Membranes

Question 1

What happens when membrane proteins are inserted?

Answer 1

• introduces asymmetry, because integral membrane proteins can move laterally (not vertically)

Question 2

What is the effect of freeze fracture?

Answer 2

• Freeze fracture splits membranes into two leaflets, freezing tightly binds phospholipids to surrounding water molecules by hydrogen bonds (in frozen state - only held together by van der wall forces)

Question 3

Diffusion

Answer 3

• passive mixing of substances resulting in net transport along concentration gradient
• random walk of individual molecules because of thermal motions and collisions (distance is proportional to root t)
• happens if there is concentration gradient, until equilibriumis reached

Question 4

Osmosis

Answer 4

• the diffusion of water

Question 5

Hypertonic

Answer 5

• a hypertonic solution is one in which there is a greater concentration or number of solute particles outside a membrane than there are inside it.
• Ocean cannot quench your thirst, water flow out of your cells to dilute

Question 6

Hypotonic

Answer 6

• tap water, net water flows in cells

- Less concentrated than the cell

Question 7

Passive vs active transport

Answer 7

• Passive: facilitate diffusion
  1) Gated channel proteins: can be saturated, they must bind to substrate
  2) Carrier proteins: always gates, open upon changes in electricity or binding regulators (saturation occurs much earlier than gated)
• Active: transport molecules against their concentration gradient

Question 8

How does glucose carrier work?

Answer 8

• binding of sugar to either side causes a conformation change in carrier protein, transports sugar to the other side