse slowly because they’re water soluble, and the centre of the bilayer is hydrophobic .particles diffuse through carrier proteins or channel proteins in the cell membrane instead .This is facilitated diffusion

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11
Q

what are carrier and channel proteins called ?

A

transport proteins

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12
Q

what do carrier proteins do ?

A

Carrier proteins move large molecules across the membrane, down their concentration gradient.

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13
Q

do all carrier proteins do all molecules ?

A

Different carrier proteins facilitate the diffusion of different molecules.

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14
Q

how do carrier proteins work ?

A

First, a large molecule attaches to a carrier protein in the membrane. ƒ Then, the protein changes shape. ƒ This releases the molecule on the opposite side of the membrane .

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15
Q

what do channel proteins do ?

A

transport charged particles across the membrane

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16
Q

what are the factors affecting the rate of diffusion?

A

the concentration gradient
the amount of carrier and channel proteins

17
Q

how does the concentration gradient affect the rate of diffusion?

A

the higher the concentration gradient, the faster the rate of facilitated diffusion .As equilibrium is reached, the rate of facilitated diffusion will level off.

18
Q

how does the amount of carrier and channel proteins affect diffusion ?

A

once all the proteins in a membrane are in use, facilitated diffusion can’t happen any faster, even if you increase the concentration gradient.

19
Q

how do you calculate the rate of diffusion ?

A

For a straight line graph, this means finding the gradient of the line.
For a curved graph, it means drawing a tangent and finding the gradient of the tangent.
change in y/change in X

20
Q

what are aquaporins ?

A

special channel proteins that allow the facilitated diffusion of water through cell membranes. Some kidney cells are adapted to have lots of aquaporins. The aquaporins allow the cells to reabsorb a lot of the water that would otherwise be excreted by the body