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Chapter 5 Plasma Membranes > Diffusion > Flashcards

Flashcards in Diffusion Deck (17):
1

What is diffusion?

-Movement of particles from a region of high to a region of low concentration.
-Passive process, doesn't require energy and will continue until an equilibrium.

2

What does equilibrium mean?

-Balance in concentration.

3

Why does diffusion happen?

-Due to particles in a gas or liquid having kinetic energy.
-Movement is random and will carry on until an equilibrium.

4

When is diffusion fastest and why?

-Over short distances because more frequent and successful collisions as they have most kinetic energy.

5

What factors affect the diffusion rate?

-Temperature.
-Concentration difference.
-Distance.

6

How does temperature affect diffusion rate?

-The higher the temperature, the higher the rate due to more kinetic energy and higher speeds.

7

How does concentration difference affect diffusion rate?

-The greater the difference in concentration the faster the rate of diffusion.

8

How does distance affect diffusion rate?

-The shorter the distance the faster the rate of diffusion.

9

What is simple diffusion?

-Diffusion in the absence of a barrier or membrane.

10

How does diffusion happen across a membrane?

-Particles pass through the phospholipid bilayer.
-Can only happen if membrane is permeable to particles for example oxygen can diffuse freely.

11

Why are membranes partially permeable?

-Only allows certain molecules diffuse through.
-Ions cannot pass easily because hydrophobic interior repels these.
-Polar molecules can diffuse at a slow rate.
-Small polar molecules ca diffuse much easier.

12

How does surface area affect rate of diffusion across a membrane?

-The larger the area of exchange surface, the higher the rate of diffusion.

13

How does thickness of membrane affect the rate of diffusion across a membrane?

-The thinner the exchange surface, the higher the rate of diffusion.

14

What is facilitated diffusion?

-Diffusion across a membrane through channel proteins.
-Passive process, down a concentration gradient and doesn't requires energy.

15

What particles can facilitated diffusion allow to pass?

-Polar molecules and ions.

16

Are membranes with protein channels permeable?

-Selectively permeable.

17

What factors affect the rate of facilitated diffusion?

-Temperature.
-Membrane thickness.
-Number of channel proteins.