Membrane Transport 1.4

Question 1

What are the 2 properties of membranes?

Answer 1

semi-permiable- only certain things can cross

selective- membranes can regulate material passage

Question 2

What are the two types of membrane transport?

Answer 2

passive

• along a concentration gradient
• no ATP required

active

• against a concentration gradient
• ATP required

Question 3

What are the 2 types of passive transport?

Answer 3

facilitated diffusion and simple diffusion

Question 4

What is facilitated diffusion?

Answer 4

• passive movement of molecules across a cell membrane via channel proteins
• involved large molecules (glucose, ions etc.)
  Example: voltage-gated channels control the flow of ions in neurons

Question 5

What is simple diffusion?

Answer 5

• the net movement of particles from a region of higher concentration to a region of lower concentration along the concentration gradient until an equillibrium is reached
• involves small molecules (oxygen, steroids, C02)

Question 6

What is active transport?

Answer 6

• active transport uses ATP energy to move molecules against a concentration gradient
• protein pumps in the membrane are used for active transport
• each pump only pumps specific substances so cells can control what is absorbed/expelled.
  pumps work in a specific direction
  example: sodium-potassium pumps moves ions in neuron

Question 7

ESSAY Q: Outline 4 types of membrane transport, including thier use of energy.

Answer 7

• simple diffusion is a passive movement of molecules along a concentration gradient
• facilitated diffusion is a passive movement of molecules along a concentration gradient through a protein channel without the use of energy
• active transport is the movement of molecules against the concentration gradient through membrane pumps with the use of ATP energy
• endocytosis is the formation of vesicles to release molecules from cell with use of energy