Movement of molecules across cell membranes

Question 1

What type of forces are used with the movement of fluid and solutes from interstitial fluid into the cell?

Answer 1

1. diffusion
2. facilitated diffusion
3. active transport
4. co-transport

Question 2

What are the two main forms of transport ?

Answer 2

Hydrophilic channels

ATP-pump

Question 3

What is simple diffusion?

Answer 3

-Down a concentration or electrical gradient

= through membrane, pores, protein channels

Question 4

What is facilitated diffusion?

Answer 4

Down a concentration or electrical gradient

• Carrier mediated - need integral membrane proteins
• transporter is specific for the molecule
• rate limited by binding and conformational change in carrier protein

Question 5

What is active transport?

Answer 5

• Up a concentration or electrical gradient

* carrier mediated and energy dependent

Question 6

What about Membrane Channels?

Answer 6

• The protein transmembrane channels that permit simple diffusion
  = rate of movement is limited by rate of diffusion (proportional to a concentration gradient)
• Gated ion channels

Question 7

What are the 3 different type of gated ion channels?

Answer 7

1. voltage-gated (specific channel for each) i.e. Na+ or K+
2. Chemical or ligand-gated
   i. e. acetylcholine
3. Mechanically
   i. e. sound waves in inner ear open ion channels

Question 8

what two things affect ion movement via transport proteins?

Answer 8

1. concentration gradient

2. electrical gradient