Membranes And Transport

Question 1

What are the 3 characteristics of channel proteins?

Answer 1

• Form an aqueous pore that spans the whole membrane
• High transport capacity
• Selective

Question 1

What are the two main types of membrane transporters?

Answer 1

1. Channel proteins
2. Carrier proteins

Question 2

What are the characteristics of carrier proteins?

Answer 2

• Binding of specific substances triggers conformational change
• Low transport capacity
• Selective with stereoselectivity

Question 3

What are the three types of transportation across cell membranes?

Answer 3

• Simple diffusion
• Facilitated diffusion
• Active transport

Question 4

What determines the direction of ion movement across a membrane?

Answer 4

Electrochemical and concentration gradients determine the direction of movement.

Question 5

What are the three types of carrier proteins based on substrate transport direction?

Answer 5

• Uniport: transports 1 substrate
• Symport: transports 2+ substrates in the same direction
• Antiport: transports substrates in different directions

Question 6

What are the three main types of gated ion channels?

Answer 6

• Mechanically gated channels
• Voltage gated channels
• Ligand gated channels

Question 7

What are the main mechanisms for regulating intracellular pH?

Answer 7

• Na/H+ exchange
• Na+-HCO3 co-transport
• Cl-/HCO3 exchange

Question 8

How is intracellular Ca2+ concentration maintained?

Answer 8

• Ca2+ ATPase moves Ca2+ out of cell or into intracellular stores (ER and mitochondria)
• Na+/Ca2+ exchanger moves Na+ into cell in exchange for moving Ca2+ out of cell
• Stored Ca2+ can be released from signals from the plasma membrane

Question 8

What is osmolarity and how does it affect cells?

Answer 8

Osmolarity is the number of particles in solution. Increased intracellular osmolarity leads to cell swelling, while decreased intracellular osmolarity leads to cell shrinking.

Question 9

What is the resting membrane potential?

Answer 9

The resting membrane potential is reached when the electrical gradient is equal and opposite to the concentration gradient. The intracellular environment is more negative compared to the extracellular environment.

Question 10

Does K+ move in or out of the cell?

Answer 10

Outside

Question 11

What are the two types of ion channels?

Answer 11

Open channels
gated channels

Question 12

Na/K-ATPase moves 2 K ions (in/out) the cell

Answer 12

In

Question 13

Na/K-ATPase moves 3 Na (in/out) the cell

Answer 13

Out