Cellular Transport

Cellular Transport

I. General A. Definition = molecules moving

across the cell membraneB. Cell Membrane

is selectively permeable(lets some things in,

some things out, but not everything)

Cell Membrane

C. Two Main Types of Transport

1. Passive Transport

2. Active Transport

1. Passive Transport

a. Requires no energy

b. Caused by random movement of molecules

c. Molecules move with the concentration gradient

Concentration Gradient

= difference in the concentration of a substance across a space

c. Examples of Passive Transport

i. Diffusion = process by which

molecules movefrom areas of high concentration

to areas of low concentration

until equilibrium is reached

Diffusion

Equilibrium =

balance of molecules on both sides of membrane

?s 1-5

c. Examples of Passive Transport

ii. Osmosis = diffusion of water

iii. Ion Channels = charged molecules moved across membrane by proteins

c. Examples of Passive Transport

iv. Facilitated Diffusion molecules moved across

membrane by carrier proteins

?s 6-10

2. Active Transport

a. Requires Energy (ATP)

b. Molecules move from areas of low concentration to areas of high concentration

c. Molecules move against the concentration gradient

c. Examples ofActive Transport

i. Carrier Protein Pumps

ii. Movement of molecules by vesicles

i. Carrier Protein Pumps

• E.g. Sodium/Potassium Pump- Ion exchange- Na+ moved out / K+ moved in- K+ moved out / Na+ moved in

ii. Movement by vesicles

• Vesicles form • Move molecules across the

membrane

ii. Movement by vesicles

• Endocytosis - into a cell

ii. Movement by vesicles

• Exocytosis – out of a cell

Passive vs. Active Transport

?s 11-14