lecture 8

Question 1

active transport carrier mediated transport

Answer 1

• Active transport:
  Think of a car on a hill! Moving downhill vs uphill
• Also requires a carrier protein
• Expends energy
• Transfer its passenger “uphill” against
  a concentration gradient

Question 2

primary active transport

Answer 2

• Energy (ATP) is directly required to move a substance
  against its concentration gradient
• Carrier’s binding sites have a greater affinity for the passenger
  ion on the low-concentration side where the ion is picked up
  and a lower affinity on the high-concentration side where the
  ion is dropped off

Question 3

primary active transport example

Answer 3

These carriers are often called pumps (Act as enzymes with
ATPase activity)
* Two types that always transport ions:
* single type of passenger (i.e., H+ pump or Ca2+ pump)
* Na+ – K+ pump involves the transfer of two different
substances either simultaneously in the same direction or
sequentially in opposite directions

Question 4

secondary active transport

Answer 4

Energy is required in the entire
process but is NOT directly
required to run the pump (NO
ATP is used directly by pump)
* Uses “secondhand” energy stored
in the form of an ion (e.g. Na+)
concentration gradient to move the
cotransported molecule uphill