Membrane Transport

Question 1

Selective Permeability (Lipid Bilayer)

Answer 1

Non-Polar: Easily crossed as they are hydrophobic
Polar: Difficultly crossing as they are hydrophilic
Charged: Passing is prevent as they have a sphere of water around it and the tails are hydrophobic
Large: Don’t fit through pores

Question 2

Selective Permeability (Transport Proteins)

Answer 2

Channel: Hydrophilic channel that allows for polar and charged molecules to pass through
Carrier: Holds onto certain molecules and changes shape in a way that shuttles molecules across membrane

Question 3

Directional Movement

Answer 3

Molecules in substance are in constant random motion and disperse from areas of high concentration to low
- Molecules will disperse till they reach a state of equilibrium
- Factors that affect rate of diffusion: concentration gradient, temperature, distance, area of membrane, permeability of membrane

Question 4

Passive Transport

Answer 4

Diffusion of a substance across membrane with no energy investment; no energy investment as substance moves down concentration gradient

Question 5

Passive Transport (Osmosis)

Answer 5

Diffusion of water; Balances concentration gradient of solute by changing the volume of solute

Hypotonic- [Solute]Out<[Solute]In; H2O goes in=Swells

Isotonic- [Solute]Out= [Solute]In

Hypertonic- [Solute]Out> [Solute]In; H2O goes out=Shrivels

Question 6

Facilitated Diffusion

Answer 6

Diffusion with the help of transport proteins
-Provides hydrophilic (polar) passageways that allow small, polar ions and molecules to cross

Question 7

Active Transport

Answer 7

Uses energy to move solutes against concentration gradient
-Uses carrier proteins

Question 8

Bulk Transport

Answer 8

Transport of large molecules
-Molecules must be packaged in vesicles or vacuoles (rearrangement of plasma membrane is required to form vesicles)
-Endocytosis- Cell takes in material by forming vesicles
-Exocytosis- Cell exports material by fusing vesicles with plasma membrane