Transport across membranes

Question 1

Components of Fluid Mosaic model?

Answer 1

• Carbs
• Peripheral membrane proteins
• Cholesterol molecules
• Integral proteins
• Membrane proteins

Question 2

What do carbs do?

Answer 2

Attached to outer surface of proteins (forming glycoproteins) or lipids (forming glycolipids)

Question 3

Peripheral membrane proteins?

Answer 3

Do not penetrate bilayer at all

Question 4

Cholesterol?

Answer 4

Interspersed among phospholipids tails in the bilayer influence the fluidity of fatty acids in the membrane

Question 5

Membranes are:

Answer 5

• Fluid, not rigid
• Readily deformed and self-sealing
• Selectively permeable
• Composed of lipids, proteins with some carbs
• Asymmetric
• Lipid-Protein ratio varies

Question 6

Membrane Lipids?

Answer 6

• Phospholipids comprise bulk of membrane lipids
• Phospholipids are asymmetrically distributed between inner and outer membranes
• Phospholipids spontaneously form bilayers

Question 7

Phospholipids?

Answer 7

• Hydrophobic hydrocarbon tail

- Hydrophilic phosphate head

Question 8

Transport mechanisms:

Answer 8

1. Passive transport
2. Facilitated transport
3. Active Transport

Question 9

Passive transport?

Answer 9

Diffusion through the membrane down a concentration/electrical potential gradient

Question 10

Facilitated transport?

Answer 10

Diffusion through a transport channel, down a concentration/electrical potential gradient

Question 11

Active Transport?

Answer 11

Through a transport channel and against a concentration gradient

Question 12

Where does Na+ go?

Answer 12

Outside the cell

Question 13

Where does K+ go?

Answer 13

Inside the cell