2.4 - Transport Across Membranes

Question 1

3 Types of Passive Membrane Transport

Answer 1

1 Simple Diffusion
2 Facilitated Diffusion
3 Osmosis

Question 2

Passive Membrane Transport Simple Diffusion

Answer 2

Small molecules (CO2, H2O, O2, salts) can move between the phospholipid molecules of the bilayer. Molecules move from a HIGH concentration ([High]) to a LOW concentration ([Low]) along a concentration gradient (Brownian motion) until a balance is achieved.

Question 3

Passive Membrane Transport Facilitated Diffusion

Answer 3

Some proteins in the cell membrane provide a tunnel for larger molecules (ex:glucose) to diffuse through. The molecules still go with the concentration gradient!

Question 4

Passive Membrane Transport Osmosis

Answer 4

Osmosis is the movement of water from an area of [Low] of solute to a [High] of solute through a selectively permeable membrane.

Question 5

3 Conditions of Osmosis (Passive Membrane Transport)

Answer 5

1 Hypertonic solution
2 Hypotonic solution
3 Isotonic solution

Question 6

Active Membrane Transport

Answer 6

Active transport requires ATP to “pump” nutrients across cell membranes. Using ATP, carrier proteins “pump” substances through the membrane from an area of low to an area of high, against the gradient

Question 7

Exocytosis

Answer 7

Exocytosis is moving materials out of the cell. It is the reverse of endocytosis. Vesicles (from the Golgi) fuses with the membrane and release its contents out of the cell

Question 8

Exocytosis

Answer 8

Exocytosis is moving materials out of the cell. It is the reverse of endocytosis. Vesicles (from the Golgi) fuses with the membrane and release its contents out of the cell

Question 9

ATP

Answer 9

Adenosine triphosphate is the primary carrier of energy in cells. The water-mediated reaction known as hydrolysis releases energy from the chemical bonds in ATP to fuel cellular processes

Question 10

2 Types of Active Membrane Transport

Answer 10

1 Primary Active Transport

2 Secondary Active Transport

Question 11

Primary Active Transport

Answer 11

The Sodium-potassium pump moves Na+ using the energy of ATP hydrolysis to establish a concentration gradient of Na+

Question 12

Secondary Active Protein

Answer 12

Na+ moving with the concentration gradient established by the sodium-potassium pump dives the transport of glucose against its concentration gradient.

Question 13

Hypertonic solution

Answer 13

fluid surrounding the cell has a higher solute [ ] than inside. Water diffuses out and the cell shrinks. ([ ] is concentration)

Question 14

Hypotonic solution

Answer 14

[ ] of solute is higher inside the cell than outside. Water will diffuse into the cell, and the cell expands (and can burst!) ([ ] is concentration)

Question 15

Isotonic solution

Answer 15

solute [ ] outside of cell is equal to [ ] inside cell. Cell remains normal ([ ] is concentration)