Chapter 4: Section 4.3c: Active Transport

Question 1

Two categories of active processes

Answer 1

Primary active transport

Secondary active transport

Question 2

Define primary active transport

Answer 2

• Uses energy directly from ATP
• Phosphate group from ATP is added to a transport protein
• The addition of Pi changes transport protein shape
• The change in shape results in movement of the solute across membrane against (up) concentration gradient

Question 3

Mechanisms of primary active transport

Answer 3

Ion pumps

Sodium-potassium exchange pump

Question 4

Define ion pumps

Answer 4

• Active transport proteins that move ions across the cell membrane.
• Helps cell maintain the internal concentration of ions

Question 5

Define sodium-potassium exchange pumps

Answer 5

• Moves one ion into the cell against its gradient while moving another ion out of the cell against its gradient
• Pumps three Na+ out for every two K+ pumped into the cell
• Maintains a steep concentration gradient for these ions
• Maintains an electrochemical gradient because of unequal distribution of positive and negative substances across membrane - membrane potential

Question 6

Define secondary transport

Answer 6

Moves one substance against its concentration gradient by using energy provided by the movement of second substance down its gradient through a channel

Dependent on Na+/K+ pumps for energy

Question 7

Two types of secondary active transport

Answer 7

Symport and antiport secondary active transport

Question 8

Define symport secondary active transport

Answer 8

Two substances are moved in the same direction across the plasma membrane. Substances transported into the cell while sodium goes into the cell.

Question 9

Define antiport secondary active transport

Answer 9

Two substances are moved in opposite directions across the plasma membrane. Substances transported out of the cell while sodium goes into the cell.

Question 10

Define vesicular transport

Answer 10

Requires energy to transport vesicles

Question 11

Two types of of vesicular transport

Answer 11

Exocytosis and endocytosis

Question 12

Define excytosis

Answer 12

Involves the fusion of a vesicle with the cell membrane and then the release of those materials out of the cell.

Question 13

Define endocytosis

Answer 13

Involves the fusion of a vesicle with the cell membrane and then the release of those materials into the cell.

Question 14

Three types of endocytosis

Answer 14

Phagocytosis, pinocytosis, and receptor-mediated endocytosis.

Question 15

Define phagocytosis

Answer 15

Nonspecific (occurs same way every time) process and occurs when cell engulfs large particles external to cell.

Involves the formations of large extensions called pseudopodia which enclose the particle in a sac.

Cell eating

Question 16

Define pinocytosis

Answer 16

Occurs when the cell internalizes droplets of interstitial fluid (ECF).

Involves formation of many small vesicles

Is nonspecific because of all dissolved solutes within the droplets are taken into the cell.

Question 17

Define receptor-mediated endocytosis

Answer 17

The movement of specific molecules from the interstitial environment into a cell but these specific molecules must first bind to a receptor.

Enables the cell to obtain bulk qualities of substances.